Characterization and Risk Assessment of PM2.5-Bound Polycyclic Aromatic Hydrocarbons and their Derivatives Emitted from a Typical Pesticide Factory in China.

Polycyclic aromatic hydrocarbons (PAHs) and their derivatives have received extensive attention due to their negative effects on the environment and on human health. However, few studies have performed comprehensive assessments of PAHs emitted from pesticide factories. This study assessed the concentration, composition, and health risk of 52 PM2.5-bound PAHs during the daytime and nighttime in the vicinity of a typical pesticide factory. The total concentration of 52 PAHs (Σ52PAHs) ranged from 53.04 to 663.55 ng/m3. No significant differences were observed between daytime and nighttime PAH concentrations. The average concentrations of twenty-two parent PAHs, seven alkylated PAHs, ten oxygenated PAHs, and twelve nitrated PAHs were 112.55 ± 89.69, 18.05 ± 13.76, 66.13 ± 54.79, and 3.90 ± 2.24 ng/m3, respectively. A higher proportion of high-molecular-weight (4-5 rings) PAHs than low-molecular-weight (2-3 rings) PAHs was observed. This was likely due to the high-temperature combustion of fuels. Analysis of diagnostic ratios indicated that the PAHs were likely derived from coal combustion and mixed sources. The total carcinogenic equivalent toxicity ranged from 15.93 to 181.27 ng/m3. The incremental lifetime cancer risk from inhalation, ingestion, and dermal contact with the PAHs was 2.33 × 10-3 for men and 2.53 × 10-3 for women, and the loss of life expectancy due to the PAHs was 11,915 min (about 0.023 year) for men and 12,952 min (about 0.025 year) for women. These results suggest that long-term exposure to PM2.5 emissions from a pesticide factory has significant adverse effects on health. The study results support implementing the characterization of PAH emissions from pesticide factories and provides a scientific basis for optimizing the living environment around pesticide factories.

Characterization of polycyclic aromatic hydrocarbon (PAHs) source profiles in urban PM2.5 fugitive dust: A large-scale study for 20 Chinese cites.

Polycyclic aromatic hydrocarbons (PAHs) in road dust (RD) and construction dust (CD) in PM2.5 were quantified in the samples collected in 20 Chinese cities. The PAHs profiles in urban PM2.5 fugitive dusts were determined and their potential health risks were evaluated. Seven geographical regions in China were identified as northwest China (NWC), the North China Plain (NCP), northeast China (NEC), central China (CC), south China (SC), southwest China (SWC), and east China (EC). The overall average concentrations of total quantified PAHs (ΣPAHs) were 23.2 ±â€¯18.9 and 22.8 ±â€¯29.6 µg·g-1 in RD and CD of PM2.5, indicating that severe PAHs pollution to urban fugitive dusts in China. The differences of ΣPAHs between RD and CD were minor in northern and central regions of China but much larger in southern and east regions. The Æ©PAHs for RD displayed a pattern of "high in northern and low in southern", and characterized by large abundance of high molecular weights (HMWs) PAHs, indicating that vehicle emission was the predominant pollution origin. Additionally, higher diagnostic ratios of fluoranthene/(fluoranthene + pyrene) in NCP, CC, and SWC suggest critical contributions of biomass burning and coal combustion for RD in these areas. In comparison, gasoline combustion was the major pollution source for CD PAHs in NWC, NCP, NEC, and CC, whereas industrial emissions such as cement production and iron smelting had strong impacts in the heavy industrial regions. The total benzo[a]pyrene (BaP) carcinogenic potency concentrations (BaPTEQ) for RD and CD both showed the lowest in SC (0.05 and 0.07, respectively) and the highest in NCP (10.99 and 7.67, respectively). The highest and lowest incremental life cancer risks (ILCR) were found in NCP and SC, coinciding with the spatial distributions of ambient PAHs levels. The total CD-related cancer risks for adults and children (~10-4) suggest high potential health risks in NCP, SWC, and NWC, whereas the evaluated values in EC and SC indicate virtual safety (≤10-6).

Chemical source profiles of urban fugitive dust PM2.5 samples from 21 cities across China.

Urban fugitive (road and construction) dust PM2.5 samples were collected in 21 cities of seven regions in China. Seven water-soluble ions, eight sub-fractions of carbonaceous components, and 19 elements were determined to investigate the chemical profiles of urban fugitive dust. Among the analyzed chemical compositions and on regional average, the elemental compositions showed the highest proportion (12.5-28.9% in road dust (RD) and 13.1-38.0% in construction dust (CD)), followed by water-soluble ions (5.1-19.0% in RD and 4.2-16.4% in CD) and carbonaceous fractions (5.4-9.6% in RD and 4.9-9.3% in CD). Chemical compositions measured in CD were all slightly lower than those in RD although statistically insignificant (p > 0.05). Soil dust, which was estimated from Fe concentration, was proved to be the biggest contributor to urban fugitive dust PM2.5 mass. While, it showed a higher contribution in Northern China (71.5%) than in Southern China (52.1%). Higher enrichment factors were found for elemental S, Zn and Pb in RD than CD, reflecting stronger anthropogenic sources (i.e. vehicle exhaust) in RD. Low NO3-/SO42- and high SO42-/K+ ratios both indicated that fugitive dust was strongly influenced by stationary sources (e.g. coal combustion), and this influence was especially strong in Northern China. Coefficients of divergence proved that dust profiles within the same region were more similar than across regions, reflecting that urban fugitive dust was influenced more by local sources than long-range transport.

Characterization and cytotoxicity of PAHs in PM2.5 emitted from residential solid fuel burning in the Guanzhong Plain, China.

The emission factors (EFs) of polycyclic aromatic hydrocarbons (PAHs) in PM2.5 were measured from commonly used stoves and fuels in the rural Guanzhong Plain, China. The toxicity of the PM2.5 also was measured using in vitro cellular tests. EFs of PAHs varied from 0.18 mg kg-1 (maize straw charcoal burning in a clean stove) to 83.3 mg kg-1 (maize straw burning in Heated Kang). The two largest influencing factors on PAH EFs were air supply and volatile matter proportion in fuel. Improvements in these two factors could decrease not only EFs of PAHs but also the proportion of 3-ring to 5-ring PAHs. Exposure to PM2.5 extracts caused a concentration-dependent decline in cell viability but an increase in reactive oxygen species (ROS), tumor necrosis factor a (TNF-α) and interleukin 6 (IL-6). PM2.5 emitted from maize burning in Heated Kang showed the highest cytotoxicity, and EFs of ROS and inflammatory factors were the highest as well. In comparison, maize straw charcoal burning in a clean stove showed the lowest cytotoxicity, which indicated a clean stove and fuel treatment were both efficient methods for reducing cytotoxicity of primary PM2.5. The production of these bioreactive factors were highly correlated with 3-ring and 4-ring PAHs. Specifically, pyrene, anthracene and benzo(a)anthracene had the highest correlations with ROS production (R = 0.85, 0.81 and 0.80, respectively). This study shows that all tested stoves emitted PM2.5 that was cytotoxic to human cells; thus, there may be no safe levels of exposure to PM2.5 emissions from cooking and heating stoves using solid fuels. The study may also provide a new approach for evaluating the cytotoxicity of primary emitted PM2.5 from solid fuel burning as well as other PM2.5 sources.

Optical source profiles of brown carbon in size-resolved particulate matter from typical domestic biofuel burning over Guanzhong Plain, China.

In this study, both PM2.5 and size-resolved source samples were collected from a "heated kang" and an advanced stove to investigate the optical properties of brown carbon (BrC). The light-absorption coefficient (babs), the absorption Ångström exponent (AAE), and the mass absorption cross-section (MAC) of both water and methanol-extracted BrC were investigated. The methanol-extracted BrC (BrCmethanol) had higher light absorption than water-extracted BrC (BrCwater). The value of PM2.5 babs of BrCmethanol at 365nm (babs365,methanol) dramatically decreased from 64,669.8Mm-1 for straw burning in the "heated kang" to 1169.2Mm-1 for maize straw briquettes burning in the advanced stove at the same burning rate. The value of PM2.5 MAC for BrCmethanol at 365nm (MAC365,methanol) decreased from 1.8m2g-1 in the "heated kang" to 1.3m2g-1 in the advanced stove. For smoldering burning in the "heated kang", babs365,methanol, MAC365,methanol, and K+ showed a unimodal distribution that peaked at sizes <0.4µm. However, the babs365,methanol and MAC365,methanol size distributions of the briquette burning in the advanced stove showed a bimodal pattern, with a large peak at sizes <0.4µm and a minor peak in the size range of 4.7-5.8µm. The babs365,methanol value for sizes <0.4µm (277.4Mm-1) was only 12.3% compared to those obtained from the "heated kang". The burning rate did not influence the size distribution pattern of either the "heated kang" or the advanced stove. Results from a radiative model show that biomass burning is an important factor for light absorptivity, and the use of an advanced stove can reduce the simple forcing efficiency value by nearly 20% in UV bands compared to the "heated kang". Our results indicate that changing the combustion style from maize straw smoldering to briquette burning in an advanced stove can effectively reduce BrC emissions during heating seasons in rural areas of Guanzhong Plain.