Molds and other allergens

These biological agents can arise from a number of media, but there are two common classes: (a) moisture induces the growth of mold colonies and (b) natural substances released into the air, such as animal dander and plant pollen. Moisture buildup inside buildings can arise from water penetrating compromised areas of the building envelope or skin, from airtightness, from condensation due to inadequate ventilation, or from soil moisture penetrating a portion of the building. In areas where cellulosic materials (paper and wood, including drywall) become wet and do not dry within 48 hours, mold can spread and release allergenic spores into the air.

In many cases, if materials have failed to dry several days after the suspected event, mold growth is suspected within wall cavities, 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 mold is visible and indoor air quality may have been compromised, mold removal may be necessary. Mold testing and inspections must be performed by an independent investigator to avoid any conflict of interest and ensure accurate results.

There are some varieties of fungi that contain toxic compounds (mycotoxins). However, exposure to dangerous levels of mycotoxins through inhalation is not possible in most cases, since the toxins are produced by the fungal body and are not at significant levels in the spores released. The primary danger of mold growth, as it relates to indoor air quality, comes from the allergenic properties of the cell wall of the spores. More serious than the more serious properties Allergenicity is the ability of mold to cause episodes in people who already have asthma, a serious respiratory disease.

Mold is always associated with humidity,[5]​ and its growth can be inhibited by keeping humidity levels below 50%. Moisture problems that cause mold growth can be direct, such as water leaks, and/or indirect, such as condensation due to humidity levels.

carbon monoxide

One of the most toxic air pollutants is carbon monoxide (CO), a colorless, odorless gas that is a byproduct of the incomplete combustion of fossil fuels. Common sources of carbon monoxide are: tobacco smoke, heaters that use fossil fuels, defective central heating furnaces, instantaneous water heaters (Argentina: calefones, Mexico: calorones de paso) and automobile exhausts. Improvements in indoor CO levels are systematically improving the increasing enforcement of an anti-smoking law. By depriving the brain of oxygen, high levels of carbon monoxide can cause nausea, unconsciousness and death. According to the American Conference of Governmental Industrial Hygienists (ACGIH), the time-weighted concentration (TWA) limit for carbon monoxide (630-08-0) is 25 ppm.

Volatile organic compounds

Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which can have adverse short- and long-term health effects. Many VOC concentrations are consistently higher indoors (up to ten times higher) than outdoors. They are issued for a wide range of products that number in the thousands. Examples include: paints and lacquers, paint strippers, cleaning products, pesticides, building and furniture materials, office equipment such as copiers and printers, correction fluid and carbonless paper, graphics and craft materials such as glues and adhesives, permanent markers and photographic solutions.[6]​.

Organic chemicals are widely used as ingredients in household products. Paints, varnishes, and waxes 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 use, and, to some extent, when stored. Testing emissions of construction materials used indoors has become increasingly common for floor coverings, paints and many other important construction materials and interior finishes.[7]​.

Several initiatives are planned to reduce indoor air pollution by limiting VOC emissions from products. There are regulations in France and in Germany, and numerous voluntary eco-labels and rating systems containing low VOC emissions criteria such as EMICODE, M1 cleaning products,[8]​ Blue Angel[9]​ and Indoor Air Comfort[10]​ in Europe, as well as the California Standard Section 01350 CDPH[11]​ and several others in the US. These initiatives changed the market in which an increasing number of low-emission products have become available over the last decades.

At least 18 microbial volatile organic compounds (MVOCs) have been characterized[12][13] including 1-octen-3-ol, 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 first of these compounds is called mushroom alcohol. The last four are a product of Stachybotrys chartarum, which has been linked to sick building syndrome.[12]​.

Legionella

Legionellosis or Legionnaires' disease is caused by a bacteria called Legionella that grows best in slow-moving or even warm water. The main route of exposure is through the creation of an aerosol effect, usually from evaporative cooling towers or sprinklers. A common source of Legionella in commercial buildings are "cooling towers" in refrigeration systems, which often release water in an aerosol that can enter the respiratory tract through ventilation ducts. Outbreaks in medical centers and nursing homes, where immunocompromised and immuno-weakened patients, are the most common cases of legionellosis. Healthy people require strong exposure to acquiring the infection.

Testing for Legionella typically involves collecting water samples and surface swabs from evaporative cooling basins, showers, faucets/faucets, and other places where hot water accumulates. The samples are then cultured and colony forming units (cfu) of Legionella are quantified as cfu/liter.

Legionella is a Gram-negative, bacillus-shaped bacteria. The bacteria forms a coating that is resistant to chemical and antimicrobial treatments, including chlorine. Remediation of Legionella outbreaks in commercial buildings varies, but generally includes drowning them with water vapor (160°F, 70°C), sterilizing standing water in evaporative cooling basins, replacing showerheads, and in some cases flushing heavy metal salts. Preventive measures include adjusting normal hot water levels to allow 120°F at the faucet, evaluating the facility's layout design, removing faucet aerators, and periodically testing suspected areas.

Other bacteria

The role of microbes in the indoor environment is increasingly studied using modern genetics-based analysis of environmental samples. Efforts are currently underway to link microbial ecologists and indoor air scientists to forge new methods for analysis and to better interpret results.[14]​.

asbestos fibers

The US Federal Government and some States have established standards for acceptable levels of asbestos fibers in indoor air. Many common building materials used before 1975 contain asbestos, such as some tiles, roof slabs, pipe wrap, caulk, and other insulating materials. Normally significant releases of asbestos fibers will not occur unless the building materials are disturbed, such as by cutting, sanding, drilling or remodeling construction. There are strict rules applicable in particular to schools.

Inhalation of asbestos fibers over longer exposure times is associated with a higher incidence of lung cancer, particularly the specific form mesothelioma.

Asbestos is found in older homes and buildings, but is most dangerous in schools and industrial settings. They were once widely used in roof tiles, fireproofing, heating systems and floor and roof tiles in old buildings. When asbestos-containing material is damaged or disintegrates, microscopic fibers are dispersed into the air. The risk of lung cancer from inhaling asbestos fibers is also higher for smokers. Symptoms of the disease generally do not appear until about 20 to 30 years after first exposure to asbestos. Removing asbestos-containing materials is not always optimal, because the fibers can become airborne during the removal process. A management program for intact asbestos-containing materials is often recommended instead.

carbon dioxide

Carbon dioxide (CO) is a surrogate for indoor pollutants emitted by humans and correlates with human metabolic activity. Carbon dioxide at unusually high levels indoors can cause occupants to become drowsy, have headaches, or function at lower activity levels. Humans are the main indoor source of carbon dioxide. Indoor levels are an indicator of the adequacy of outdoor air ventilation in relation to indoor occupancy density and metabolic activity. To remove most of the total carbon dioxide must be reduced to less than 600 ppm above outdoor levels. NIOSH considers indoor air concentrations of carbon dioxide greater than 1,000 ppm to be an indicator suggesting inadequate ventilation. ASHRAE") recommends that carbon dioxide levels do not exceed 700 ppm outdoors above ambient levels.[15] UK standards for schools say that carbon dioxide in all teaching and learning spaces, when measured at the head height of a seated person and averaged over the entire day should not exceed 1,500 ppm. The entire day refers to normal school hours (i.e. 9:00 a.m. to 15:30) and includes unoccupied periods, such as lunchtime. European standards limit carbon dioxide to 3,500 ppm. OSHA supports workplace carbon dioxide concentration limits of 5,000 ppm for long periods and 35,000 ppm for 15 minutes.

ozone

Ozone is produced by ultraviolet light from the sun when it hits the Earth's atmosphere (especially the ozone layer), rays, certain electrical devices (for example: air ionizer, and others.

Ozone exists in higher concentrations at high altitudes typically flown by airliners. Reactions between ozone and substances on board, including skin oils and cosmetics, can produce toxic chemicals as byproducts. Ozone itself is also irritating to lung tissue and harmful to human health. Large jets have ozone filters to reduce cabin concentration to safer and more comfortable levels.[16]​.

Outdoor air for ventilation may have enough ozone to react with common indoor pollutants, as well as skin oils and other common indoor air or surface chemicals. Special concern is warranted when using "green" cleaning products based on citrus or terpene extracts as these chemicals react very quickly with ozone to form toxic and irritating chemicals, as well as atmospheric particulate matter and ultrafine particles. Ventilation with outside air containing high concentrations of ozone can complicate remediation attempts [17]​.

Molds and other allergens

These biological agents can arise from a number of media, but there are two common classes: (a) moisture induces the growth of mold colonies and (b) natural substances released into the air, such as animal dander and plant pollen. Moisture buildup inside buildings can arise from water penetrating compromised areas of the building envelope or skin, from airtightness, from condensation due to inadequate ventilation, or from soil moisture penetrating a portion of the building. In areas where cellulosic materials (paper and wood, including drywall) become wet and do not dry within 48 hours, mold can spread and release allergenic spores into the air.

In many cases, if materials have failed to dry several days after the suspected event, mold growth is suspected within wall cavities, 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 mold is visible and indoor air quality may have been compromised, mold removal may be necessary. Mold testing and inspections must be performed by an independent investigator to avoid any conflict of interest and ensure accurate results.

There are some varieties of fungi that contain toxic compounds (mycotoxins). However, exposure to dangerous levels of mycotoxins through inhalation is not possible in most cases, since the toxins are produced by the fungal body and are not at significant levels in the spores released. The primary danger of mold growth, as it relates to indoor air quality, comes from the allergenic properties of the cell wall of the spores. More serious than the more serious properties Allergenicity is the ability of mold to cause episodes in people who already have asthma, a serious respiratory disease.

Mold is always associated with humidity,[5]​ and its growth can be inhibited by keeping humidity levels below 50%. Moisture problems that cause mold growth can be direct, such as water leaks, and/or indirect, such as condensation due to humidity levels.

carbon monoxide

One of the most toxic air pollutants is carbon monoxide (CO), a colorless, odorless gas that is a byproduct of the incomplete combustion of fossil fuels. Common sources of carbon monoxide are: tobacco smoke, heaters that use fossil fuels, defective central heating furnaces, instantaneous water heaters (Argentina: calefones, Mexico: calorones de paso) and automobile exhausts. Improvements in indoor CO levels are systematically improving the increasing enforcement of an anti-smoking law. By depriving the brain of oxygen, high levels of carbon monoxide can cause nausea, unconsciousness and death. According to the American Conference of Governmental Industrial Hygienists (ACGIH), the time-weighted concentration (TWA) limit for carbon monoxide (630-08-0) is 25 ppm.

Volatile organic compounds

Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which can have adverse short- and long-term health effects. Many VOC concentrations are consistently higher indoors (up to ten times higher) than outdoors. They are issued for a wide range of products that number in the thousands. Examples include: paints and lacquers, paint strippers, cleaning products, pesticides, building and furniture materials, office equipment such as copiers and printers, correction fluid and carbonless paper, graphics and craft materials such as glues and adhesives, permanent markers and photographic solutions.[6]​.

Organic chemicals are widely used as ingredients in household products. Paints, varnishes, and waxes 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 use, and, to some extent, when stored. Testing emissions of construction materials used indoors has become increasingly common for floor coverings, paints and many other important construction materials and interior finishes.[7]​.

Several initiatives are planned to reduce indoor air pollution by limiting VOC emissions from products. There are regulations in France and in Germany, and numerous voluntary eco-labels and rating systems containing low VOC emissions criteria such as EMICODE, M1 cleaning products,[8]​ Blue Angel[9]​ and Indoor Air Comfort[10]​ in Europe, as well as the California Standard Section 01350 CDPH[11]​ and several others in the US. These initiatives changed the market in which an increasing number of low-emission products have become available over the last decades.

At least 18 microbial volatile organic compounds (MVOCs) have been characterized[12][13] including 1-octen-3-ol, 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 first of these compounds is called mushroom alcohol. The last four are a product of Stachybotrys chartarum, which has been linked to sick building syndrome.[12]​.

Legionella

Legionellosis or Legionnaires' disease is caused by a bacteria called Legionella that grows best in slow-moving or even warm water. The main route of exposure is through the creation of an aerosol effect, usually from evaporative cooling towers or sprinklers. A common source of Legionella in commercial buildings are "cooling towers" in refrigeration systems, which often release water in an aerosol that can enter the respiratory tract through ventilation ducts. Outbreaks in medical centers and nursing homes, where immunocompromised and immuno-weakened patients, are the most common cases of legionellosis. Healthy people require strong exposure to acquiring the infection.

Testing for Legionella typically involves collecting water samples and surface swabs from evaporative cooling basins, showers, faucets/faucets, and other places where hot water accumulates. The samples are then cultured and colony forming units (cfu) of Legionella are quantified as cfu/liter.

Legionella is a Gram-negative, bacillus-shaped bacteria. The bacteria forms a coating that is resistant to chemical and antimicrobial treatments, including chlorine. Remediation of Legionella outbreaks in commercial buildings varies, but generally includes drowning them with water vapor (160°F, 70°C), sterilizing standing water in evaporative cooling basins, replacing showerheads, and in some cases flushing heavy metal salts. Preventive measures include adjusting normal hot water levels to allow 120°F at the faucet, evaluating the facility's layout design, removing faucet aerators, and periodically testing suspected areas.

Other bacteria

The role of microbes in the indoor environment is increasingly studied using modern genetics-based analysis of environmental samples. Efforts are currently underway to link microbial ecologists and indoor air scientists to forge new methods for analysis and to better interpret results.[14]​.

asbestos fibers

The US Federal Government and some States have established standards for acceptable levels of asbestos fibers in indoor air. Many common building materials used before 1975 contain asbestos, such as some tiles, roof slabs, pipe wrap, caulk, and other insulating materials. Normally significant releases of asbestos fibers will not occur unless the building materials are disturbed, such as by cutting, sanding, drilling or remodeling construction. There are strict rules applicable in particular to schools.

Inhalation of asbestos fibers over longer exposure times is associated with a higher incidence of lung cancer, particularly the specific form mesothelioma.

Asbestos is found in older homes and buildings, but is most dangerous in schools and industrial settings. They were once widely used in roof tiles, fireproofing, heating systems and floor and roof tiles in old buildings. When asbestos-containing material is damaged or disintegrates, microscopic fibers are dispersed into the air. The risk of lung cancer from inhaling asbestos fibers is also higher for smokers. Symptoms of the disease generally do not appear until about 20 to 30 years after first exposure to asbestos. Removing asbestos-containing materials is not always optimal, because the fibers can become airborne during the removal process. A management program for intact asbestos-containing materials is often recommended instead.

carbon dioxide

Carbon dioxide (CO) is a surrogate for indoor pollutants emitted by humans and correlates with human metabolic activity. Carbon dioxide at unusually high levels indoors can cause occupants to become drowsy, have headaches, or function at lower activity levels. Humans are the main indoor source of carbon dioxide. Indoor levels are an indicator of the adequacy of outdoor air ventilation in relation to indoor occupancy density and metabolic activity. To remove most of the total carbon dioxide must be reduced to less than 600 ppm above outdoor levels. NIOSH considers indoor air concentrations of carbon dioxide greater than 1,000 ppm to be an indicator suggesting inadequate ventilation. ASHRAE") recommends that carbon dioxide levels do not exceed 700 ppm outdoors above ambient levels.[15] UK standards for schools say that carbon dioxide in all teaching and learning spaces, when measured at the head height of a seated person and averaged over the entire day should not exceed 1,500 ppm. The entire day refers to normal school hours (i.e. 9:00 a.m. to 15:30) and includes unoccupied periods, such as lunchtime. European standards limit carbon dioxide to 3,500 ppm. OSHA supports workplace carbon dioxide concentration limits of 5,000 ppm for long periods and 35,000 ppm for 15 minutes.

ozone

Ozone is produced by ultraviolet light from the sun when it hits the Earth's atmosphere (especially the ozone layer), rays, certain electrical devices (for example: air ionizer, and others.

Ozone exists in higher concentrations at high altitudes typically flown by airliners. Reactions between ozone and substances on board, including skin oils and cosmetics, can produce toxic chemicals as byproducts. Ozone itself is also irritating to lung tissue and harmful to human health. Large jets have ozone filters to reduce cabin concentration to safer and more comfortable levels.[16]​.

Outdoor air for ventilation may have enough ozone to react with common indoor pollutants, as well as skin oils and other common indoor air or surface chemicals. Special concern is warranted when using "green" cleaning products based on citrus or terpene extracts as these chemicals react very quickly with ozone to form toxic and irritating chemicals, as well as atmospheric particulate matter and ultrafine particles. Ventilation with outside air containing high concentrations of ozone can complicate remediation attempts [17]​.