Comparisons of ambient air particulates concentrations (TSP, PM2.5) and dry depositions during smog and non-smog periods at Luliao, Shalu District sampling site

Abstract

The concentrations of ambient total suspended particulates (TSP) and PM2.5, and the dry depositions at a sample site at Luliao Junior High School (Luliao) in central Taiwan were measured during smog and non-smog days between December 2017 and July 2018. The results are compared to those obtained during non-smog periods in the years 2015–2017. The mean TSP and PM2.5 concentrations and dry deposition flux were 72.41 ± 26.40, 41.88 ± 23.51 μg/m3, and 797.57 ± 731.46 μg/m2 min, respectively, on the smog days. The mean TSP and PM2.5 concentrations and dry deposition flux on the non-smog days were 56.39 ± 18.08, 34.81 ± 12.59 μg/m3 and 468.93 ± 600.57 μg/m2 min, respectively. The mean TSP concentration in the smog period was 28% greater than that in the non-smog period, and the mean PM2.5 concentration was 20% higher. The mean dry deposition flux in the smog period was 70% higher than that in the non-smog period at Luliao. The PM2.5 concentrations exceeded the standards set by the Taiwan EPA (35 μg/m3 daily, and 15 μg/m3 annually). Therefore, the TSP and PM2.5 concentrations and dry deposition must be reduced in central Taiwan on smog days. In addition, atmospheric TSP and PM2.5 concentrations at various sampling sites were compared, and those herein were not higher than those measured in other countries. Finally, apart from the local traffic emissions, during smog periods, the other pollution source originated from the transportation process of traffic pollutants emitted in the northwest side of Taiwan.