Indoor air quality of non-residential urban buildings in Delhi, India

Nearly 30% of total population and over 2 million students of Delhi spent above 1/3rd of their daily time in different office buildings and educational institutions of Delhi, of which the ambient air quality is reportedly worst in the globe. However, studies on indoor air quality of non-residential buildings are scarce in India. Present study was conducted in two office buildings and one educational building in Delhi during pre-monsoon. CO2, PM2.5 and VOCs were measured inside each building at every 5 min interval between 9:30 AM and 5:30 PM for 5 days every week. The average CO2 concentration in both office buildings (1513 ppm and 1338 ppm) was recorded much higher than the ASHRAE standard. Ductless air-conditioning system couple with poor air-circulation and active air-filtration could be attributed to significantly higher concentration of PM2.5 in one of the office buildings (43.8 μg m−3). However, there was significant variation in the concentration of different pollutants at different locations in a building. Among different non-residential buildings, significantly lower concentration of all pollutants was recorded in the educational building (CO2: 672 ppm; PM2.5: 22.8 μg m−3 and VOC: 0.08 ppm). Total hazard ratio analysis ranks one of the office buildings as most hazardous to workers health compared to others.