METROLOGICAL CHANGES IN AMBIENT AIR QUALITY OF RARE AND DENSE AREA IN VARANASI (U.P.)

Abstract

The study assessed ambient and indoor air quality at different roadside and residential locations categorized according to traffic density, housing type, and pollution intensity. The monitored pollutants included carbon oxides (COx), sulfur dioxide (SO₂), nitrogen oxides (NOx), and suspended particulate matter (SPM). The findings revealed significant seasonal and spatial variations in pollutant concentrations, with winter months generally exhibiting the highest levels and monsoon months the lowest. At the roadside locations, S1 rare area (Lanka and Bhojubeer) and S2 dense area (Godauliya and Lahurabeer), pollutant concentrations were strongly influenced by vehicular traffic and local environmental conditions. Roadside area (S2) recorded considerably higher concentrations of COx, NOx, SO₂, and SPM than the relatively less congested S1 location. SPM emerged as the dominant pollutant at both sites, frequently reaching very high levels during winter and post-monsoon periods. Reduced atmospheric dispersion, increased vehicular emissions, road dust resuspension, and combustion activities contributed to elevated pollution during these months. In contrast, rainfall and improved ventilation during the monsoon season significantly lowered pollutant concentrations. Indoor air quality investigations were conducted in both low-category and advanced-category houses located in narrow lanes and roadside environments. Results showed that indoor pollutant concentrations closely reflected outdoor pollution conditions, indicating a strong influence of ambient air on indoor environments. Houses situated in highly polluted areas exhibited elevated levels of COx, NOx, SO₂, and SPM throughout the year. Among all indoor environments, low-category houses located in narrow lanes generally recorded the highest pollutant concentrations. Kitchens consistently showed slightly higher concentrations of gaseous pollutants compared to living rooms, highlighting the impact of cooking-related emissions. However, living rooms often displayed elevated particulate matter levels due to infiltration of outdoor pollutants. Advanced-category houses exhibited lower pollutant concentrations than low-category houses, suggesting that improved building design, better ventilation systems, and superior construction materials can reduce indoor exposure to air pollutants. Roadside residences experienced greater indoor pollution than houses located in relatively sheltered narrow-lane environments. The influence of continuous vehicular emissions was particularly evident in elevated concentrations of COx and SPM. Advanced-category houses situated near busy roads also recorded significant pollutant loads despite their improved housing conditions, indicating that proximity to traffic sources remains a major determinant of indoor air quality.