Investigation of micro-climatic features (vegetation) affecting the indoor air quality in suburb cities of Colombo

Abstract

Considerable number of studies show a favourable impact of vegetation and an adverse impact of synthetic built environment on urban micro-climates. Despite these findings, people eradicate these favourable micro-climatic features for built purposes. In the past few decades suburbs of the Colombo, the capital city of Sri Lanka, was subjected to a rapid development mainly for residential purposes. As a result, paddy fields, marshy lands and large tree canopies have been converted to a built environment with scattered green patches. This study was aimed at determination of the impact of micro-climatic features on air quality and thermal comfort. Air quality investigations were carried out in five residential buildings which were selected based on the surrounding micro-climatic features. Indoor concentrations of CO2, NO2, PM2.5, CO, VOC, temperature, relative humidity and wind speeds were measured during the day time from 9.00 AM to 4.00 PM in each sample building. The results were checked against the air quality standards and an attempt has been made to establish a relationship with micro-climatic features. The results showed that the air quality in suburbs is still in the acceptable range except for peaking of PM2.5 concentration beyond the threshold time to time. Lower levels of temperature and CO2 concentration were observed with good micro-climatic features. Decrease of PM2.5 concentration was also detected with the increase of distance to the main road and vegetation cover. These findings will benefit the township planning in terms of preserving the air quality and thermal comfort levels in suburbs.