Seasonal variation of carbonyl compound concentrations in urban area of Hong Kong

Ambient levels of carbonyls were determined at the roadside urban station of the Hong Kong Polytechnic University (HKPU) campus and it was the first systematic investigation of carbonyls at a roadside station in Hong Kong. A 12-month monitoring program for carbonyl compounds was carried out during April 1999–April 2000. Ten carbonyl compounds were quantified in this study. The most abundant carbonyl compound was formaldehyde, followed by acetaldehyde and acetone. The 24-hour average concentrations of formaldehyde and acetaldehyde were 4.13 and 2.01 μg/m3. Most carbonyls have higher average concentrations at Tsuen Wan (TW) Toxic Air Pollutants (TAPs) monitoring station during summertime due to the addition of industrial emission from the nearby industrial area. Characterization of the roadside concentrations of carbonyl compounds was compared with the long-term ambient air quality monitoring data acquired by Hong Kong Environmental Protection Department (HKEPD) under TAP Monitoring Programme. Seasonal variations and winter/summer ratios at the monitoring station are discussed. Correlations and statistical analysis of the carbonyls were performed and comparison of carbonyl compounds concentrations at roadside and TAP monitoring stations determined.