Category:Indoor air pollutants

Trichloroethylene

Definition

Trichloroethylene (TCE) is a widely used industrial solvent. It is a volatile, colourless liquid with a sweet odour (similar to chloroform). It is mainly used for steam degreasing and cold cleaning of manufactured metal parts (80-95% of consumption). Other applications include industrial dry cleaning, printing, printing ink production, extraction processes, paint production and textile printing.

Predominant sources of emissions

Contaminated water can be a source of indoor exposure because it can volatilise rapidly from surface water through showering or the use of washing machines and dishwashers, for example. Contaminated soil can also contribute to TCE concentrations in ambient air through vapour intrusion (when TCE in soil gas enters dwellings through cracks in foundations). Dermal exposure can contribute to total exposure, especially through the use of detergent products or showering. In addition, the use of products where TCE is used as a solvent can led to high concentrations in indoor air.

Legislation and intervals

According to the World Health Organization, since there is sufficient evidence that TCE is a genotoxic carcinogen, all indoor exposures are considered relevant and no threshold can be determined.

Tetrachloroethylene

Definition

Tetrachloroethylene (PCE) is a colourless, readily volatile liquid with an ether-like odour. The main industrial applications of PCE are as a dry-cleaning agent, degreaser for fabricated metal parts, and industrial solvent. Other applications include textile finishing, production of printing inks, and formulation of adhesives.

Predominant sources of emissions

There are no known natural sources of PCE. Concerning indoor sources: -Contaminated drinking water can be a source of indoor exposure to PCE. - Dry-cleaning workers have become sources of PCE in the home by exhaling it. - Dry-cleaned laundry is also a possible source of PCE. - Soil contamination with PCE has led to concentrations of these chemicals in indoor air as they evaporate and can leach through indoor air.

Legislation and intervals

According to World Health Organization, the limit value for tetrachloroethylene is 0.25 mg/m3 on an annual average.

Polycyclic aromatic hydrocarbons

Definition

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants formed in the combustion process of carbonaceous materials at high temperature. They are a large group of organic compounds with two or more fused aromatic rings. Low molecular weight PAHs (two and three rings) are found in the atmosphere predominantly in the vapour phase, while multi-ring PAHs (five or more rings) are largely particle bound and are considered very dangerous to human health.

Predominant sources of emissions

Benzo(a)pyrene is often used as a marker for total exposure to carcinogenic PAHs, as its contribution to the total carcinogenic potential is high. Indoor air is polluted by PAHs, which come not only from infiltration or intrusion of outdoor air, but also from indoor emission sources such as smoking, cooking, domestic heating with fuel cookers and open fireplaces, as well as emissions from incense and candles.

Legislation and intervals

According to DIRECTIVE 2004/107/EC of the European Parliament and of the Council of 15 December 2004 relating to arsenic, cadmium, mercury, nickel and polycyclic aromatic hydrocarbons in ambient air: The limit value for Benzo(a)pyrene is 1 ng/m3 on an annual average. However, according to World Health Organization, no threshold can be determined and all indoor exposures are considered health relevant.

Naphthalene

Definition

Naphthalene occurs naturally in fossil fuels such as oil and coal, and is produced when burning wood or tobacco. It is also the most volatile polycyclic aromatic hydrocarbon (PAH) with a gas phase share of 90-100%.

Predominant sources of emissions

Limited information is available on indoor air concentrations of naphthalene and exposure levels. Common indoor sources of naphthalene are unvented paraffin stoves and tobacco smoke. Used in the household as a moth repellent.

Legislation and intervals

According to World Health Organization: The limit value for Naphthalene is 0.01 mg/m3 on an annual average.

PM10

Definition

PM10 particles are those with diameters of less than 10 micrometres. PM10 is largely composed of primary particles emitted directly into the atmosphere by both natural phenomena and the human activities, such as combustion processes in kitchens, use of wood-burning cookers, tobacco, electronic cigarettes, etc.

Legislation and intervals

According to World Health Organization: The limit value for PM10 is 45 μg/m3 for 24 hours and 15 μg/m3 on an annual average. According to DIRECTIVE 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe: The limit value for PM10 is 50 μg/m3 for 24 hours average and 40 μg/m3 on an annual average.

PM2.5

Definition

PM2.5 particles are those with diameters of less than 2.5 micrometres*. They are therefore a subset of PM10 particles and more harmful than PM10, as they can reach further into the lungs and can be more toxic. PM2.5 particles are usually composed mainly of secondary particles formed in the atmosphere from some of the gaseous precursors.

Legislation and intervals

According to World Health Organization: The limit value for PM2.5 is 15 μg/m3 for 24 hours and 5 μg/m3 on an annual average. According to DIRECTIVE 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe: The limit value for PM2.5 is 20 μg/m3 on an annual average.

PM0.1

Definition

The so-called ultrafine particles (UFP), which are smaller than 0.1 micrometre, are considered to be among the most dangerous pollutants, as due to their small size they can even reach the bloodstream and thus affect various organs, as well as the central nervous system and the reproductive system, among others.

Legislation and intervals

The legislated particle sizes are PM2.5 and PM10; although UFPs are among the most dangerous airborne pollutants, there are no regulatory standards to control UFP emissions.

CO

Definition

Carbon monoxide (CO) is a colourless, odourless gas emitted as a result of incomplete combustion of fossil fuels and biofuels.

Predominant sources of emissions

In general, any fuel containing carbon (gas, oil, coal, wood...) that is burned without sufficient oxygen to form CO2 is a potential source of CO. Carbon monoxide is produced indoors by combustion sources (cooking and heating) and is also introduced through infiltration of carbon monoxide from outdoor air into the indoor environment. Clogged fireplaces, heaters without properly functioning safety devices and tobacco smoke are the most important sources of carbon monoxide exposure.

Legislation and intervals

According to World Health Organization: The limit value for CO is 100 mg/m3 for 15 minutes average, 35 mg/m3 for 1 hour average, 10 mg/m3 for 8 hours average and 7 mg/m3 for 24 hours average. According to DIRECTIVE 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe: The limit value for CO is 10 mg/m3 for 8 hours average.

NO2

There are seven nitrogen oxides that can be found in ambient air. However, nitric oxide (NO) and nitrogen dioxide (NO2) are the two main nitrogen oxides associated with combustion sources.

Definition

Nitrogen dioxide (NO2) is a reactive gas that is formed mainly by the oxidation of NO. It is involved in harmful reactions such as those leading to tropospheric ozone or nitric acid, and is therefore a pollutant in its own right as well as a precursor to other pollutants. Under ambient conditions, both outdoors and indoors, nitrogen dioxide exists in gaseous form.

Predominant sources of emissions

The main indoor sources of this pollutant are fuel-burning cookers (wood, paraffin, natural gas, propane, etc.), fuel-burning heating systems (wood, oil, natural gas, etc.) and tobacco use.

Legislation and intervals

According to both the World Health Organization and DIRECTIVE 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe: The limit value for NO2 is 200 μg/m3 for 1 hour average and 40 μg/m3 on an annual average.

Radon

Definition

Radon gas is a major source of naturally occurring ionising radiation and a major contributor to the ionising radiation doses received by the population. Prolonged exposure to radon may increase the risk of lung cancer. The unit of measurement is the Becquerel per cubic metre (Bq-m-3).

Predominant sources of emissions

It is produced by the natural radioactive decay of uranium in soils and rocks, which penetrates into interior spaces driven by pressure, as the air inside an enclosed space is usually warmer, therefore at lower pressure than the gas in the underlying soil.

Legislation and intervals

According to World Health Organization: The limit value for Radon is 100 Bq/m3 (If such a level cannot be achieved in the current country-specific circumstances, the chosen reference level should in any case not exceed 300 Bq/m3) on an annual average. According to Council Directive 2013/59/Euratom of 5 December 2013 laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation, and repealing Directives 89/618/Euratom, 90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122/Euratom: The limit value for Radon is 300 Bq/m3 on an annual average.

O3

Definition

Ozone (O3) is a secondary pollutant formed from a complex series of chemical reactions of primary precursor pollutants, mainly NOx and VOCs, in the presence of solar radiation. Ozone has a positive effect in the stratosphere, where it forms the so-called ozone layer, as it protects against ultraviolet radiation. However, in the troposphere it becomes a pollutant that acts as a powerful and aggressive oxidising agent.

Predominant sources of emissions

Ozone is a pollutant of concern in outdoor air, as the primary pollutants with which it reacts mainly come from road traffic, but ozone is also generated indoors by the use of electrical appliances such as photocopiers, laser printers, ionising air cleaners or disinfection devices.

Legislation and intervals

According to World Health Organization: The limit value for O3 is 100 μg/m3 for 8 hours average. According to DIRECTIVE 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe: The limit value for O3 is 120 μg/m3 for 8 hours average.