Measurements of formic and acetic acid levels in the vapour phase at Dayalbagh, Agra, India

Acetic and formic acid concentrations were determined in the vapour phase at ground level at Dayalbagh, Agra, during the winter and summer of 1992–1993. Ion chromatography was used to measure the species. Yearly means were 1.7±1.6 ppbv for acetic acid and 1.3±1.4 ppbv for formic acid (N = 137). Average winter mixing ratios (N = 60) for acetic acid and formic acid were 1.8±1.6 and 1.4±1.4 ppbv, respectively, and the corresponding summer levels (N = 77) were 1.3±1.2 and 1.1±1.2 ppbv but seasonal variation was not statistically significant. These concentrations are within the range reported at other sites worldwide. The F/A (formate-to-acetate) ratio showed a diurnal variation with higher averages in the day (1.2) than at night (0.45). With respect to wind direction, the W sector appears to be the cleanest and is associated with the lowest mean concentrations of acetic and formic acids; local sources as well as the ones on a larger scale appear to contribute to the levels recorded in this study.