Characteristics of Particulate Matter during Haze and Fog (Pollution) Episodes over Northeast China, Autumn 2013

ABSTRACT

Mass concentrations of particulate matter (PM), including PM_1.0, PM_2.5 and PM₁₀, were measured from October 13^th to November 30^th 2013 at eight sites in Northeast China to evaluate their variations during pollution periods. Five major pollution periods were identified during the autumn of 2013. The maximum daily average PM_2.5 concentrations were 437 ± 85 µg/m³ and 322 ± 50 µg/m³ in Harbin and Shenyang, respectively. The minimum was 75 ± 28 µg/m³ in Dandong. The presence of finer particles was significantly related to visibility degradation during pollution periods. Wind speeds had a negative correlation with PM concentrations, while high relative humidity (RH) favored the formation of haze in Northeast China.

Visibility on non-hazy days was approximately 2.5–3.0 times greater than that on hazy days. During hazy days, the PM_1.0:PM_2.5 ratios were 0.89 ± 0.04, 0.85 ± 0.04 and 0.91 ± 0.04 at Anshan, Shenyang and Dandong, respectively. These results show that PM_1.0 was the dominant particle pollutant in Northeast China during periods of pollution. High RH and low wind speeds during hazy days may favor the accumulation of atmospheric pollutants. The results of this study provide useful information toward recognizing air pollution episode characteristics in Northeast China.