An air filter being cleaned

Indoor air quality (IAQ) is the air quality within buildings and structures. Poor indoor air quality due to indoor air pollution is known to affect the health, comfort, and well-being of building occupants. It has also been linked to sick building syndrome, respiratory issues, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include: secondhand tobacco smoke, air pollutants from indoor combustion, radon, molds and other allergens, carbon monoxide, volatile organic compounds, legionella and other bacteria, asbestos fibers, carbon dioxide,[1] ozone and particulates. Source control, filtration, and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality.

IAQ is evaluated through collection of air samples, monitoring human exposure to pollutants, analysis of building surfaces, and computer modeling of air flow inside buildings. IAQ is part of indoor environmental quality (IEQ), along with other factors that exert an influence on physical and psychological aspects of life indoors (e.g., lighting, visual quality, acoustics, and thermal comfort).[2]

Indoor air pollution is a major health hazard in developing countries and is commonly referred to as "household air pollution" in that context.[3] It is mostly relating to cooking and heating methods by burning biomass fuel, in the form of wood, charcoal, dung, and crop residue, in indoor environments that lack proper ventilation. Millions of people, primarily women and children, face serious health risks. In total, about three billion people in developing countries are affected by this problem. The World Health Organization (WHO) estimates that cooking-related indoor air pollution causes 3.8 million annual deaths.[4] The Global Burden of Disease study estimated the number of deaths in 2017 at 1.6 million.[5]


For health reasons it is crucial to breathe clean air, free from chemicals and toxicants as much as possible. It is estimated that humans spend approximately 90% of their lifetime indoors[6] and that indoor air pollution in some places can be much worse than that of the ambient air.[7][8]

Various factors contribute to high concentrations of pollutants indoors, ranging from influx of pollutants from external sources, off-gassing by furniture, furnishings including carpets, indoor activities (cooking, cleaning, painting, smoking, etc. in homes to using office equipment in offices), thermal comfort parameters such as temperature, humidity, airflow and physio-chemical properties of the indoor air.[citation needed] Air pollutants can enter a building in many ways, including through open doors or windows. Poorly maintained air conditioners/ventilation systems can harbor mold, bacteria, and other contaminants, which are then circulated throughout indoor spaces, contributing to respiratory problems and allergies.

There have been many debates among indoor air quality specialists about the proper definition of indoor air quality and specifically what constitutes "acceptable" indoor air quality.

Health effects

Share of deaths from indoor air pollution. Darker colors mean higher numbers.

IAQ is significant for human health as humans spend a large proportion of their time in indoor environments. Americans and Europeans on average spend approximately 90% of their time indoors.[9][10]

The World Health Organization (WHO) estimates that 3.2 million people die prematurely every year from illnesses attributed to indoor air pollution caused by indoor cooking, with over 237 thousand of these being children under 5. These include around an eighth of all global ischaemic heart disease, stroke, and lung cancer deaths. Overall the WHO estimated that poor indoor air quality resulted in the loss of 86 million healthy life years in 2019.[11]

Studies in the UK and Europe show exposure to indoor air pollutants, chemicals and biological contamination can irritate the upper airway system, trigger or exacerbate asthma and other respiratory or cardiovascular conditions, and may even have carcinogenic effects.[12][13][14][15][16][17]

Poor indoor air quality can cause sick building syndrome. Symptoms include burning of the eyes, scratchy throat, blocked nose, and headaches.[18]

Common pollutants

Generated by indoor combustion

Main article: Household air pollution

Further information: Energy poverty and cooking

a 3-stone stove
A traditional wood-fired 3-stone stove in Guatemala, which causes indoor air pollution

Indoor combustion, such as for cooking or heating, is a major cause of indoor air pollution and causes significant health harms and premature deaths. Hydrocarbon fires cause air pollution. Pollution is caused by both biomass and fossil fuels of various types, but some forms of fuels are more harmful than others.

Indoor fire can produce black carbon particles, nitrogen oxides, sulfur oxides, and mercury compounds, among other emissions.[19] Around 3 billion people cook over open fires or on rudimentary cook stoves. Cooking fuels are coal, wood, animal dung, and crop residues.[20] IAQ is a particular concern in low and middle-income countries where such practices are common.[21]

Cooking using natural gas (also called fossil gas, methane gas or simply gas) is associated with poorer indoor air quality. Combustion of gas produces nitrogen dioxide and carbon monixide, and can lead to increased concentrations of nitrogen dioxide throughout the home environment.[22][23]

Carbon monoxide

Main article: Carbon monoxide poisoning

One of the most acutely toxic indoor air contaminants is carbon monoxide (CO), a colourless and odourless gas that is a by-product of incomplete combustion. Carbon monoxide may be emitted from tobacco smoke and generated from malfunctioning fuel burning stoves (wood, kerosene, natural gas, propane) and fuel burning heating systems (wood, oil, natural gas) and from blocked flues connected to these appliances.[24] In developed countries the main sources of indoor CO emission come from cooking and heating devices that burn fossil fuels and are faulty, incorrectly installed or poorly maintained.[25] Appliance malfunction may be due to faulty installation or lack of maintenance and proper use.[24] In low- and middle-income countries the most common sources of CO in homes are burning biomass fuels and cigarette smoke.[25]

Health effects of CO poisoning may be acute or chronic and can occur unintentionally or intentionally (self-harm). By depriving the brain of oxygen, acute exposure to carbon monoxide may have effects on the neurological system (headache, nausea, dizziness, alteration in consciousness and subjective weakness), the cardiovascular and respiratory systems (myocardial infarction, shortness of breath, or rapid breathing, respiratory failure). Acute exposure can also lead to long-term neurological effects such as cognitive and behavioural changes. Severe CO poisoning may lead to unconsciousness, coma and death. Chronic exposure to low concentrations of carbon monoxide may lead to lethargy, headaches, nausea, flu-like symptoms and neuropsychological and cardiovascular issues.[26][24]

The WHO recommended levels of indoor CO exposure in 24 hours is 4 mg/m3.[27] Acute exposure should not exceed 10 mg/m3 in 8 hours, 35 mg/m3 in one hour and 100 mg/m3 in 15 minutes.[25]

Secondhand tobacco smoke

Main article: Passive smoking

Secondhand smoke is tobacco smoke which affects people other than the 'active' smoker. It is made up of the exhaled smoke (15%) and mostly of smoke coming from the burning end of the cigarette, known as sidestream smoke (85%).[28]

Secondhand smoke contains more than 7000 chemicals, of which hundreds are harmful to health.[28] Secondhand tobacco smoke includes both a gaseous and a particulate materials which, with particular hazards arising from levels of carbon monoxide and very small particulates (fine particulate matter, especially PM2.5 and PM10) which get into the bronchioles and alveoles in the lung.[29] Inhaling secondhand smoke on multiple occasions can cause asthma, pneumonia, lung cancer, and sudden infant death syndrome, among other conditions.[30]

Thirdhand smoke (THS) refers to chemicals that settle on objects and bodies indoors after smoking. Exposure to thirdhand smoke can happen even after the actual cigarette smoke is not present anymore and affect those entering the indoor environment much later. Toxic substances of THS can react with other chemicals in the air and produce new toxic chemicals that are otherwise not present in cigarettes.[31]

The only certain method to improve indoor air quality as regards secondhand smoke is to eliminate smoking indoors.[32] Indoor e-cigarette use also increases home particulate matter concentrations.[33]


Atmospheric particulate matter, also known as particulates, can be found indoors and can affect the health of occupants. Indoor particulate matter can come from different indoor sources or be created as secondary aerosols through indoor gas-to-particle reactions. They can also be outdoor particles that enter indoors. These indoor particles vary widely in size, ranging from nanomet (nanoparticles/ultrafine particles emitted from combustion sources) to micromet (resuspensed dust).[34]

Particulate matter can also be produced through cooking activities. Frying produces higher concentrations than boiling or grilling and cooking meat produces higher concentrations than cooking vegetables.[35] Preparing a Thanksgiving dinner can produce very high concentrations of particulate matter, exceeding 300 µg/m3.[36]

Generated from building materials, furnishing and consumer products

Volatile organic compounds

A "sick" building emitting fine particulates[37]

Volatile organic compounds (VOCs) include a variety of chemicals, some of which may have short- and long-term adverse health effects. There are numerous sources of VOCs indoors, which means that their concentrations are consistently higher indoors (up to ten times higher) than outdoors.[38] Some VOCs are emitted directly indoors, and some are formed through the subsequent chemical reactions that can occur in the gas-phase, or on surfaces.[39][40] VOCs presenting health hazards include benzene, formaldehyde, tetrachloroethylene and trichloroethylene.[41]

VOCs are emitted by thousands of indoor products. Examples include: paints, varnishes, waxes and lacquers, paint strippers, cleaning and personal care products, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.[42] Chlorinated drinking water releases chloroform when hot water is used in the home. Benzene is emitted from fuel stored in attached garages.

Human activities such as cooking and cleaning can also emit VOCs.[43][44] Cooking can release long-chain aldehydes and alkanes when oil is heated and terpnes can be released when spices are prepared and/or cooked.[43] Leaks of natural gas from cooking appliances have been linked to elevated levels of VOCs including benzene in homes in the USA.[45] Cleaning products contain a range of VOCs, including monoterpenes, sesquiterpenes, alcohols and esters. Once released into the air, VOCs can undergo reactions with ozone and hydroxyl radicals to produce other VOCs, such as formaldehyde.[44]

Testing emissions from building materials used indoors has become increasingly common for floor coverings, paints, and many other important indoor building materials and finishes.[46] Indoor materials such as gypsum boards or carpet act as VOC 'sinks', by trapping VOC vapors for extended periods of time, and releasing them by outgassing. The VOCs can also undergo transformation at the surface through interaction with ozone.[40] In both cases, these delayed emissions can result in chronic and low-level exposures to VOCs.[47]

Several initiatives aim to reduce indoor air contamination by limiting VOC emissions from products. There are regulations in France and in Germany, and numerous voluntary ecolabels and rating systems containing low VOC emissions criteria such as EMICODE,[48] M1,[49] Blue Angel[50] and Indoor Air Comfort[51] in Europe, as well as California Standard CDPH Section 01350[52] and several others in the US. Due to these initiatives an increasing number of low-emitting products became available to purchase.

At least 18 microbial VOCs (MVOCs) have been characterised[53][54] including 1-octen-3-ol (mushroom alcohol), 3-Methylfuran, 2-pentanol, 2-hexanone, 2-heptanone, 3-octanone, 3-octanol, 2-octen-1-ol, 1-octene, 2-pentanone, 2-nonanone, borneol, geosmin, 1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, and thujopsene. The last four are products of Stachybotrys chartarum, which has been linked with sick building syndrome.[53]

Asbestos fibers

Many common building materials used before 1975 contain asbestos, such as some floor tiles, ceiling tiles, shingles, fireproofing, heating systems, pipe wrap, taping muds, mastics, and other insulation materials. Normally, significant releases of asbestos fiber do not occur unless the building materials are disturbed, such as by cutting, sanding, drilling, or building remodelling. Removal of asbestos-containing materials is not always optimal because the fibers can be spread into the air during the removal process. A management program for intact asbestos-containing materials is often recommended instead.

When asbestos-containing material is damaged or disintegrates, microscopic fibers are dispersed into the air. Inhalation of asbestos fibers over long exposure times is associated with increased incidence of lung cancer, mesothelioma, and asbestosis. The risk of lung cancer from inhaling asbestos fibers is significantly greater for smokers. The symptoms of disease do not usually appear until about 20 to 30 years after the first exposure to asbestos.

Although all asbestos is hazardous, products that are friable, e.g. sprayed coatings and insulation, pose a significantly higher hazard as they are more likely to release fibers to the air.[55]


See also: Ground-level ozone

Indoors ozone (O3) is produced by certain high-voltage electric devices (such as air ionizers), and as a by-product of other types of pollution. It appears in lower concentrations indoors than outdoors, usually at 0.2-0.7 of the outdoor concentration.[56] Typically, most ozone is lost to surface reactions indoors, rather than to reactions in air, due to the large surface to volume ratios found indoors.[57]

Outdoor air used for ventilation may have sufficient ozone to react with common indoor pollutants as well as skin oils and other common indoor air chemicals or surfaces. Particular concern is warranted when using "green" cleaning products based on citrus or terpene extracts, because these chemicals react very quickly with ozone to form toxic and irritating chemicals[44] as well as fine and ultrafine particles.[58] Ventilation with outdoor air containing elevated ozone concentrations may complicate remediation attempts.[59]

The WHO standard for ozone concentration is 60 μg/m3 for long-term exposure and 100 μg/m3 as the maximum average over an 8-hour period.[27] The EPA standard for ozone concentration is 0.07 ppm average over an 8-hour period.[60]

Biological agents

Mold and other allergens

Main articles: Indoor mold and Mold health issues

Occupants in buildings can be exposed to fungal spores, cell fragments, or mycotoxins which can arise from a host of means, but there are two common classes: (a) excess moisture induced growth of mold colonies and (b) natural substances released into the air such as animal dander and plant pollen.[61]

While mold growth is associated with high moisture levels,[62] it is likely to grow when a combination of favorable conditions arises. As well as high moisture levels, these conditions include suitable temperatures, pH and nutrient sources.[63] Mold is primarily a surface phenomenon, and it reproduces by releasing spores, which can travel and settle in different locations. When these spores experience appropriate conditions, they can germinate and lead to mycelium growth.[64] Different mold species favor different environmental conditions to germinate and grow, some being more hydrophilic (growing at higher levels of relative humidity) and other more xerophilic (growing at levels of relative humidity as low as 75 - 80%).[64][65]

Mold growth can be inhibited by keeping surfaces at conditions that are further from condensation, with relative humidity levels below 75%. This usually translates to a relative humidity of indoor air below 60%, in agreement with the guidelines for thermal comfort that recommend a relative humidity between 40 - 60 %. Moisture buildup in buildings may arise from water penetrating areas of the building envelope or fabric, from plumbing leaks, rainwater or groundwater penetration, or from condensation due to improper ventilation, insufficient heating or poor thermal quality of the building envelope.[66] Even something as simple as drying clothes indoors on radiators can increase the risk of mold growth, if the humidity produced is not able to escape the building via ventilation.[67]

In many cases, if materials have failed to dry out several days after the suspected water event, mold growth can be suspected even if it is not immediately visible. Through a mold investigation, which may include destructive inspection, one should be able to determine the presence or absence of mold. In a situation where there is visible mold and the indoor air quality may have been compromised, mold remediation may be needed.

Mold predominantly affects the airways and lungs. Known effects of mold on health include asthma development and exacerbation,[68] with children and elderly at greater risk of more severe health impacts.[69] Infants in homes with mold have a much greater risk of developing asthma and allergic rhinitis.[61] More than half of adult workers in moldy or humid buildings suffer from nasal or sinus symptoms due to mold exposure.[61] Some varieties of mold contain toxic compounds (mycotoxins). However, exposure to hazardous levels of mycotoxin via inhalation is not possible in most cases, as toxins are produced by the fungal body and are not at significant levels in the released spores


Legionnaires' disease is caused by a waterborne bacterium Legionella that grows best in slow-moving or still, warm water. The primary route of exposure is through the creation of an aerosol effect, most commonly from evaporative cooling towers or showerheads. A common source of Legionella in commercial buildings is from poorly placed or maintained evaporative cooling towers, which often release water in an aerosol which may enter nearby ventilation intakes. Outbreaks in medical facilities and nursing homes, where patients are immuno-suppressed and immuno-weak, are the most commonly reported cases of Legionellosis. More than one case has involved outdoor fountains at public attractions. The presence of Legionella in commercial building water supplies is highly under-reported, as healthy people require heavy exposure to acquire infection.

Legionella testing typically involves collecting water samples and surface swabs from evaporative cooling basins, shower heads, faucets/taps, and other locations where warm water collects. The samples are then cultured and colony forming units (cfu) of Legionella are quantified as cfu/liter.

Legionella is a parasite of protozoans such as amoeba, and thus requires conditions suitable for both organisms. The bacterium forms a biofilm which is resistant to chemical and antimicrobial treatments, including chlorine. Remediation for Legionella outbreaks in commercial buildings vary, but often include very hot water flushes (160 °F; 70 °C), sterilisation of standing water in evaporative cooling basins, replacement of shower heads, and in some cases flushes of heavy metal salts. Preventive measures include adjusting normal hot water levels to allow for 120 °F (50 °C) at the tap, evaluating facility design layout, removing faucet aerators, and periodic testing in suspect areas.

Other bacteria

Airborne bacteria

There are many bacteria of health significance found in indoor air and on indoor surfaces. The role of microbes in the indoor environment is increasingly studied using modern gene-based analysis of environmental samples. Currently efforts are under way to link microbial ecologists and indoor air scientists to forge new methods for analysis and to better interpret the results.[70]

A large fraction of the bacteria found in indoor air and dust are shed from humans. Among the most important bacteria known to occur in indoor air are Mycobacterium tuberculosis, Staphylococcus aureus, Streptococcus pneumoniae.

Carbon dioxide

Humans are the main indoor source of carbon dioxide (CO2) in most buildings. Indoor CO2 levels are an indicator of the adequacy of outdoor air ventilation relative to indoor occupant density and metabolic activity.

Indoor CO2 levels above 500 ppm can lead to higher blood pressure and heart rate, and increased peripheral blood circulation.[71] With CO2 concentrations above 1000 ppm cognitive performance might be affected, especially when doing complex tasks, making decision making and problem solving slower but not less accurate.[72][73] However, evidence on the health effects of CO2 at lower concentrations is conflicting and it is difficult to link CO2 to health impacts at exposures below 5000 ppm - reported health outcomes may be due to the presence of human bioeffluents, and other indoor air pollutants related to inadequate ventilation.[74]

Indoor carbon dioxide concentrations can be used to evaluate the quality of a room or a building's ventilation.[75] To eliminate most complaints caused by CO2, the total indoor CO2 level should be reduced to a difference of no greater than 700 ppm above outdoor levels.[76] The National Institute for Occupational Safety and Health (NIOSH) considers that indoor air concentrations of carbon dioxide that exceed 1000 ppm are a marker suggesting inadequate ventilation.[77] The UK standards for schools say that carbon dioxide levels of 800 ppm or lower indicate that the room is well-ventilated.[78] Regulations and standards from around the world show that CO2 levels below 1000 ppm represent good IAQ, between 1000 and 1500 ppm represent moderate IAQ and greater than 1500 ppm represent poor IAQ.[74]

Carbon dioxide concentrations in closed or confined rooms can increase to 1,000 ppm within 45 minutes of enclosure. For example, in a 3.5-by-4-metre (11 ft × 13 ft) sized office, atmospheric carbon dioxide increased from 500 ppm to over 1,000 ppm within 45 minutes of ventilation cessation and closure of windows and doors.[79]


Main article: Radon

Radon is an invisible, radioactive atomic gas that results from the radioactive decay of radium, which may be found in rock formations beneath buildings or in certain building materials themselves.

Radon is probably the most pervasive serious hazard for indoor air in the United States and Europe. It is a major cause of lung cancer, responsible for 3–14% of cases in countries, leading to tens of thousands of deaths.[80]

Radon gas enters buildings as a soil gas. As it is a heavy gas it will tend to accumulate at the lowest level. Radon may also be introduced into a building through drinking water particularly from bathroom showers. Building materials can be a rare source of radon, but little testing is carried out for stone, rock or tile products brought into building sites; radon accumulation is greatest for well insulated homes.[81] There are simple do-it-yourself kits for radon gas testing, but a licensed professional can also check homes.

The half-life for radon is 3.8 days, indicating that once the source is removed, the hazard will be greatly reduced within a few weeks. Radon mitigation methods include sealing concrete slab floors, basement foundations, water drainage systems, or by increasing ventilation.[82] They are usually cost effective and can greatly reduce or even eliminate the contamination and the associated health risks.[citation needed]

Radon is measured in picocuries per liter of air (pCi/L) or becquerel per cubic meter (Bq m-3). Both are measurements of radioactivity. The World Health Organization (WHO) sets the ideal indoor radon levels at 100 Bq/m-3.[83] In the United States, it is recommend to fix homes with radon levels at or above 4 pCi/L. At the same time it is also recommends that people think about fixing their homes for radon levels between 2 pCi/L and 4 pCi/L.[84] In the United Kingdom the ideal is presence of radon indoors is 100 Bq/m-3. Action needs to be taken in homes with 200 Bq/m-3 or more.[85]

Interactive maps of radon affected areas are available for various regions and countries of the world.[86][87][88]

IAQ and climate change

See also: Effects of climate change on human health

Indoor air quality is linked inextricably to outdoor air quality. The Intergovernmental Panel on Climate Change (IPCC) has varying scenarios that predict how the climate will change in the future.[89] Climate change can affect indoor air quality by increasing the level of outdoor air pollutants such as ozone and particulate matter.[90] Numerous predictions for how indoor air pollutants will change have been made,[91][92][93][94] and models have attempted to predict how the forecasted IPCC scenarios will vary indoor air quality and indoor comfort parameters such as humidity and temperature.[95]

The net-zero challenge requires significant changes in the performance of both new and retrofitted buildings. Studies agree that our increased energy efficient housing will trap pollutants inside them, whether produced indoors or outdoors, and lead to an increase in human exposure.[96][97]

Indoor air quality standards and monitoring

Quality guidelines and standards

For occupational exposure, there are standards, which cover a wide range of chemicals, and applied to healthy adults who are exposed over time at workplaces (usually industrial environments).These are published by organisations such as Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety and Health (NIOSH), the UK Health and Safety Executive (HSE).

There is no consensus globally about indoor air quality standards, or health-based guidelines. However, there are regulations from some individual countries and from health organisations. For example, the World Health Organization (WHO) has published health-based global air quality guidelines for the general population that are applicable both to outdoor and indoor air,[27] as well as the WHO IAQ guidelines for selected compounds,[98] whereas the UK Health Security Agency published IAQ guidelines for selected VOCs.[99] The Scientific and Technical Committee (STC34) of the International Society of Indoor Air Quality and Climate (ISIAQ) created an open database that collects indoor environmental quality guidelines worldwide.[100] The database is focused on indoor air quality (IAQ), but is currently extended to include standards, regulations, and guidelines related to ventilation, comfort, acoustics, and lighting.[101][102]

Real-time monitoring

Since indoor air pollutants can adversely affect human health, it is important to have real-time indoor air quality assessment/monitoring system that can help not only in the improvement of indoor air quality but also help in detection of leaks, spills in a work environment and boost energy efficiency of buildings by providing real-time feedback to the heating, ventilation, and air conditioning (HVAC) system(s).[103] Additionally, there have been enough studies that highlight the correlation between poor indoor air quality and loss of performance and productivity of workers in an office setting.[104]  

Combining the Internet of Things (IoT) technology with real-time IAQ monitoring systems has  tremendously gained momentum and popularity as interventions can be done based on the real-time sensor data and thus help in the IAQ improvement.[105]   

Improvement measures

This section needs expansion. You can help by adding to it. (November 2023)

See also: Air purifier, Air conditioner, Air filter, Cleanroom, Particulates § Controlling technologies and measures, Pollution control, and Ventilation (architecture)

Further information: Fan (machine), Dehumidifier, and Heater

Indoor air quality can be addressed, achieved or maintained during the design of new buildings or as mitigating measures in existing buildings. A hierarchy of measures has been proposed by the Institute of Air Quality Management. It emphasises removing pollutant sources, reducing emissions from any remaining sources, disrupting pathways between sources and the people exposed, protecting people from exposure to pollutants, and removing people from areas with poor air quality.[106]

A report assisted by the Institute for Occupational Safety and Health of the German Social Accident Insurance can support in the systematic investigation of individual health problems arising at indoor workplaces, and in the identification of practical solutions.[107]

HVAC design

Main articles: HVAC, Air handler, and Ventilation (architecture)

This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources in this section. Unsourced material may be challenged and removed. (November 2019) (Learn how and when to remove this message)

Environmentally sustainable design concepts include aspects of commercial and residential heating, ventilation and air-conditioning (HVAC) technologies. Among several considerations, one of the topics attended to is the issue of indoor air quality throughout the design and construction stages of a building's life.

One technique to reduce energy consumption while maintaining adequate air quality, is demand controlled ventilation. Instead of setting throughput at a fixed air replacement rate, carbon dioxide sensors are used to control the rate dynamically, based on the emissions of actual building occupants.

One way of quantitatively ensuring the health of indoor air is by the frequency of effective turnover of interior air by replacement with outside air. In the UK, for example, classrooms are required to have 2.5 outdoor air changes per hour. In halls, gym, dining, and physiotherapy spaces, the ventilation should be sufficient to limit carbon dioxide to 1,500 ppm. In the US, ventilation in classrooms is based on the amount of outdoor air per occupant plus the amount of outdoor air per unit of floor area, not air changes per hour. Since carbon dioxide indoors comes from occupants and outdoor air, the adequacy of ventilation per occupant is indicated by the concentration indoors minus the concentration outdoors. The value of 615 ppm above the outdoor concentration indicates approximately 15 cubic feet per minute of outdoor air per adult occupant doing sedentary office work where outdoor air contains over 400 ppm[108] (global average as of 2023). In classrooms, the requirements in the ASHRAE standard 62.1, Ventilation for Acceptable Indoor Air Quality, would typically result in about 3 air changes per hour, depending on the occupant density. As the occupants are not the only source of pollutants, outdoor air ventilation may need to be higher when unusual or strong sources of pollution exist indoors.

When outdoor air is polluted, bringing in more outdoor air can actually worsen the overall quality of the indoor air and exacerbate some occupant symptoms related to outdoor air pollution. Generally, outdoor country air is better than indoor city air.

The use of air filters can trap some of the air pollutants. Portable room air cleaners with HEPA filters can be used if ventilation poor or outside air has high level of PM 2.5.[107] Air filters are used to reduce the amount of dust that reaches the wet coils. Dust can serve as food to grow molds on the wet coils and ducts and can reduce the efficiency of the coils.

The use of trickle vents on windows is also valuable to maintain constant ventilation. They can help prevent mold and allergen build up in the home or workplace. They can also reduce the spread of some respiratory infections.[109]

Moisture management and humidity control requires operating HVAC systems as designed. Moisture management and humidity control may conflict with efforts to conserve energy. For example, moisture management and humidity control requires systems to be set to supply make-up air at lower temperatures (design levels), instead of the higher temperatures sometimes used to conserve energy in cooling-dominated climate conditions. However, for most of the US and many parts of Europe and Japan, during the majority of hours of the year, outdoor air temperatures are cool enough that the air does not need further cooling to provide thermal comfort indoors. However, high humidity outdoors creates the need for careful attention to humidity levels indoors. High humidity give rise to mold growth and moisture indoors is associated with a higher prevalence of occupant respiratory problems.

The "dew point temperature" is an absolute measure of the moisture in air. Some facilities are being designed with the design dew points in the lower 50s °F, and some in the upper and lower 40s °F. Some facilities are being designed using desiccant wheels with gas-fired heaters to dry out the wheel enough to get the required dew points. On those systems, after the moisture is removed from the make-up air, a cooling coil is used to lower the temperature to the desired level.

Commercial buildings, and sometimes residential, are often kept under slightly positive air pressure relative to the outdoors to reduce infiltration. Limiting infiltration helps with moisture management and humidity control.

Dilution of indoor pollutants with outdoor air is effective to the extent that outdoor air is free of harmful pollutants. Ozone in outdoor air occurs indoors at reduced concentrations because ozone is highly reactive with many chemicals found indoors. The products of the reactions between ozone and many common indoor pollutants include organic compounds that may be more odorous, irritating, or toxic than those from which they are formed. These products of ozone chemistry include formaldehyde, higher molecular weight aldehydes, acidic aerosols, and fine and ultrafine particles, among others. The higher the outdoor ventilation rate, the higher the indoor ozone concentration and the more likely the reactions will occur, but even at low levels, the reactions will take place. This suggests that ozone should be removed from ventilation air, especially in areas where outdoor ozone levels are frequently high.

Effect of indoor plants

Spider plants (Chlorophytum comosum) absorb some airborne contaminants.

Houseplants together with the medium in which they are grown can reduce components of indoor air pollution, particularly volatile organic compounds (VOC) such as benzene, toluene, and xylene. Plants remove CO2 and release oxygen and water, although the quantitative impact for house plants is small. The interest in using potted plants for removing VOCs was sparked by a 1989 NASA study conducted in sealed chambers designed to replicate the environment on space stations. However, these results suffered from poor replication[110] and are not applicable to typical buildings, where outdoor-to-indoor air exchange already removes VOCs at a rate that could only be matched by the placement of 10–1000 plants/m2 of a building's floor space.[111]

Plants also appear to reduce airborne microbes and molds, and to increase humidity.[112] However, the increased humidity can itself lead to increased levels of mold and even VOCs.[113]

Since extremely high humidity is associated with increased mold growth, allergic responses, and respiratory responses, the presence of additional moisture from houseplants may not be desirable in all indoor settings if watering is done inappropriately.[114]

Institutional programs

EPA graphic about asthma triggers

The topic of IAQ has become popular due to the greater awareness of health problems caused by mold and triggers to asthma and allergies.

In the US, the Environmental Protection Agency (EPA) has developed an "IAQ Tools for Schools" program to help improve the indoor environmental conditions in educational institutions. The National Institute for Occupational Safety and Health conducts Health Hazard Evaluations (HHEs) in workplaces at the request of employees, authorized representative of employees, or employers, to determine whether any substance normally found in the place of employment has potentially toxic effects, including indoor air quality.[115]

A variety of scientists work in the field of indoor air quality, including chemists, physicists, mechanical engineers, biologists, bacteriologists, epidemiologists, and computer scientists. Some of these professionals are certified by organizations such as the American Industrial Hygiene Association, the American Indoor Air Quality Council and the Indoor Environmental Air Quality Council.

In the UK, under the Department for Environment Food and Rural Affairs, the Air Quality Expert Group considers current knowledge on indoor air quality and provides advice to government and devolved administration ministers.[116]

At the international level, the International Society of Indoor Air Quality and Climate (ISIAQ), formed in 1991, organizes two major conferences, the Indoor Air and the Healthy Buildings series.[117]

See also


  1. ^ Carroll, GT; Kirschman, DL; Mammana, A (2022). "Increased CO2 levels in the operating room correlate with the number of healthcare workers present: an imperative for intentional crowd control". Patient Safety in Surgery. 16 (35): 35. doi:10.1186/s13037-022-00343-8. PMC 9672642. PMID 36397098.
  2. ^ KMC Controls (September 24, 2015). "What's Your IQ on IAQ and IEQ?". Archived from the original on April 12, 2021. Retrieved April 12, 2021.[unreliable source?]
  3. ^ Bruce, N; Perez-Padilla, R; Albalak, R (2000). "Indoor air pollution in developing countries: a major environmental and public health challenge". Bulletin of the World Health Organization. 78 (9): 1078–92. PMC 2560841. PMID 11019457.
  4. ^ "Household air pollution and health: fact sheet". WHO. May 8, 2018. Archived from the original on November 12, 2021. Retrieved November 21, 2020.
  5. ^ Ritchie, Hannah; Roser, Max (2019). "Access to Energy". Our World in Data. Archived from the original on November 1, 2021. Retrieved April 1, 2021. According to the Global Burden of Disease study 1.6 million people died prematurely in 2017 as a result of indoor air pollution ... But it's worth noting that the WHO publishes a substantially larger number of indoor air pollution deaths..
  6. ^ Klepeis, Neil E; Nelson, William C; Ott, Wayne R; Robinson, John P; Tsang, Andy M; Switzer, Paul; Behar, Joseph V; Hern, Stephen C; Engelmann, William H (July 2001). "The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants". Journal of Exposure Science & Environmental Epidemiology. 11 (3): 231–252. doi:10.1038/sj.jea.7500165. PMID 11477521. S2CID 22445147. Archived from the original on March 28, 2023. Retrieved March 30, 2024.
  7. ^ U.S. Environmental Protection Agency. Office equipment: design, indoor air emissions, and pollution prevention opportunities. Air and Energy Engineering Research Laboratory, Research Triangle Park, 1995.
  8. ^ U.S. Environmental Protection Agency. Unfinished business: a comparative assessment of environmental problems, EPA-230/2-87-025a-e (NTIS PB88-127030). Office of Policy, Planning and Evaluation, Washington, DC, 1987.
  9. ^ Klepeis, Neil E; Nelson, William C; Ott, Wayne R; Robinson, John P; Tsang, Andy M; Switzer, Paul; Behar, Joseph V; Hern, Stephen C; Engelmann, William H (July 1, 2001). "The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants". Journal of Exposure Science & Environmental Epidemiology. 11 (3): 231–252. doi:10.1038/sj.jea.7500165. ISSN 1559-0631. PMID 11477521. Archived from the original on November 13, 2023. Retrieved November 13, 2023.
  10. ^ "Combined or multiple exposure to health stressors in indoor built environments: an evidence-based review prepared for the WHO training workshop "Multiple environmental exposures and risks": 16–18 October 2013, Bonn, Germany". World Health Organization. Regional Office for Europe. 2014. Archived from the original on November 6, 2023. Retrieved April 10, 2024.
  11. ^ "Household air pollution". World Health Organization. December 15, 2023. Archived from the original on November 12, 2021. Retrieved April 10, 2024.
  12. ^ Clark, Sierra N.; Lam, Holly C. Y.; Goode, Emma-Jane; Marczylo, Emma L.; Exley, Karen S.; Dimitroulopoulou, Sani (August 2, 2023). "The Burden of Respiratory Disease from Formaldehyde, Damp and Mould in English Housing". Environments. 10 (8): 136. doi:10.3390/environments10080136. ISSN 2076-3298.
  13. ^ "Chief Medical Officer (CMO): annual reports". GOV.UK. November 16, 2023. Retrieved May 5, 2024.
  14. ^ "Project information | Indoor air quality at home | Quality standards | NICE". Retrieved May 5, 2024.
  15. ^ "The inside story: Health effects of indoor air quality on children and young people". RCPCH. Retrieved May 5, 2024.
  16. ^ Halios, Christos H.; Landeg-Cox, Charlotte; Lowther, Scott D.; Middleton, Alice; Marczylo, Tim; Dimitroulopoulou, Sani (September 15, 2022). "Chemicals in European residences – Part I: A review of emissions, concentrations and health effects of volatile organic compounds (VOCs)". Science of the Total Environment. 839: 156201. doi:10.1016/j.scitotenv.2022.156201. ISSN 0048-9697. PMID 35623519.
  17. ^ "Literature review on chemical pollutants in indoor air in public settings for children and overview of their health effects with a focus on schools, kindergartens and day-care centres". Retrieved May 5, 2024.
  18. ^ Burge, P S (February 2004). "Sick building syndrome". Occupational and Environmental Medicine. 61 (2): 185–190. doi:10.1136/oem.2003.008813. PMC 1740708. PMID 14739390.
  19. ^ Apte, K; Salvi, S (2016). "Household air pollution and its effects on health". F1000Research. 5: 2593. doi:10.12688/f1000research.7552.1. PMC 5089137. PMID 27853506. Burning of natural gas not only produces a variety of gases such as sulfur oxides, mercury compounds, and particulate matter but also leads to the production of nitrogen oxides, primarily nitrogen dioxide...The burning of biomass fuel or any other fossil fuel increases the concentration of black carbon in the air
  20. ^ "Improved Clean Cookstoves". Project Drawdown. February 7, 2020. Archived from the original on December 15, 2021. Retrieved December 5, 2020.
  21. ^ WHO indoor air quality guidelines: household fuel combustion. Geneva: World Health Organization. 2014. ISBN 978-92-4-154888-5.
  22. ^ "Clearing the Air: Gas Cooking and Pollution in European Homes". CLASP. November 8, 2023. Retrieved May 5, 2024.
  23. ^ Seals, Brady; Krasner, Andee. "Gas Stoves: Health and Air Quality Impacts and Solutions". RMI. Retrieved May 5, 2024.
  24. ^ a b c Myers, Isabella (February 2022). The efficient operation of regulation and legislation: An holistic approach to understanding the effect of Carbon Monoxide on mortality (PDF). CO Research Trust.
  25. ^ a b c Penney, David; Benignus, Vernon; Kephalopoulos, Stylianos; Kotzias, Dimitrios; Kleinman, Michael; Verrier, Agnes (2010), "Carbon monoxide", WHO Guidelines for Indoor Air Quality: Selected Pollutants, World Health Organization, ISBN 978-92-890-0213-4, OCLC 696099951, archived from the original on March 8, 2021, retrieved March 18, 2024
  26. ^ "Carbon monoxide: toxicological overview". UK Health Security Agency. May 24, 2022. Retrieved April 17, 2024.
  27. ^ a b c WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide (PDF). World Health Organization. 2021. hdl:10665/345329. ISBN 978-92-4-003422-8.[page needed]
  28. ^ a b Soleimani, Farshid; Dobaradaran, Sina; De-la-Torre, Gabriel E.; Schmidt, Torsten C.; Saeedi, Reza (March 2022). "Content of toxic components of cigarette, cigarette smoke vs cigarette butts: A comprehensive systematic review". Science of the Total Environment. 813: 152667. Bibcode:2022ScTEn.813o2667S. doi:10.1016/j.scitotenv.2021.152667. PMID 34963586.
  29. ^ "Considering smoking as an air pollution problem for environmental health | Environmental Performance Index". Archived from the original on September 25, 2018. Retrieved March 21, 2018.
  30. ^ Arfaeinia, Hossein; Ghaemi, Maryam; Jahantigh, Anis; Soleimani, Farshid; Hashemi, Hassan (June 12, 2023). "Secondhand and thirdhand smoke: a review on chemical contents, exposure routes, and protective strategies". Environmental Science and Pollution Research. 30 (32): 78017–78029. Bibcode:2023ESPR...3078017A. doi:10.1007/s11356-023-28128-1. PMC 10258487. PMID 37306877.
  31. ^ Arfaeinia, Hossein; Ghaemi, Maryam; Jahantigh, Anis; Soleimani, Farshid; Hashemi, Hassan (June 12, 2023). "Secondhand and thirdhand smoke: a review on chemical contents, exposure routes, and protective strategies". Environmental Science and Pollution Research. 30 (32): 78017–78029. Bibcode:2023ESPR...3078017A. doi:10.1007/s11356-023-28128-1. ISSN 1614-7499. PMC 10258487. PMID 37306877.
  32. ^ Health, CDC's Office on Smoking and (May 9, 2018). "Smoking and Tobacco Use; Fact Sheet; Secondhand Smoke". Smoking and Tobacco Use. Archived from the original on December 15, 2021. Retrieved January 14, 2019.
  33. ^ Fernández, E; Ballbè, M; Sureda, X; Fu, M; Saltó, E; Martínez-Sánchez, JM (December 2015). "Particulate Matter from Electronic Cigarettes and Conventional Cigarettes: a Systematic Review and Observational Study". Current Environmental Health Reports. 2 (4): 423–9. doi:10.1007/s40572-015-0072-x. PMID 26452675.
  34. ^ Vu, Tuan V.; Harrison, Roy M. (May 8, 2019). "Chemical and Physical Properties of Indoor Aerosols". In Harrison, R. M.; Hester, R. E. (eds.). Indoor Air Pollution. The Royal Society of Chemistry (published 2019). ISBN 978-1-78801-803-6.((cite book)): CS1 maint: date and year (link)
  35. ^ Abdullahi, Karimatu L.; Delgado-Saborit, Juana Maria; Harrison, Roy M. (February 13, 2013). "Emissions and indoor concentrations of particulate matter and its specific chemical components from cooking: A review". Atmospheric Environment. 71: 260–294. Bibcode:2013AtmEn..71..260A. doi:10.1016/j.atmosenv.2013.01.061. Archived from the original on May 21, 2023. Retrieved April 11, 2024.
  36. ^ Patel, Sameer; Sankhyan, Sumit; Boedicker, Erin K.; DeCarlo, Peter F.; Farmer, Delphine K.; Goldstein, Allen H.; Katz, Erin F.; Nazaroff, William W; Tian, Yilin; Vanhanen, Joonas; Vance, Marina E. (June 16, 2020). "Indoor Particulate Matter during HOMEChem: Concentrations, Size Distributions, and Exposures". Environmental Science & Technology. 54 (12): 7107–7116. Bibcode:2020EnST...54.7107P. doi:10.1021/acs.est.0c00740. ISSN 0013-936X. PMID 32391692. Archived from the original on April 28, 2023. Retrieved April 11, 2024.
  37. ^ Azarmi, Farhad; Kumar, Prashant (July 2016). "Ambient exposure to coarse and fine particle emissions from building demolition". Atmospheric Environment. 137: 62–79. Bibcode:2016AtmEn.137...62A. doi:10.1016/j.atmosenv.2016.04.029.
  38. ^ You, Bo; Zhou, Wei; Li, Junyao; Li, Zhijie; Sun, Yele (November 4, 2022). "A review of indoor Gaseous organic compounds and human chemical Exposure: Insights from Real-time measurements". Environment International. 170: 107611. Bibcode:2022EnInt.17007611Y. doi:10.1016/j.envint.2022.107611. PMID 36335895.
  39. ^ Weschler, Charles J.; Carslaw, Nicola (March 6, 2018). "Indoor Chemistry". Environmental Science & Technology. 52 (5): 2419–2428. Bibcode:2018EnST...52.2419W. doi:10.1021/acs.est.7b06387. ISSN 0013-936X. PMID 29402076. Archived from the original on November 15, 2023. Retrieved April 11, 2024.
  40. ^ a b Carter, Toby J.; Poppendieck, Dustin G.; Shaw, David; Carslaw, Nicola (January 16, 2023). "A Modelling Study of Indoor Air Chemistry: The Surface Interactions of Ozone and Hydrogen Peroxide". Atmospheric Environment. 297: 119598. Bibcode:2023AtmEn.29719598C. doi:10.1016/j.atmosenv.2023.119598. Archived from the original on May 23, 2023. Retrieved April 11, 2024.
  41. ^ Tsai, Wen-Tien (March 26, 2019). "An overview of health hazards of volatile organic compounds regulated as indoor air pollutants". Reviews on Environmental Health. 34 (1): 81–89. doi:10.1515/reveh-2018-0046. PMID 30854833.
  42. ^ "U.S. EPA IAQ – Organic chemicals". August 5, 2010. Archived from the original on September 9, 2015. Retrieved March 2, 2012.
  43. ^ a b Davies, Helen L.; O'Leary, Catherine; Dillon, Terry; Shaw, David R.; Shaw, Marvin; Mehra, Archit; Phillips, Gavin; Carslaw, Nicola (August 14, 2023). "A measurement and modelling investigation of the indoor air chemistry following cooking activities". Environmental Science: Processes & Impacts. 25 (9): 1532–1548. doi:10.1039/D3EM00167A. ISSN 2050-7887. PMID 37609942.
  44. ^ a b c Harding-Smith, Ellen; Shaw, David R.; Shaw, Marvin; Dillon, Terry J.; Carslaw, Nicola (January 23, 2024). "Does green mean clean? Volatile organic emissions from regular versus green cleaning products". Environmental Science: Processes & Impacts. 26 (2): 436–450. doi:10.1039/D3EM00439B. ISSN 2050-7887. PMID 38258874.
  45. ^ Lebel, Eric D.; Michanowicz, Drew R.; Bilsback, Kelsey R.; Hill, Lee Ann L.; Goldman, Jackson S. W.; Domen, Jeremy K.; Jaeger, Jessie M.; Ruiz, Angélica; Shonkoff, Seth B. C. (November 15, 2022). "Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California". Environmental Science & Technology. 56 (22): 15828–15838. Bibcode:2022EnST...5615828L. doi:10.1021/acs.est.2c02581. ISSN 0013-936X. PMC 9671046. PMID 36263944.
  46. ^ "About VOCs". January 21, 2013. Archived from the original on January 21, 2013. Retrieved September 16, 2019.
  47. ^ Oanh, Nguyen Thi Kim; Hung, Yung-Tse (2005). "Indoor Air Pollution Control". Advanced Air and Noise Pollution Control. Handbook of Environmental Engineering. Vol. 2. pp. 237–272. doi:10.1007/978-1-59259-779-6_7. ISBN 978-1-58829-359-6.
  48. ^ "Emicode". Archived from the original on September 24, 2015. Retrieved March 2, 2012.
  49. ^ "M1". Archived from the original on September 24, 2015. Retrieved March 2, 2012.
  50. ^ "Blue Angel". Archived from the original on September 24, 2015. Retrieved March 2, 2012.
  51. ^ "Indoor Air Comfort". Indoor Air Comfort. Archived from the original on February 1, 2011. Retrieved March 2, 2012.
  52. ^ "CDPH Section 01350". Archived from the original on September 24, 2015. Retrieved March 2, 2012.
  53. ^ a b "Smelly Moldy Houses". Archived from the original on December 15, 2021. Retrieved August 2, 2014.
  54. ^ Meruva, N. K.; Penn, J. M.; Farthing, D. E. (November 2004). "Rapid identification of microbial VOCs from tobacco molds using closed-loop stripping and gas chromatography/time-of-flight mass spectrometry". J Ind Microbiol Biotechnol. 31 (10): 482–8. doi:10.1007/s10295-004-0175-0. PMID 15517467. S2CID 32543591.
  55. ^ "Atmospheric carbon dioxide passes 400 ppm everywhere". Physics Today. 2016. doi:10.1063/pt.5.029904.
  56. ^ Weschler, Charles J. (December 2000). "Ozone in Indoor Environments: Concentration and Chemistry: Ozone in Indoor Environments". Indoor Air. 10 (4): 269–288. doi:10.1034/j.1600-0668.2000.010004269.x. PMID 11089331. Archived from the original on April 15, 2024. Retrieved April 11, 2024.
  57. ^ Weschler, Charles J.; Nazaroff, William W (February 22, 2023). "Human skin oil: a major ozone reactant indoors". Environmental Science: Atmospheres. 3 (4): 640–661. doi:10.1039/D3EA00008G. ISSN 2634-3606. Archived from the original on April 15, 2024. Retrieved April 11, 2024.
  58. ^ Kumar, Prashant; Kalaiarasan, Gopinath; Porter, Alexandra E.; Pinna, Alessandra; Kłosowski, Michał M.; Demokritou, Philip; Chung, Kian Fan; Pain, Christopher; Arvind, D. K.; Arcucci, Rossella; Adcock, Ian M.; Dilliway, Claire (February 20, 2021). "An overview of methods of fine and ultrafine particle collection for physicochemical characterisation and toxicity assessments". Science of the Total Environment. 756: 143553. Bibcode:2021ScTEn.756n3553K. doi:10.1016/j.scitotenv.2020.143553. hdl:10044/1/84518. PMID 33239200. S2CID 227176222.
  59. ^ Apte, M. G.; Buchanan, I. S. H.; Mendell, M. J. (April 2008). "Outdoor ozone and building-related symptoms in the BASE study". Indoor Air. 18 (2): 156–170. Bibcode:2008InAir..18..156A. doi:10.1111/j.1600-0668.2008.00521.x. PMID 18333994.
  60. ^ "Eight-hour Average Ozone Concentrations | Ground-level Ozone | New England | US EPA". United States Environmental Protection Agency. Archived from the original on December 15, 2021. Retrieved September 16, 2019.
  61. ^ a b c Park, J. H.; Cox-Ganser, J. M. (2011). "Meta-Mold exposure and respiratory health in damp indoor environments". Frontiers in Bioscience. 3 (2): 757–771. doi:10.2741/e284. PMID 21196349.
  62. ^ "CDC – Mold – General Information – Facts About Mold and Dampness". December 4, 2018. Archived from the original on December 16, 2019. Retrieved June 23, 2017.
  63. ^ Singh, Dr Jagjit; Singh, Jagjit, eds. (1994). Building Mycology (1 ed.). Taylor & Francis. doi:10.4324/9780203974735. ISBN 978-1-135-82462-4.
  64. ^ a b Clarke, J.A; Johnstone, C.M; Kelly, N.J; McLean, R.C; anderson, J.A; Rowan, N.J; Smith, J.E (January 20, 1999). "A technique for the prediction of the conditions leading to mould growth in buildings". Building and Environment. 34 (4): 515–521. Bibcode:1999BuEnv..34..515C. doi:10.1016/S0360-1323(98)00023-7. Archived from the original on October 26, 2022. Retrieved April 10, 2024.
  65. ^ Vereecken, Evy; Roels, Staf (November 15, 2011). "Review of mould prediction models and their influence on mould risk evaluation". Building and Environment. 51: 296–310. doi:10.1016/j.buildenv.2011.11.003. Archived from the original on March 2, 2024. Retrieved April 11, 2024.
  66. ^ BS 5250:2021 - Management of moisture in buildings. Code of practice. British Standards Institution (BSI). October 31, 2021. ISBN 978-0-539-18975-9.
  67. ^ Madgwick, Della; Wood, Hannah (August 8, 2016). "The problem of clothes drying in new homes in the UK". Structural Survey. 34 (4/5): 320–330. doi:10.1108/SS-10-2015-0048. ISSN 0263-080X. Archived from the original on May 7, 2021. Retrieved April 11, 2024.
  68. ^ May, Neil; McGilligan, Charles; Ucci, Marcella (2017). "Health and Moisture in Buildings" (PDF). UK Centre for Moisture in Buildings. Archived (PDF) from the original on April 11, 2024. Retrieved April 11, 2024.
  69. ^ "Understanding and addressing the health risks of damp and mould in the home". GOV.UK. September 7, 2023. Archived from the original on April 10, 2024. Retrieved April 11, 2024.
  70. ^ Microbiology of the Indoor Environment Archived July 23, 2011, at the Wayback Machine,
  71. ^ Azuma, Kenichi; Kagi, Naoki; Yanagi, U.; Osawa, Haruki (December 2018). "Effects of low-level inhalation exposure to carbon dioxide in indoor environments: A short review on human health and psychomotor performance". Environment International. 121 (Pt 1): 51–56. Bibcode:2018EnInt.121...51A. doi:10.1016/j.envint.2018.08.059. PMID 30172928.
  72. ^ Du, Bowen; Tandoc, Michael (June 19, 2020). "Indoor CO2 concentrations and cognitive function: A critical review". International Journal of Indoor Environment and Health. 30 (6): 1067–1082. Bibcode:2020InAir..30.1067D. doi:10.1111/ina.12706. PMID 32557862. S2CID 219915861.
  73. ^ Fan, Yuejie; Cao, Xiaodong; Zhang, Jie; Lai, Dayi; Pang, Liping (June 1, 2023). "Short-term exposure to indoor carbon dioxide and cognitive task performance: A systematic review and meta-analysis". Building and Environment. 237: 110331. Bibcode:2023BuEnv.23710331F. doi:10.1016/j.buildenv.2023.110331.
  74. ^ a b Lowther, Scott D.; Dimitroulopoulou, Sani; Foxall, Kerry; Shrubsole, Clive; Cheek, Emily; Gadeberg, Britta; Sepai, Ovnair (November 16, 2021). "Low Level Carbon Dioxide Indoors—A Pollution Indicator or a Pollutant? A Health-Based Perspective". Environments. 8 (11): 125. doi:10.3390/environments8110125. ISSN 2076-3298.
  75. ^ Persily, Andrew (July 2022). "Development and application of an indoor carbon dioxide metric". Indoor Air. 32 (7): e13059. doi:10.1111/ina.13059. PMID 35904382.
  76. ^ "Indoor Environmental Quality: HVAC Management | NIOSH | CDC". February 25, 2022. Archived from the original on April 1, 2022. Retrieved April 1, 2022.
  77. ^ Indoor Environmental Quality: Building Ventilation Archived January 20, 2022, at the Wayback Machine. National Institute for Occupational Safety and Health. Accessed October 8, 2008.
  78. ^ "SAMHE - Schools' Air quality Monitoring for Health and Education". Archived from the original on March 18, 2024. Retrieved March 18, 2024.
  79. ^ "Document Display | NEPIS | US EPA". Archived from the original on November 16, 2023. Retrieved October 19, 2023.
  80. ^ Zeeb & Shannoun 2009, p. 3.
  81. ^ C.Michael Hogan and Sjaak Slanina. 2010, Air pollution. Encyclopedia of Earth Archived October 12, 2006, at the Wayback Machine. eds. Sidney Draggan and Cutler Cleveland. National Council for Science and the Environment. Washington DC
  82. ^ "Radon Mitigation Methods". Radon Solution—Raising Radon Awareness. Archived from the original on December 15, 2008. Retrieved December 2, 2008.
  83. ^ Zeeb & Shannoun 2009, p. [page needed].
  84. ^ "Basic radon facts" (PDF). US Environmental Protection Agency. Archived (PDF) from the original on January 13, 2022. Retrieved September 18, 2018. Public Domain This article incorporates text from this source, which is in the public domain.
  85. ^ "Radon Action Level and Target Level". UKradon. Archived from the original on March 18, 2024. Retrieved March 18, 2024.
  86. ^ "Radon Zone Map (with State Information)". U.S. Environmental Protection Agency. Archived from the original on April 1, 2023. Retrieved April 10, 2024.
  87. ^ "UK maps of radon". UKradon. Archived from the original on March 7, 2024. Retrieved April 10, 2024.
  88. ^ "Radon map of Australia". Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Archived from the original on March 20, 2024. Retrieved April 10, 2024.
  89. ^ "Climate Change 2021: The Physical Science Basis". Intergovernmental Panel on Climate Change. Archived (PDF) from the original on May 26, 2023. Retrieved April 15, 2024.
  90. ^ Gherasim, Alina; Lee, Alison G.; Bernstein, Jonathan A. (November 14, 2023). "Impact of Climate Change on Indoor Air Quality". Immunology and Allergy Clinics of North America. 44 (1): 55–73. doi:10.1016/j.iac.2023.09.001. PMID 37973260. Archived from the original on November 15, 2023. Retrieved April 15, 2024.
  91. ^ Lacressonnière, Gwendoline; Watson, Laura; Gauss, Michael; Engardt, Magnuz; Andersson, Camilla; Beekmann, Matthias; Colette, Augustin; Foret, Gilles; Josse, Béatrice; Marécal, Virginie; Nyiri, Agnes; Siour, Guillaume; Sobolowski, Stefan; Vautard, Robert (February 1, 2017). "Particulate matter air pollution in Europe in a +2 °C warming world". Atmospheric Environment. 154: 129–140. Bibcode:2017AtmEn.154..129L. doi:10.1016/j.atmosenv.2017.01.037. Archived from the original on November 17, 2023. Retrieved April 15, 2024.
  92. ^ Lee, J; Lewis, A; Monks, P; Jacob, M; Hamilton, J; Hopkins, J; Watson, N; Saxton, J; Ennis, C; Carpenter, L (September 26, 2006). "Ozone photochemistry and elevated isoprene during the UK heatwave of august 2003". Atmospheric Environment. 40 (39): 7598–7613. Bibcode:2006AtmEn..40.7598L. doi:10.1016/j.atmosenv.2006.06.057. Archived from the original on October 26, 2022. Retrieved April 15, 2024.
  93. ^ Salthammer, Tunga; Schieweck, Alexandra; Gu, Jianwei; Ameri, Shaghayegh; Uhde, Erik (August 7, 2018). "Future trends in ambient air pollution and climate in Germany – Implications for the indoor environment". Building and Environment. 143: 661–670. Bibcode:2018BuEnv.143..661S. doi:10.1016/j.buildenv.2018.07.050.
  94. ^ Zhong, L.; Lee, C.-S.; Haghighat, F. (December 1, 2016). "Indoor ozone and climate change". Sustainable Cities and Society. 28: 466–472. doi:10.1016/j.scs.2016.08.020. Archived from the original on November 28, 2022. Retrieved April 15, 2024.
  95. ^ Zhao, Jiangyue; Uhde, Erik; Salthammer, Tunga; Antretter, Florian; Shaw, David; Carslaw, Nicola; Schieweck, Alexandra (December 9, 2023). "Long-term prediction of the effects of climate change on indoor climate and air quality". Environmental Research. 243: 117804. doi:10.1016/j.envres.2023.117804. PMID 38042519.
  96. ^ Niculita-Hirzel, Hélène (March 16, 2022). "Latest Trends in Pollutant Accumulations at Threatening Levels in Energy-Efficient Residential Buildings with and without Mechanical Ventilation: A Review". International Journal of Environmental Research and Public Health. 19 (6): 3538. doi:10.3390/ijerph19063538. ISSN 1660-4601. PMC 8951331. PMID 35329223.
  97. ^ UK Health Security Agency (2024) [1 September 2012]. "Chapter 5: Impact of climate change policies on indoor environmental quality and health in UK housing". Health Effects of Climate Change (HECC) in the UK: 2023 report (published January 15, 2024).
  98. ^ World Health Organization, ed. (2010). Who guidelines for indoor air quality: selected pollutants. Copenhagen: WHO. ISBN 978-92-890-0213-4. OCLC 696099951.
  99. ^ "Air quality: UK guidelines for volatile organic compounds in indoor spaces". Public Health England. September 13, 2019. Retrieved April 17, 2024.
  100. ^ "Home - IEQ Guidelines". Retrieved April 17, 2024.
  101. ^ Toyinbo, Oluyemi; Hägerhed, Linda; Dimitroulopoulou, Sani; Dudzinska, Marzenna; Emmerich, Steven; Hemming, David; Park, Ju-Hyeong; Haverinen-Shaughnessy, Ulla; the Scientific Technical Committee 34 of the International Society of Indoor Air Quality, Climate (April 19, 2022). "Open database for international and national indoor environmental quality guidelines". Indoor Air. 32 (4): e13028. doi:10.1111/ina.13028. ISSN 0905-6947. PMID 35481936.((cite journal)): CS1 maint: numeric names: authors list (link)
  102. ^ Dimitroulopoulou, Sani; Dudzińska, Marzenna R.; Gunnarsen, Lars; Hägerhed, Linda; Maula, Henna; Singh, Raja; Toyinbo, Oluyemi; Haverinen-Shaughnessy, Ulla (August 4, 2023). "Indoor air quality guidelines from across the world: An appraisal considering energy saving, health, productivity, and comfort". Environment International. 178: 108127. Bibcode:2023EnInt.17808127D. doi:10.1016/j.envint.2023.108127. PMID 37544267.
  103. ^ Pitarma, Rui; Marques, Gonçalo; Ferreira, Bárbara Roque (February 2017). "Monitoring Indoor Air Quality for Enhanced Occupational Health". Journal of Medical Systems. 41 (2): 23. doi:10.1007/s10916-016-0667-2. PMID 28000117. S2CID 7372403.
  104. ^ Wyon, D. P. (August 2004). "The effects of indoor air quality on performance and productivity: The effects of IAQ on performance and productivity". Indoor Air. 14: 92–101. doi:10.1111/j.1600-0668.2004.00278.x. PMID 15330777.
  105. ^ Son, Young Joo; Pope, Zachary C.; Pantelic, Jovan (September 2023). "Perceived air quality and satisfaction during implementation of an automated indoor air quality monitoring and control system". Building and Environment. 243: 110713. Bibcode:2023BuEnv.24310713S. doi:10.1016/j.buildenv.2023.110713.
  106. ^ IAQM (2021). Indoor Air Quality Guidance: Assessment, Monitoring, Modelling and Mitigation (PDF) (Version 0.1 ed.). London: Institute of Air Quality Management.
  107. ^ a b Institute for Occupational Safety and Health of the German Social Accident Insurance. "Indoor workplaces – Recommended procedure for the investigation of working environment". Archived from the original on November 3, 2021. Retrieved June 10, 2020.
  108. ^ "Climate Change: Atmospheric Carbon Dioxide | NOAA". April 9, 2024. Retrieved May 6, 2024.
  109. ^ "Ventilation to reduce the spread of respiratory infections, including COVID-19". GOV.UK. August 2, 2022. Archived from the original on January 18, 2024. Retrieved April 15, 2024.
  110. ^ Dela Cruz, Majbrit; Christensen, Jan H.; Thomsen, Jane Dyrhauge; Müller, Renate (December 2014). "Can ornamental potted plants remove volatile organic compounds from indoor air? — a review". Environmental Science and Pollution Research. 21 (24): 13909–13928. Bibcode:2014ESPR...2113909D. doi:10.1007/s11356-014-3240-x. PMID 25056742. S2CID 207272189.
  111. ^ Cummings, Bryan E.; Waring, Michael S. (March 2020). "Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies". Journal of Exposure Science & Environmental Epidemiology. 30 (2): 253–261. doi:10.1038/s41370-019-0175-9. PMID 31695112. S2CID 207911697.
  112. ^ Wolverton, B. C.; Wolverton, J. D. (1996). "Interior plants: their influence on airborne microbes inside energy-efficient buildings". Journal of the Mississippi Academy of Sciences. 41 (2): 100–105.
  113. ^ US EPA, OAR (July 16, 2013). "Mold". US EPA. Archived from the original on May 18, 2020. Retrieved September 16, 2019.
  114. ^ Institute of Medicine (US) Committee on Damp Indoor Spaces and Health (2004). Damp Indoor Spaces and Health. National Academies Press. ISBN 978-0-309-09193-0. PMID 25009878. Archived from the original on January 19, 2023. Retrieved March 30, 2024.[page needed]
  115. ^ "Indoor Environmental Quality". Washington, DC: US National Institute for Occupational Safety and Health. Archived from the original on December 3, 2013. Retrieved May 17, 2013.
  116. ^ Lewis, Alastair C; Allan, James; Carslaw, David; Carruthers, David; Fuller, Gary; Harrison, Roy; Heal, Mathew; Nemitz, Eiko; Reeves, Claire (2022). Indoor Air Quality (PDF) (Report). Air Quality Expert Group. doi:10.5281/zenodo.6523605. Archived (PDF) from the original on June 5, 2023. Retrieved April 15, 2024.
  117. ^ "Isiaq.Org". International Society of Indoor Air Quality and Climate. Archived from the original on January 21, 2022. Retrieved March 2, 2012.


Articles, radio segments, web pages

Further reading