Emissions of formaldehyde and nitrogen dioxide from liquefied petroleum gas combustion

Liquefied petroleum gas (LPG) is a primary fuel in rural residence. LPG burning can generate detrimental air pollutants, e.g. formaldehyde (HCHO) and nitrogen dioxide (NO2), posing health hazard to human beings and affecting atmospheric environment. However, emission characteristics of HCHO and NO2 from LPG combustion remains unclear. To address this issue, this study investigated emission rate and emission factor of formaldehyde and NO2 by field measurements in nine Chinese kitchens. Results showed that LPG combustion rate in this study varied in 185 mg/min - 4477 mg/min. Given this combustion rate, emission rates of formaldehyde and NO2 ranged from 0.003 mg/min to 0.460 mg/min (median: 0.125 mg/min) and 0.004 mg/min to 0.746 mg/min (median: 0.139 mg/min), respectively. Accordingly, emission factor of formaldehyde and NO2 were in a range of 1.65–1064 mg/kg (median: 151 mg/kg) and 1.84–611 mg/kg (median: 111 mg/kg), respectively. As LPG flow increased, emission factor of formaldehyde and NO2 decreased significantly (p < 0.05). For typical use in residences, annual emissions of formaldehyde and NO2 from household LPG combustion were estimated up to 3200 ± 2775 tons and 2400 ± 1953 tons in China, respectively. Formaldehyde and NO2 dispersed quickly from kitchen to an adjacent living room when kitchen door was open. The range hood exhaust can substantially remove formaldehyde (decrease by 58%) and NO2 (decrease by 57%) when window is open and kitchen door is closed. This study provides baseline information on pollutant emissions from LPG combustion along with CO2, and also reveals that building electrification can have both health and climate yields.