Temporal distribution of fine particulates (PM_2.5, PM₁₀), potentially toxic metals, PAHs and Metal-bound carcinogenic risk in the population of Lucknow City, India

Abstract

Ubiquitous fine particulates can readily be bound to toxic metals and polycyclic aromatic hydrocarbons and are considered to be a great threat to human health. The purpose of this study was to assess the magnitude of air pollution risks to public health by determining four crucial parameters- inhalable particulates, metals in particulates and PAHs which are associated with PM₁₀ in the air environment of Lucknow, India during 2007–09. The values of PM₁₀ and PM_2.5 ranged between 102.3–240.5 and 28.0–196.9 μg/m³ whilst the average PM₁₀ was 1.7 times and PM_2.5 was 1.5 times higher than their respective NAAQS of 100 and 60 μg/m³ respectively. The estimated relative death rate and hospital admissions for each increase in the PM₁₀ levels of 10 μg/m³ ranged from 1.5–8% and from 3.9–8.0% (as per APHEA2 1990) respectively in persons > 65 yrs. Among the locations; AQ_S-1, AQ_S-2, and AQ_S-3 (with diversified activities and heavy traffic) recorded higher concentrations of both the particulate fractions than the AQ_S-4 (residential area with low traffic). The average concentrations of Fe, Pb, Ni, Cu, Cr, Cd in PM₁₀ were 219.4, 40.6, 35.1, 27.3, 22.2 and 16.2 ng/m³ and that in PM_2.5 were 54.3, 33.9, 38.5, 29.4, 8.4, and 1.17 ng/m³ respectively_. Regression analysis revealed that correlation of metals with PM_2.5 was stronger than PM₁₀. The ratio of metals adsorbed on surface of particles (PM_2.5:PM₁₀) reveals that PM_2.5 has more affinity for Ni, Cu and Pb and PM₁₀ for Cd, Fe and Cr. Health risk due to carcinogenic metals bound to respirable particulates was predicted by estimating excess cancer risk (ECR). The highest ECR value was estimated for Cr, 266.70 × 10⁻⁶, which was associated with PM10 and 100.92 × 10⁻⁶ which was associated with PM_2.5, whereas lead has the lowest ECR value. Amongst PAHs, benzo(a)pyrene (51.96±19.71 ng/m³) was maximum in PM₁₀ samples. Maximum concentrations of PM₁₀, PM_2.5, metals and PAHs were detected during winter, and the lowest was during monsoon. The higher prevalence of diseases among the population may be due to high concentration of particulates coated with toxic metals and PAHs present in air environment.

Keywords:

• Fine particulates
• metal
• PAHs
• health risk.