Abstract
Mass concentrations of size-resolved PM were monitored by a cascade impactor (PCIS) during two winter and one summer seasons in a small village situated in West Bohemia. Continuous concentrations of PM2.5 were measured in parallel by a photometer DustTrak.
Basic meteorological parameters (temperature, relative humidity, wind velocity, wind direction, precipitation and sun radiation) were monitored as well. Presence of persons and their activities in the house were recorded in a diary.
The average PM10 concentrations in the village were higher than average PM10 concentration in the nearby town. The summer average PM10 concentrations in the village were lower than those in the town (15.5 μg/m3 vs 17.4 μg/m3) while the winter PM10 concentrations in the village were significantly higher (31.1 μg/m3 vs 24.3 μg/m3).
The average indoor concentrations (PM10 and PM2.5) were lower in the summer (9.6 μg/m3 vs 8.3 μg/m3) than in the winter season (24.0 μg/m3 vs 20.7 μg/m3). The presence of people indoors resulted in indoor PM2.5 concentrations higher than outdoors (I/O ratio 1.41).
In the absence of people the PM2.5 concentrations as well as the I/O ratio (0.55) dropped down. Presence of people caused increase in concentrations of quasi-ultrafine particles (< 0.25 µm) presumably due to heating and coarse particles (10 - 2.5 µm) due to resuspension.
Regarding ambient PM levels the highest PM10 and PM2.5 concentrations were recorded during low temperature and low wind velocity periods. The PM10 concentrations in the village highly correlated with those from the nearest town during the winter season (0.92).
The correlation dropped to 0.67 during the summer. Analysis of wind direction showed that the town emissions affected the village levels only exceptionally.
We conclude that the major source of pollution in the village is not the transport from the nearest town but local heating of houses burning wood and coal in stoves.