Variation characteristics of PM_(2.5) concentration and its relationship with PM_(10) and TSP in Beijing

Based on two years simultaneous one-week integrated sampling, in two downtown/residential sampling sites in Beijing, PM2.5 concentration and its temporal variation feature in ambient air were analyzed. Weekly PM2.5 average concentrations ranged from 37 to 346mg/m3 and the annual average was near or over the second class annual average standard of PM10. PM2.5 concentration possessed markedly the variation feature with highest in winter and lowest in summer. Weekly and seasonal variations of PM2.5 concentrations were similar between the two sampling sites. Both PM2.5 to PM10 and PM2.5 to TSP ratios were highest in winter and lowest in spring, reflecting heating combustion sources contributed more to fine particles, while dust weather did more to coarse particles. Annul averages of PM2.5/PM10 and PM2.5/TSP were 55% and 29% respectively.