Measurements of PM10 and PM2.5 in urban area of Nanjing, China and the assessment of pulmonary deposition of particle mass

Measurement of PM10 and PM2.5 was carried out at six sites of Nanjing, China in the period of February-May 2001. The pH and conductivity of water-soluble matter of PM10 and PM2.5 were determined, and the samples were analyzed for total carbon (TC), organic carbon (OC) and inorganic carbon (IC) of the water-soluble fraction. The distribution of aerosol mass concentration in size was also measured at one site SB by a nine-stage impactor followed to assess the pulmonary deposition of particles in different tracts of the human respiratory system. Compared with National Ambient Air Quality Standard (NAAQS) of the USA, the level of PM 10 and PM2.5 in Nanjing was much higher. Especially for site SY, the average particle mass concentrations (774.5 μg/m³ for PM10 and 481.4 μg/m³ for PM2.5) were more than five times the NAAQS standard. At site SB aerosol mass distribution in size had shown the similar characteristics with accumulation (D_p < 1 μm) and coarse (D_p > 1 μm) modes. More than 70% of total suspended particles is of a size that they are deposited in the respiratory tract below trachea, whereas about 22% of the mass is respirable and will reach the alveoli. Water-soluble fractions of PM 10 and PM2.5 in Nanjing are acidic, and the pH of PM2.5 is lower than that of PM10. OC makes up the majority of TC and accounts for 3-14% of mass concentration of PM10 and/or PM2.5, while IC only accounts for 0.1-0.5% of PM10 and/or PM2.5 mass.