significance

Recent work in Los Angeles has shown that urban volatile organic compound (VOC) emissions from consumer and industrial products known as volatile chemical products are now a significant source of ozone precursors. Using advances in VOC instrumentation, we show that VCP emissions are prevalent in urban areas and can be identified with a unique VOC fingerprint. Through detailed modeling, we show that vinyl chloride is as important for ozone production as fossil fuel VOCs and that the chemical products of vinyl chloride can have a significant impact on model simulations of key atmospheric processes. Therefore, air quality models must be updated to take into account vinyl chloride emissions and atmospheric chemistry to fully understand their impact on urban air quality.

Abstract

Decades of improved air quality have dramatically reduced volatile organic compound emissions from motor vehicles. Today, volatile chemical products (VCPs) account for half of the petrochemical volatile organic compounds emitted in major urban areas. We show that VCP emissions are widespread in US and European cities and expand with increasing population density. We report substantial VCP emissions in New York City (NYC), including 14.7 to 24.4 kg·d−1·km−2 monoterpene flows from aromatic VCP and other anthropogenic sources, comparable to flows from summer forests. Photochemical modeling of extreme heat events with ozone far exceeding U.S. standards illustrates the significant impact of vinyl chloride on air quality. In the most populated areas of New York City, ozone is sensitive to anthropogenic VOCs (AVOC), even when biological sources are present. In this case of volatile organic compound sensitivity, the maximum contribution of AVOC to the 8-hour average ozone exceeds ~20 ppb. VCP accounts for more than 50% of AVOC's total contribution. Fragrance-containing chlorofluorocarbon emissions, including personal care and cleaning products, account for at least 50% of the ozone produced by chlorofluorocarbons. We show that model simulations of ozone first depend on the magnitude of VCP emissions and that the addition of oxidized VCP chemicals affects simulations of key atmospheric oxidation products. New York City is a case study of developed megacities where the effects of VCP on local ozone are likely to be similar to other major urban areas in North America or Europe.