Emissions of soot, PAHs, ultrafine particles, NO_x, and other health relevant compounds from stressed burning of candles in indoor air

摘要

Burning candles release a variety of pollutants to indoor air, some of which are of concernfor human health. We studied emissions of particles and gases from the stressedburning of five types of pillar candles with different wax and wick compositions. Thestressed burning was introduced by controlled fluctuating air velocities in a 21.6 m~3laboratory chamber. The aerosol physicochemical properties were measured bothin well-mixedchamber air and directly above the candle flame with online and offlinetechniques. All candles showed different emission profiles over time with highrepeatability among replicates. The particle mass emissions from stressed burningfor all candle types were dominated by soot (black carbon; BC). The wax and wickcomposition strongly influenced emissions of BC, PM_(2.5), and particle-phasepolycyclicaromatic hydrocarbons (PAHs), and to lower degree ultrafine particles, inorganic andorganic carbon fraction of PM, but did not influence NO_x, formaldehyde, and gas-phasePAHs. Measurements directly above the flame showed empirical evidence ofshort-livedstrong emission peaks of soot particles. The results show the importanceof including the entire burn time of candles in exposure assessments, as their emissionscan vary strongly over time. Preventing stressed burning of candles can reduceexposure to pollutants in indoor air.