Spatial and seasonal variation of air quality in different microenvironments of a technical university in India

Abstract

The present study aims to assess spatial and seasonal variations of indoor air quality (IAQ) among ten different indoor microenvironments of a technical university in India. Particulate matters (PM 10 and PM 2.5 ), total volatile organic compounds (TVOCs), carbon dioxide (CO 2 ), and indoor environmental quality (IEQ) indicators (i.e. temperature, relative humidity, and ventilation) were monitored during monsoon, winter and summer seasons from August 2018 to June 2019. The occupants’ perception about IAQ of studied microenvironments was analysed from 137 valid responses. The IAQ was found varying significantly (P < 0.05) among the studied microenvironments. The highest concentrations for indoor PM 10 , PM 2.5 and CO 2 were found in lecture halls with concentration exceeding the recommended guidelines values and standards; whereas the higher TVOC levels with exceeding the threshold limit were recorded in the laboratories. Further, the ventilation rate in the studied lecture halls and offices were found below the recommended ASHRAE values. Indoor concentrations of PM 10 , PM 2.5 , and TVOC showed strong seasonal variation (P < 0.05). PM 10 and PM 2.5 concentrations were found higher in the winter season, ranging from 1.8 μg/m 3 to 159.7 μg/m 3 and from 18.2 μg/m 3 to 108 μg/m 3 , respectively. The indoor microenvironments having natural ventilation with open windows had shown higher seasonal variation compared to an air-conditioned microenvironment. Indoor to outdoor (I/O) ratios of PM 2.5 , TVOC and CO 2 concentrations were found to be greater than 1. Indoor activities, ventilation and occupancy, were responsible for seasonal and spatial variability among indoor microenvironments. • IAQ varied significantly among microenvironments and across the seasons. • Indoor to outdoor ratio was greater than 1 for PM 2.5 , TVOC and CO 2. • Naturally ventilated microenvironments had shown higher seasonal variations. • PM 10 , PM 2.5 , and CO 2 exceeded the recommended health standards.