Observations of air quality on the outskirts of an urban agglomeration during the implementation of pollution reduction measures

Abstract Based on observations at Heshan, a boundary area in the city agglomeration of the Pearl River Delta region in China, atmospheric pollutants such as PM 2.5 , O 3 , CO, SO 2 , NO Z , NO 2 and NO were monitored between the 12 th and 29 th November, 2010. Meteorological parameters, including temperature, humidity, dew point, air pressure, ultraviolet light, wind direction, and wind speed were also measured. By combining the meteorological parameters with the atmospheric pollutant data, we performed Positive Matrix Factorization (PMF) and ozone production efficiency (OPE) analysis to objectively understand the interrelations among the pollutants, as well as between the pollutants and the meteorological factors. During the observation period, there were various meteorological changes such as rainfall, cold air transit, and sunshine that created conditions for the formation or dispersal of pollutants. The study period coincided with the 16 th Asian Games, during which time the government adopted strict measures to reduce the discharge of pollutants around the Pearl River Delta area. However, we still observed serious pollution of PM 2.5 and O 3 , of which the highest value of PM 2.5 was 210 μg m −3 and the highest value of O 3 reached 117 ppb. At the same time, the high concentrations of CO, NO, NO 2 , NO Z , and SO 2 could not be cleared away with rainfall in such a short period of time. On the basis of PMF analysis, we found that three factors influence the air quality of this region: local biomass burning, secondary pollutants of regional transport, and high industrial pollutant emissions. According to OPE analysis, the O 3 pollution was mostly found to be VOC–sensitive but occasionally NO X –sensitive for OPE values greater than 10.