Photooxidants
Photooxidants are reactive oxidants that arise under the influence of (sun) light. They can trigger a variety of chemical reactions in the environment , which contribute to air pollution .
In the air, nitrogen oxides can react with hydrocarbons and oxygen under the influence of intense solar radiation to form so-called photo-oxidants. These include ozone , peroxyacetyl nitrate (PAN), nitric acid and other reaction products that have oxidizing properties.
It is believed that ozone plays a central role in the development of forest damage. The World Health Organization (WHO) recommends an ozone concentration of less than 60 μg / m 3 during the growing season. Lung dysfunction and inflammation of the airways due to ozone are also suspected. If the ozone concentration exceeds a value of around 300 μg / m 3 air, visibility becomes cloudy, known as photochemical smog ( Los Angeles smog ).
On the other hand, photooxidants, especially the OH radical, are responsible for the rapid degradation ( photodegradation ) of many air pollutants such as B. CO in the atmosphere, according to:
- O 3 + hν → O 2 + O *
- O * + H 2 O → 2 OH
- CO + OH → CO 2 + H
- H + O 2 → HO 2
- HO 2 + O 3 → OH + 2 O 2
See also
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- ↑ Studies on the effect of ozone on lung dysfunction ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. (PDF; 131 kB).
- ^ Andreas Heintz, Guido A. Reinhardt: Chemistry of Photooxidants from Chemistry and Environment (Google Books) .
