Atmospheric Research Center (ARC) has been engaged in monitoring and studying fine particulate matter (PM2.5) of the Pearl River Delta for the past years. The PM2.5 speciation network of four sites (Guangzhou, Nansha, Dongguan and Nanhai) covers areas with different pollution characteristics (urban area, suburban area and area influenced by high density light industries). Since 2008, PM2.5 filter sampling has been conducted following a 1-in-6 day sampling schedule recommended by the United States Environmental Protection Agency. ARC laboratory is equipped with quite a few state-of-the-art analytical instruments for atmospheric PM sample analysis, such as the weighing facility (temperature and RH controlled; a digital microbalance with a sensitivity of ±1 µg), ion chromatography (IC) system, aerosol carbon analyzer, and gas chromatograph/mass spectrometer (GCMS). Detailed standard operating procedures (SOPs) have been prepared for laboratory analysis and data treatment.