Combustion particles emitted during church services: Implications for human respiratory health

Burning candles and incense generate particulate matter (PM) that produces poor indoor air quality and may cause human pulmonary problems. This study physically characterised combustion particles collected in a church during services. In addition, the emissions from five types of candles and two types of incense were investigated using a combustion chamber. The plasmid scission assay was used to determine the oxidative capacities of these church particles. The corresponding risk factor (CRf) was derived from the emission factor (Ef) and the oxidative DNA damage, and used to evaluate the relative respiratory exposure risks. Real-time PM measurements in the church during candle–incense burning services showed that the levels (91.6 μg/m3 for PM10; 38.9 μg/m3 for PM2.5) exceeded the European Union (EU) air quality guidelines. The combustion chamber testing, using the same environmental conditions, showed that the incense Ef for both PM10 (490.6–587.9 mg/g) and PM2.5 (290.1–417.2 mg/g) exceeded that of candles; particularly the PM2.5 emissions. These CRf results suggested that the exposure to significant amounts of incense PM could result in a higher risk of oxidative DNA adducts (27.4–32.8 times) than tobacco PM. The generation and subsequent inhalation of PM during church activities may therefore pose significant risks in terms of respiratory health effects.

► Exposure assessments were performed by measurement of candle–incense PM.
► A combustion chamber was used to measure and collect candle–incense emitted PM.
► Oxidative DNA damage caused by candle–incense PM was determined.
► A quantitative risk indicator was used to assess the respiratory exposure.
► Church-related PM poses a higher respiratory health risk than tobacco smoke.