Dynamic interaction of trace gases (VOCs, ozone, and NOx) in the rural atmosphere of sub-tropical India

Abstract

The atmospheric chemistry and health implications of pollutants are important scientific concerns in the rural atmosphere. The current study investigates the estimation of seasonal and diurnal variability of VOCs, ozone, and NOx in the rural area located in a tropical region of India during the year 2013–2014. Results showed that most of the targeted VOCs were higher in winter followed by summer and autumn. The diurnal variability of aromatic hydrocarbons showed similar pattern with different amplitudes as maxima and minima during morning (07:00–10:00 h) or evening (16:00–19:00 h) and daytime (10:00–16:00 h), respectively. The sum of aromatic VOCs are found to be in the range from 27.3 to 87.9 μg/m3. In addition to this, O3 and NOx were observed as 45.04 ± 15.19 μg/m3 and 12.41 ± 3.49 μg/m3, respectively, during the observation period. The estimated VOC/NOx ratios (ranged from 3.4 to 3.7) indicated that the selected rural area was VOC limited in terms of ozone sensitivity. The sources of the VOCs have been explained by characteristic ratios, correlation, and principal component analysis. Further, ozone-forming potential (OFP) of the targeted aromatic VOCs has been evaluated using maximum incremental reactivity which suggested toluene (benzene) contributed the largest (lowest) in the ozone formation. Exposure assessment in terms of lifetime cancer and non-cancer risks lies within the acceptable range of USEPA guidelines.