Abstract: The statistical characteristics of inhalable particles were determined based on mass concentration data of PM₁₀, PM_2.5 and PM₁ observed in the atmospheric boundary layer station of the Chinese Meteorological Administration in Tianjin during September 1 to November 30, 2010. Daily variations of ρ(PM₁₀₎, ρ(PM_2.5) and ρ(PM₁) were analyzed separately in typical synoptic conditions combined with meteorological data during the same period. Relationships were determined between mass concentration of different sized particulate matter and wind speed and direction. The results show that the daily average of ρ(PM₁₀₎ was above the second standard of the national air quality standards for more than half of the days during the observation period. ρ(PM_2.5) was above the US EPA 1997 standard for 63 days, accounting for 76.8% of the time. Diurnal variations of ρ(PM₁₀₎, ρ(PM_2.5) and ρ(PM₁) were obviously different among different weather conditions: largest in the dense fog or blowing sand/dust condition, and lowest in the precipitation condition. Coarse particles PM_2.5-10 (diameter 2.5-10 μm) and PM₁ were the main components of the inhalable particles in Tianjin. The mass concentrations of PM_2.5-10, PM_1-2.5 and PM₁ mainly accumulated when the wind speed was less than 3 m/s and the wind direction was 225°-280° and 70°-110°. When the wind speed exceeded 3 m/s, ρ(PM_2.5-10) and ρ(PM_1-2.5) increased to some extent. The air pollutants varied greatly during the week, but no “weekend effect” was observed.