The chemical composition and sources of PM2.5 during the 2009 Chinese New Year's holiday in Shanghai

► PM2.5 during the Chinese New Year's holiday could give baseline information on the air quality in China. ► Comparison of source contributions under two significantly different conditions was made. ► Vehicle emissions should be the main source of n-alkanes and EC in urban Shanghai. ► Environmental impact and composition of fine particles from fireworks were estimated.