Nitrogen dioxide , nitric oxide indirect

The temperature and density structure of the troposphere, along with the concentrations of major constituents, are well documented and altitude profiles have been measured over a wide range of seasons and latitudes for the minor species water, carbon dioxide, and ozone. A few profiles are available for carbon monoxide, nitrous oxide, methane, and molecular hydrogen, while only surface or low-altitude measurements have been made for nitric oxide, nitrogen dioxide, ammonia, sulfur dioxide, hydrogen sulfide, and nonmethane hydrocarbons. No direct measurements of nitric acid and formaldehyde are available, though indirect information does exist. The concentrations of a number of other important species, such as peroxides and oxy and peroxy radicals, have never been determined. Therefore, while considerable information concerning trace constituent concentrations is available, the picture is far from complete. 

Air pollutants can affect plants both directly and indirectly. The principal phytotoxic air pollutants are ozone, nitric oxide, nitrogen dioxide, sulfur dioxide, fluorides, and peroxyacyl nitrate (PAN). Their toxic effects have been demonstrated convincingly through field measure-... 

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