Exposure of churchgoers to airborne particles.

Particle mass and number measurements in a church indicate significant increases of indoor particle concentrations during the burning of incense. Generally, varying concentration regimes can be attributed to different "modes of indoor activity" and emission sources. While periods of candle burning are negligible concerning particle concentrations, increases by a factor of 6.9 and 9.1 during incense burning were observed for PM10 and PM1, respectively. At maximum, indoor PM10 shows an 8.1-fold increase in comparison to outdoor measurements. The increase of particles < 2 microm is significantly enhanced in comparison to larger particles. Due to a particle decay rate of 0.9 h(-1) post-service concentrations are elevated for a time span of approximately 24 h above indoor background concentrations.