Humidity plays an important role in the PM2.5 pollution in Beijing

2015 
Abstract Heavily-polluted PM 2.5 (fine particulate matter) episodes frequently impacting Beijing, especially during winter, have become a substantial concern. We found that during winter, the daily variation of PM 2.5 in Beijing tracked the pattern of relative humidity (RH). With the increase of PM 2.5 (or RH), water-soluble components (especially inorganic ions) became more abundant, and the water-soluble organic carbon to organic carbon ratios increased. The nitrate to sulfate ratios also exhibited dependence on RH, and were higher than those measured about a decade ago, consistent with the increasing trend of nitrogen oxides emissions. Surprisingly, the ratios of water-insoluble organic carbon to elemental carbon showed significant increase at high RH levels, presumably indicating the formation of secondary organic aerosol that is not soluble in water. In addition, humid winters were occasionally identified during 1996–2013 which are expected to be favorable for the formation of air pollution episodes with high PM 2.5 concentrations.
    • Correction
    • Source
    • Cite
    • Save
    • Machine Reading By IdeaReader
    43
    References
    107
    Citations
    NaN
    KQI
    []