Indoor and outdoor levels of particulate matter concentration in a district of Tokyo in the late 1980s

Abstract

We conducted the measurements of the concentrations of particulate matter (PM; PM_2.5, PM_10-2.5 and PM₁₀) at a district in Tokyo late 1980s. The environmental measurements were conducted four times indoors in 200 households and two times both indoors and outdoors in 100 households. We obtained the following results.
PM concentrations were higher in winter than in summer. Outdoor PM_2.5 and PM₁₀ concentrations were higher in roadside area than backyard but not for PM_10-2.5. PM_2.5 concentrations in the smokers' houses were significantly higher than those in the non-smokers' houses. PM_2.5 concentrations increased according to the number of cigarettes smoked and its magnitude was large in winter because of the small air-exchange. PM_2.5 concentrations in houses using un-ventilated stoves were significantly higher than thosein houses using ventilated stoves. PM_10-2.5 concentrations showed the same results but the significant difference was found only in February 1987 where ambient temperature was the lowest. I/O ratios (indoor concentration/ outdoor concentration) were lower in winter than in summer for PM_2.5, PM_10-2.5 and PM₁₀ except for PM_2.5 and PM₁₀ in smokers' houses. Indoor PM_10-2.5 concentrations were significantly lower than outdoors. The correlation coefficients between the indoor and outdoor concentrations were large in summer for all PM. The outdoor PM_2.5/ PM₁₀ratios were larger in winter than in summer and were smaller than those indoors. Indoor PM_2.5/ PM₁₀ ratios ranged 60 to 80% and showed a tendency to be larger in winter.
In this study we clarified the indoor and outdoor concentration levels of PM_2.5, PM_10-2.5 and PM₁₀ in different seasons in Tokyo late 1980s and we discussed some factors which regulate the indoor-outdoor relationships of PM. Further we determined the relationship between PM2.5 and PM₁₀.