Aromatic hydrocarbons and aldehydes in the atmosphere of Grenoble, France.

Ambient levels and night and day profiles of aromatic hydrocarbons (benzene, toluene, (m+p)xylene, o-xylene and ethyl benzene) and aldehydes (formaldehyde, acetaldehyde, n-butanal, n-pentanal, n-hexanal and benzaldehyde) were measured in Grenoble, France, during a selected week from May, 4, 1995 to May, 11, 1995. Most abundant aromatic hydrocarbons observed were toluene (up to 3.5 ppbv), benzene and (m+p)-xylene (0-3 ppbv). Formaldehyde was the most abundant aldehyde with concentrations ranging from 2 to 18 ppbv followed by acetaldehyde with levels from 2 to 10 ppbv. Gas phase concentrations of four other aldehydes were in the range 0-2 ppbv. Results are discussed with respect to direct emissions and photochemical production. Formaldehyde appears to come mainly from exhaust car emissions but acetaldehyde from other primary sources. (C) 1998 Elsevier Science Ltd. All rights reserved.