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In order to study the effects of different atmospheres ( nitrogen and air) and temperature ranges (300 ~ 500 °C, 300 ~ 700 °C and 300 ~ 900 °C ) on the composition and amount of pyrolysis products in paper-making reconstituted tobacco substrates, solid phase microextraction, adsorption-desorption and gas chromatography-mass spectrometry methods were used for analysis. The results showed that under the nitrogen and air atmospheres, the pyrolysis products of substrates at the range of 300 ~ 700 °C and 300 ~ 900 °C obviously increased when compared with those at the range of 300 ~500 °C . A large number of polycyclic aromatic hydrocarbons and olefins were produced in these two temperature ranges. Nicotine was only found in the pyrolysis products of substrates at the range of 300 ~ 500 °C. The contents of furfural and phytadiene were higher at these three temperature ranges. In the same temperature range,under the air atmosphere,the release amount of important cleavage products such as crotonaldehyde, 2-methyl-furan and furfural with relatively low molecular weight was higher than that under nitrogen atmosphere. The relative release of alcohols increased, and the presence of oxygen in air promoted the full combustion of substrates, thereby resulting in the reduction of total pyrolysis products. [ABSTRACT FROM AUTHOR]

Emission factors (EFs) are crucial for establishing emission inventory and subsequent health risk assessment of pollutants. However, the EFs of environmentally persistent free radicals (EPFRs) in PM 2.5 have not been well investigated. We measured EPFRs in PM 2.5 from burning of different solid fuels in a traditional stove widely used in rural China and calculated the EFs of EPFRs (EF EPFRs ). The characteristics of EPFRs varied greatly with PM 2.5 depending on the feedstock, and the EF EPFRs of crop residue, firewood and bitumite was 2.13 ± 1.04, 1.40 ± 0.76 and 1.08 ± 0.39 (10 20 spins·kg -1 ), respectively. The estimated results of EPFRs emission associated with PM 2.5 showed that the crop residue was the main contributor to the top four provinces with high EPFRs emissions in China in 2010. A wide range (0.03-4.89 cig·person -1 ·day -1 ) of equivalent cigarette number converted by inhaling EPFRs in PM 2.5 was observed. Provinces with higher equivalent cigarette number were mainly agricultural provinces, because the rural residents tend to use readily available fuels. Additionally, EPFRs in collected PM 2.5 during 2 - month photoaging were more stable in particles with higher organic carbon contents. Our findings provided a new insight into the risk assessment of PM 2.5 from different sources by taking EPFRs into consideration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)