Measurements of the products of atmospheric photochemical reactions in laboratory studies and in ambient air-relationships between ozone and other products

• Published in: Atmospheric environment 1983, Vol.17 (12), p.2383-2427
• Main Author: Altshuller, A.P.
• Format: Article
• Language: English
• ISSN: 0004-6981; 1352-2310
• DOI: 10.1016/0004-6981(83)90066-5

Many inorganic and organic gaseous and aerosol products including but not limited to aldehydes and ketones, CO, formic acid, peroxyacyl nitrates (PANs), nitric acid and other nitrates, sulfates and organic particles are formed in the atmosphere from atmospheric photochemical reactions. The types of products identified, relationships of products to reactants from smog chamber studies, and ambient air concentrations and distributions are considered in this review. Because O 3 is a key product which is widely measured, it is of considerable interest to determine whether the atmospheric distribution of the other products are strongly related to that of O 3. Most of the same products observed in laboratory studies are present at significant concentrations in the atmosphere. Concentrations of these products usually are at their highest levels in the South Coast Air Basin of California. However, the concentrations of products at other urban locations in the United States do overlap those at locations within the South Coast Air Basin. Peroxyacetyl nitrate (PAN) has been measured in London and Tokyo at concentrations in the same range as in cities within the United States. At nonurban sites the concentrations of the products measured are significantly lower than in urban locations. In clean maritime air the concentrations of several products have been reported to be between 1 and 10% of the concentrations in urban areas. None of the other products are present individually at concentrations approaching that of O 3. In combination, the concentration of other products, even excluding NO 2, in some urban locations can approach and sometimes exceed the concentrations of O 3, especially on a 24-h average basis. The substantial ambient air concentration levels of combinations of products other than O 3 and NO 2 are of possible concern from the air quality viewpoint. The ambient air measurements indicate that O 3 may serve directionally, but cannot be expected to serve quantitatively as an surrogate for the other products. The laboratory studies relating the yields of O 3 and other products to initial hydrocarbon (HC) and NO 2 concentration and HC composition indicate that the variations in other products do not closely match those of O 3.