Investigation of formaldehyde and other carbonyls in a small urban atmosphere using passive samplers. A comprehensive data analysis

Abstract Carbonyls are important pollutants in urban atmospheres not only for their contribution to the formation of oxidants such as ozone and peroxyacetyl nitrate (PAN) but also for their adverse effects on human health. Formaldehyde is toxic and carcinogenic to humans. Seasonal variations of carbonyl compounds were investigated at two sampling sites in the atmosphere of Ciudad Real, a small city in central southern Spain. Air samples were collected for one year from February 2015 to February 2016 using passive samplers. Between the eleven carbonyls identified formaldehyde, acetone and acetaldehyde were the most abundant carbonyls accounting for 34 %, 20 % and 14 %, respectively of the total concentration of carbonyls. The total concentration of carbonyls detected ranged from 2.35 to 22.46 µg m-3 with an average of 6.89 ± 4.7 µg m-3. A comprehensive statistical analysis has been carried out in order to determine the differences in the carbonyl concentrations between both sampling points and the main emission sources taking into account the sample size. The seasonal trend observed for formaldehyde, acetaldehyde and acetone implies the presence of significant photochemical reactions in summer to produce carbonyls. The C1/C2 ratios, Spearmans correlation coefficients, the propene-equivalent and the total ozone formation potentials were also calculated in this study.