||California Univ., Riverside. Statewide Air Pollution Research Center. ;California State Air Resources Board, Sacramento. ;South Coast Air Quality Management District, El Monte, CA. ;Environmental Protection Agency, Washington, DC.;Coordinating Research Council, Inc., Atlanta, GA.
The effects of 36 representative volatile organic compounds (VOCs) and CO on ozone formation, NO oxidation, and OH radical levels were measured in a series of environmental chamber experiments representing conditions where VOCs have the greatest effect on photochemical ozone formation. The experiments consisted of repeated 6-hour indoor chamber irradiations of a simplified mixture of ozone precursors with NOx in excess, alternating with runs with varying amounts of a test VOC added. The VOCs studied included representative alkanes, alkenes, aromatic hydrocarbons, aldehydes, alcohols, ethers, alcohol ethers, and siloxanes. CO, Acetone and 2-chloromethyl-3-chloropropene were also studied. Reactions of formaldehyde, acetone, the methylbenzenes and the alkenes had the largest positive effects on OH radical levels, and because of this they caused the most NO oxidation and ozone formation per molecule reacted. Reactions of the siloxanes and the C(6+) n-alkanes had the most inhibiting effects on radicals, causing them to inhibit NO oxidation and ozone formation under the conditions of these experiments. The other compounds had smaller and usually negative effects on OH radicals, and had moderate but positive effects on ozone formed and NO oxidized. Information was also obtained on amounts of NO oxidation caused directly by the reactions of the added VOCs or their products.