A comparison of PM<sub>2.5</sub>-bound polycyclic aromatic hydrocarbons in summer Beijing (China) and Delhi (India)

Abstract

Abstract. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in air, soil, and water and are known to have harmful effects on human health and the environment. The diurnal and nocturnal variations of 17 PAHs in ambient particle-bound PAHs were measured in urban Beijing (China) and Delhi (India) during the summer season using gas-chromatography–quadrupole time-of-flight mass spectrometry (GC-Q-TOF-MS). The mean concentration of particles less than 2.5 µm (PM2.5) observed in Delhi was 3.6 times higher than in Beijing during the measurement period in both the daytime and night-time. In Beijing, the mean concentration of the sum of the 17 PAHs (∑17 PAHs) was 8.2 ± 5.1 ng m−3 in daytime, with the highest contribution from indeno[1,2,3-cd]pyrene (12 %), while at night-time the total PAHs was 7.2 ± 2.0 ng m−3, with the largest contribution from benzo[b]fluoranthene (14 %). In Delhi, the mean ∑17 PAHs was 13.6 ± 5.9 ng m−3 in daytime and 22.7 ± 9.4 ng m−3 at night-time, with the largest contribution from indeno[1,2,3-cd]pyrene in both the day (17 %) and night (20 %). Elevated mean concentrations of total PAHs in Delhi observed at night were attributed to emissions from vehicles and biomass burning and to meteorological conditions leading to their accumulation from a stable and low atmospheric boundary layer. Local emission sources were typically identified as the major contributors to total measured PAHs in both cities. Major emission sources were characterized based on the contribution from each class of PAHs, with the four-, five- and six-ring PAHs accounting ∼ 95 % of the total PM2.5-bound PAHs mass in both locations. The high contribution of five-ring PAHs to total PAH concentration in summer Beijing and Delhi suggests a high contribution from petroleum combustion. In Delhi, a high contribution from six-ring PAHs was observed at night, suggesting a potential emission source from the combustion of fuel and oil in power generators, widely used in Delhi. The lifetime excess lung cancer risk (LECR) was calculated for Beijing and Delhi, with the highest estimated risk attributed to Delhi (LECR = 155 per million people), which is 2.2 times higher than the Beijing risk assessment value (LECR = 70 per million people). Finally, we have assessed the emission control policies in each city and identified those major sectors that could be subject to mitigation measures.

Characteristics and health risks of personal exposure to particle‐bound PAHs for Hong Kong adult residents: From ambient pollution to indoor exposure

“…As shown in Figure 4, the distributions of modeled ∑15PAHs ( r s = 0.98; p < 0.001), cPAHs ( r s = 0.94; p < 0.001), and BaPeq‐ cPAHs concentration (0.09 ± 0.05 ng/m 3 ) agreed well with measured residential indoor exposures. From this study conducted in Hong Kong, average BaPeq concentrations in ambient and indoor settings were comparable or higher than those in Los Angeles, California (0.07 ng/m 3 ), Houston, Texas (0.03 ng/m 3 ) 21 ; Grenoble, France (0.07 ng/m 3 ), but significantly lower than those in Chinese cities (e.g., BaPeq ‐cPAHs : 1.47 ng/m 3 , BaPeq ‐15PAHs : 2.3 ng/m 3 in Beijing) 19,61 . Carcinogenic PAHs and BaPeq‐ cPAHs exposure concentrations in some residential indoor Hong Kong locations were higher than those of ambient concentrations, demonstrating the potential risk of indoor pollution to human health.…”

“…From this study conducted in Hong Kong, average BaPeq concentrations in ambient and indoor settings were comparable or higher than those in Los Angeles, California (0.07 ng/m 3 ), Houston, Texas (0.03 ng/m 3 ) 21 ; Grenoble, France (0.07 ng/m 3 ), but significantly lower than those in Chinese cities (e.g., BaPeq -cPAHs : 1.47 ng/m 3 , BaPeq -15PAHs : 2.3 ng/m 3 in Beijing). 19,61 Carcinogenic PAHs and BaPeq-cPAHs exposure concentrations in some residential indoor Hong Kong locations were higher than those of ambient concentrations, demonstrating the potential risk of indoor pollution to human health. Other studies revealed similar findings; for instance, Wang et al 62 (2020) reported higher BaPeq concentrations indoors (e.g., dormitory, office, and laboratory) than the ambient air in Wuhan, China.…”

“…These results were consistent with previous findings, 19 providing evidence that BaPeq-cPAHs is a suitable proxy for exposure to individual carcinogenic PAHs. Looking toward reducing exposures, Elzein et al 61 (2020) suggested focusing on mitigating carcinogenic PAHs emissions (e.g., BaP, DBA, BbF, BkF, and IcdP) to reduce the adverse effects of exposure to ambient PAHs in Beijing, something that is also relevant to Hong Kong. toxicity in residential indoor and airway inflammation in adult participants were observed.…”

Atmospheric conditions and composition that influence PM&lt;sub&gt;2.5&lt;/sub&gt; oxidative potential in Beijing, China

“…Partial least squares regression (PLSR) is a supervised regression extension of PCA, which models the variation in the data which is associated with a predefined sample classification (Eriksson et al, 2013). PLSR models were constructed for each individual OP assay and season to examine the most specific markers associated with seasonal assay response.…”

Emissions of non-methane volatile organic compounds from combustion of domestic fuels in Delhi, India

“…However, approximately 60 % of total NMVOC emissions from India in 2010 were estimated to be due to solid-fuel combustion (Sharma et al, 2015). Other studies have also suggested that burning may lead to enhanced concentrations of pollutants such as polycyclic aromatic hydrocarbons in Delhi (Elzein et al, 2020). A need has therefore been identified to measure local source profiles to allow for evaluation with activity data to better understand the impact of unaccounted and unregulated local sources (Pant and Harrison, 2012).…”