Nitrogen oxides (NOx ≡ NO + NO2) are important atmospheric constituents affecting the tropospheric chemistry and climate.They are emitted both from anthropogenic and from natural (soil,lightning,biomass burning,etc.) sources,and China has become a major region of increasing importance for anthropogenic sources.In a series of studies,we use vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) retrieved from satellite remote sensing to estimate anthropogenic and natural emissions of NOx over China.We separate anthropogenic emissions from lightning and soil sources over East China for 2006 by exploiting their different seasonality.We evaluate variations in anthropogenic emissions at different time scales in response to the economic development of China,from the general growth in recent years to the economic downturn during late 2008 – mid 2009 to the holiday associated with the Chinese New Year.By examining trends of NOx emissions,measurements of particulate matter (PM) pollution,and coupled model simulations,we find the rapidly growing NOx emissions to be a key driver of recently deteriorating PM pollution over East China.