Emissions of PAHs from Indoor Crop Residue Burning in a Typical Rural Stove: Emission Factors, Size Distributions, and Gas−Particle Partitioning

Abstract

Indoor combustion of crop residues for cooking or heating is one of the most important emission sources of polycyclic aromatic hydrocarbons (PAHs) in developing countries. However, data on PAH emission factors (EFs) for burning crop residues indoor, particularly those measured in field were scarce, leading to large uncertainties in the emission inventories. In this study, EFs of PAHs for nine commonly used crop residues burnt in a typical Chinese rural cooking stove were measured in simulated kitchen. The measured EFs of total PAHs averaged at 63 ± 37 mg/kg, ranging from 27 to 142 mg/kg, which were higher than those measured in chamber experiments, implying that the laboratory experiment based emission and risk assessment should be carefully reviewed. EFs of gaseous and particulate phase PAHs were 27 ± 13 and 35 ± 23 mg/kg, respectively. Composition profiles and isomer ratios of emitted PAHs were characterized. Stepwise regressions found that modified combustion efficiency and fuel moisture were the most important factors affecting the emissions. 80 ± 6 % of PAHs were associated with PM2.5 and the mass percentage of PAHs in fine particles increased as the molecular weight increased. For freshly emitted PAHs, absorption into organic carbon, rather than adsorption, dominated the gas-particle partitioning.

Occurrence and carcinogenic potential of airborne polycyclic aromatic hydrocarbons in some large-scale enclosed/semi-enclosed vehicle parking areas

“…Similar results were also found for PAHs freshly emitted from wood combustion [45] and indoor crop residue burning [46]. Some reports showed that adsorption on diesel soot (mainly elemental carbon) also plays an important role in partitioning of PAHs in urban atmosphere influenced by vehicular emission [47,48].…”

Household fuel use for cooking and heating in China: Results from the first Chinese Environmental Exposure-Related Human Activity Patterns Survey (CEERHAPS)

“…Also, it is important to note that although our results indicate that the proportion of solid-fuel users decreased from 1991 to 2012, since the overall population in China increased significantly (from 1.16 billion in 1991 to 1.35 billion in 2012), the absolute number of people using solid fuels was still extremely large (Table S2). This suggests that a significant number of people are potentially exposed to harmful pollutants, and consequently at high risk for the development of disease, as inefficient burning of solid fuels often yield a large number of incomplete pollutants [18][19][20].…”

Size distributions of polycyclic aromatic hydrocarbons in urban atmosphere: sorption mechanism and source contributions to respiratory deposition

“…They mainly result from incomplete combustion of carbon-containing materials and can partition between the gas and the particulate phase (Fernán-dez et al, 2002;Hytönen et al, 2009;Shen et al, 2011). This partitioning process strongly depends on particle sizes, PAH species and temperature, and it affects PAH transport, deposition, and degradation as well as health impacts.…”