Indoor air quality

Common pollutants

Secondhand smoke is tobacco smoke which affects people other than the 'active' smoker. Second-hand tobacco smoke includes both a gaseous and a particulate phase, with particular hazards arising from levels of carbon monoxide as specified below and very small particulates fine particular matter at especially PM2.5 size, and PM10 which get into the bronchioles and alveoles in the lung. The onlymethod to improve indoor air quality as regards secondhand smoke is to eliminate smoking indoors. Indoor e-cigarette usage also increases home particulate matter concentrations.

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. Around 3 billion people cook over open fires or on rudimentary cook stoves. Cooking fuels are coal, wood, animal dung, and crop residues.

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 inbuilding materials themselves. Radon is probably the almost pervasive serious hazard for indoor air in the United States and Europe, and is probably responsible for tens of thousands of deaths from lung cancer regarded and sent separately. year. There are relatively simple test kits for do-it-yourself radon gas testing, but if a home is for sale the testing must be done by a licensed grown-up in some U.S. states. Radon gas enters buildings as a soil gas and is a heavy gas and thus will tend to accumulate at the lowest level. Radon may also be exposed 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. The half life for radon is 3.8 days, indicating that one time 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. They are usually cost effective and can greatly reduce or even eliminate the contamination and the associated health risks.

Radon is measured in picocuries per liter of air pCi/L, a measurement of radioactivity. In the United States, the average indoor radon level is about 1.3 pCi/L. The average outdoor level is approximately 0.4 pCi/L. The U.S. Surgeon General and EPA recommend fixing homes with radon levels at or above 4 pCi/L. EPA also recommends that people think about fixing their homes for radon levels between 2 pCi/L and 4 pCi/L.

These biological chemicals can arise from a host of means, but there are two common classes: a moisture induced growth of mold colonies and b natural substances released into the air such as animal dander and plant pollen. Mold is always associated with moisture, and its growth can be inhibited by keeping humidity levels below 50%. Moisture buildup inside buildings may occur from water penetrating compromised areas of the building envelope or skin, from plumbing leaks, from condensation due to improper ventilation, or from ground moisture penetrating a building part. Even something as simple as drying clothes indoors on radiators can increase the risk of exposure to amongst other things Aspergillus – a highly dangerous mould that can be fatal for asthma sufferers and the elderly. In areas where cellulosic materials paper and wood, including drywall become moist and fail to dry within 48 hours, mold mildew can propagate and release allergenic spores into the air.

In many cases, whether materials have failed to dry out several days after the suspected water event, mold growth is suspected within wall cavities even if it is for not immediately visible. Through a mold investigation, which may include destructive inspection, one should be experienced to defining 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 testing and inspections should be carried out by an self-employed grownup investigator to avoid any conflict of interest and to insure accurate results.

There are some varieties of mold that contain toxic compounds mycotoxins. However, exposure to hazardous levels of mycotoxin via inhalation is non possible in most cases, as toxins are introduced by the fungal body and are non at significant levels in the released spores. The primary hazard of mold growth, as it relates to indoor air quality, comes from the allergenic properties of the spore cell wall. More serious than most allergenic properties is the ability of mold to trigger episodes in persons that already have asthma, a serious respiratory disease.

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. Common domination of carbon monoxide are tobacco smoke, space heaters using fossil fuels, defective central heating furnaces and automobile exhaust. By depriving the brain of oxygen, high levels of carbon monoxide can lead to nausea, unconsciousness and death. According to the American Conference of Governmental Industrial Hygienists ACGIH, the time-weighted average TWA limit for carbon monoxide 630–08–0 is 25 ppm.

Volatile organic compounds VOCs are emitted as gases fromsolids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. Concentrations of numerous VOCs are consistently higher indoors up to ten times higher than outdoors. VOCs are emitted by a wide formation of products numbering in the thousands. Examples include: paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials and furnishings, chain 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.

Chlorinated drinking water releases chloroform when hot water is used in the home. Benzene is emitted from fuel stored in attached garages. Overheated cooking oils emit acrolein and formaldehyde. A meta-analysis of 77 surveys of VOCs in homes in the US found the top ten riskiest indoor air VOCs were acrolein, formaldehyde, benzene, hexachlorobutadiene, acetaldehyde, 1,3-butadiene, benzyl chloride, 1,4-dichlorobenzene, carbon tetrachloride, acrylonitrile, and vinyl chloride. These compounds exceeded health specification in most homes.

Organic chemicals are widely used as ingredients in household products. Paints, varnishes, and wax all contain organic solvents, as do many cleaning, disinfecting, cosmetic, degreasing, and hobby products. Fuels are made up of organic chemicals. All of these products can release organic compounds during usage, and, to some degree, when they are stored. Testing emissions from building materials used indoors has become increasingly common for floor coverings, paints, and many other important indoor building materials and finishes.

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. This can calculation in chronic and low-level exposures to VOCs.

Several initiatives envisage 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,Indoor Air Comfort in Europe, as well as California specifics CDPH Section 01350 and several others in the US. These initiatives changed the marketplace where an increasing number of low-emitting products has become available during the last decades.

At least 18 Microbial VOCs MVOCs have been characterised3-methylfuran, 3-octanol, 2-octen-1-ol, 2-nonanone, borneol, geosmin, 1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, and thujopsene. The number one of these compounds is called mushroom alcohol. The last four are products of Stachybotrys chartarum, which has been linked with sick building syndrome.

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 keeps 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 effect has involved outdoor fountains in 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 right normal hot water levels to allow for 120 °F 50 °C at the tap, evaluating facility layout layout, removing faucet aerators, and periodic testing in suspect areas.

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 advanced gene-based analysis of environmental samples. Currently efforts are under way to joining microbial ecologists and indoor air scientists to forge new methods for analysis and to better interpret the results.

"There are approximately ten times as many bacterial cells in the human flora as there are human cells in the body, with large numbers of bacteria on the skin and as gut flora." A large fraction of the bacteria found in indoor air and dust are shed from humans. Among the most important bacteria requested to occur in indoor air are Mycobacterium tuberculosis, Staphylococcus aureus, Streptococcus pneumoniae.

Many common building materials used previously 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 administration program for intact asbestos-containing materials is often recommended instead.

When asbestos-containing fabric 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, in particular the specific form mesothelioma. The risk of lung cancer from inhaling asbestos fibers is significantly greater to smokers, however there is no confirmed joining to harm caused by asbestosis . The symptoms of the disease do not usuallyuntil about 20 to 30 years after the first exposure to asbestos.

]

Carbon dioxide CO₂ is a relatively easy to measure surrogate for indoor pollutants emitted by humans, and correlates with human metabolic activity. Carbon dioxide at levels that are unusually high indoors may cause occupants to grow drowsy, to receive headaches, or to function at lower activity levels. Outdoor CO₂ levels are usually 350–450 ppm whereas the maximum indoor CO₂ level considered acceptable is 1000 ppm. Humans are the leading indoor source of carbon dioxide in most buildings. Indoor CO₂ levels are an indicator of the adequacy of outdoor air ventilation relative to indoor occupant density and metabolic activity.

To eliminate most complaints, the result indoor CO₂ level should be reduced to a difference of no greater than 700 ppm above outdoor levels. The USA National Institute for Occupational Safety and Health NIOSH considers that indoor air concentrations of carbon dioxide that exceed 1,000 ppm are a marker suggesting inadequate ventilation. The UK standards for schools say that carbon dioxide in all teaching and learning spaces, when measured at seated head height and averaged over the whole day should not exceed 1,500 ppm. The whole day talked to normal school hours i.e. 9:00am to 3:30pm and includes unoccupied periods such as lunch breaks. In Hong Kong, the EPD established indoor air quality objectives for house buildings and public places in which a carbon dioxide level below 1,000 ppm is considered to be good. European standards limit carbon dioxide to 3,500 ppm. OSHA limits carbon dioxide concentration in the workplace to 5,000 ppm for prolonged periods, and 35,000 ppm for 15 minutes. These higher limits are concerned with avoiding harm of consciousness fainting, and do not address impaired cognitive performance and energy, which begin to occur at lower concentrations of carbon dioxide. precondition the well established roles of oxygen sensing pathways in cancer and the acidosis freelancer role of carbon dioxide in modulating immune and inflammation linking pathways, it has been suggested that the effects of long-term indoor inspired elevated carbon dioxide levels on the modulation of carcinogenesis be investigated.

Carbon dioxide concentrations increase as a result of human occupancy, but lag in time gradual cumulative occupancy and intake of fresh air. The lower the air exchange rate, the slower the buildup of carbon dioxide to quasi "steady state" concentrations on which the NIOSH and UK direction are based. Therefore, measurements of carbon dioxide for purposes of assessing the adequacy of ventilation need to be made after an extended period ofoccupancy and ventilation – in schools at least 2 hours, and in offices at least 3 hours – for concentrations to be a reasonable indicator of ventilation adequacy. Portable instruments used to measure carbon dioxide should be calibrated frequently, and outdoor measurements used for calculations should be madein time to indoor measurements. Corrections for temperature effects on measurements made outdoors may also be necessary.

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.[]

Ozone is produced by ultraviolet light from the Sun hitting the Earth's atmosphere especially in the ozone layer, lightning,high-voltage electric devices such as air ionizers, and as a by-product of other types of pollution.

Ozone exists in greater concentrations at altitudes commonly flown by passenger jets. Reactions between ozone and onboard substances, including skin oils and cosmetics, can produce toxic chemicals as by-products. Ozone itself is also irritating to lung tissue and harmful to human health. Larger jets have ozone filters to reduce the cabin concentration to safer and more comfortable levels.

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[] as well as ] Ventilation with outdoor air containing elevated ozone concentrations may complicate remediation attempts.

Ozone is on the list of six criteria air pollutant list. The Clean Air Act of 1990 required the United States Environmental protection Agency to set National Ambient Air Quality Standards NAAQS for six common indoor air pollutants harmful to human health. There are also multiple other organizations that have put forth air standards such as Occupational Safety and Health Administration OSHA, National Institute for Occupational Safety and Health NIOSH, and the World Health Organization WHO. The OSHA standard for Ozone concentration within a space is 0.1 ppm. While the NAAQS and the EPA standard for ozone concentration is limited to 0.07 ppm. The type of ozone being regulated is ground-level ozone that is within the breathing range of most building occupants

Atmospheric particulate mater, also known as affect the health of occupants. Authorities have established standards for the maximum concentration of particulates to ensure indoor air quality.