Characteristics of emissions of air pollutants from mosquito coils and candles burning in a large environmental chamber

The objective of this study was to characterize the emissions of air pollutants from mosquito coils and candles burning in a large environmental test chamber. The target pollutants included particulate matters (PM10, PM2.5), carbon monoxide (CO), nitrogen oxides (NOx), methane (CH4), non-methane hydrocarbons (NMHC), volatile organic compounds (VOCs) and carbonyl compounds. The average PM10concentrations for all tested mosquito coils exceeded Excellent and Good Classes objectives specified by Indoor Air Quality Objectives for Office Buildings and Public Places (IAQO) [HKEPD, 2003. Guidance Notes for the Management of Indoor Air Quality in Offices and Public Places. Indoor Air Quality Management Group, The Government of the Hong Kong Special Administrative Region]. The emission factors (mg g-1mosquito coil) of mosquito coils combustion were: PM2.5, 20.3-47.8; PM10, 15.9-50.8; CO, 74.6-89.1; NO, 0.1-0.5; NO2, n.d.-0.1; NOx, 0.1-0.5; CH4, n.d.-4.7; NMHC, 0.1-5.7. Formaldehyde and acetaldehyde were the most abundant carbonyls species in the coil smoke. The average concentrations of formaldehyde and benzene of all tested mosquito coils exceeded Good Class of IAQO. Nitrogen oxides were the most abundant gas pollutants relating to candle burning among all target air pollutants. The candle made of gel (CAN 4) would emit more air pollutants than the paraffin candles (CAN 1, 2 and 3) and beeswax candle (CAN 5). Among five candles tested, CAN 5, the one made of beeswax, generated relatively smaller amount of air pollutants. It was noted that the concentrations of most VOCs from candles combustion were below the detection limit.