Characteristics of particles and black carbon emitted by combustion of incenses, candles and anti-mosquito products

Indoor combustion sources are of great concern when accurate evaluations of the overall human exposure to particles have to be provided. Even if cooking activity was claimed to be the most emitting source in indoor environments, other indoor activities involving incense, candle and anti-mosquito product combustions can produce high particle concentrations. To this purpose, studies evaluating PM fraction emission rates from such indoor activities were performed, even if there is still a lack of understanding in terms of particle number and carbonaceous amount (black carbon, BC) carried by particles themselves. The aim of the present study was to characterize the particle emission due to the combustion processes of incenses, candles and anti-mosquito products. Emission factors in terms of number, surface area and PM fraction concentrations were evaluated through a condensation particle counter, a scanning mobility particle sizer, and an aerodynamic particle sizer. Moreover, BC emission factors were measured through an aethalometer. Particlesʹ BC content distribution was also measured proposing an experimental method made up of a particle size classification device connected to an aethalometer. Emission factors due to incenses and anti-mosquito products were higher than 1014 part h−1 and 48 mg h−1 in terms of number and PM10 concentrations, respectively. Differently, PM fraction emissions from candle burning were well below 1 mg h−1. Nonetheless, BC emission rate and distribution measurements showed that candle flaming combustion produces mainly carbonaceous particles (BC/PM10 ratio higher than 80%). Differently, smoldering combustion processes, like incense and anti-mosquito product combustions, showed a negligible amount of BC.