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.