ANALYSIS OF THE RELATIONSHIP OF URBAN VEGETATION COVER WITH AIR QUALITY, ITS EXPOSURE AND HEALTH IMPACTS IN DHAKA CITY

Abstract

The research quantifies the relationship of vegetation cover with air quality, its exposure dose and health impacts. The main focus of the study is to develop and analyze the correlation between Normalized Difference Vegetation Index (NDVI) and Air Quality Index (AQI), between NDVI and relative risks of Acute Lower Respiratory Infection (ALRI), Ischemic Heart Disease (IHD), Chronic obstructive pulmonary disease (COPD) and Lung cancer and assess the Average Daily Dose (ADD) of exposure of criteria air pollutants in Dhaka city to find the requirement of uniformly distributed vegetation density that will keep the air quality of Dhaka in safe levels and reduce the risks of health impacts to a negligible level. The research was conducted by analyzing the air quality of Dhaka for the previous years (2016-2020), monitoring air quality of Dhaka at 11 locations, analyzing the spatial distribution of NDVI, criteria air pollutant concentrations and AQI of the study area, relative risk assessment of health impacts using AirQ+ software and exposure dose assessment of Dhaka. The air quality of the monitoring locations was measured using HAZSCANNER HIM-6000. Spatial distribution maps of NDVI, criteria pollutants (PM2.5, PM10, CO, NO2 and SO2), Air Quality Index (AQI) and ADD of exposure were developed using ArcMap. The correlations between the required parameters were presented through graphical representation. From the result, it was concluded that the air quality of Dhaka is more polluted during the winter (dry) season compared to the monsoon (wet) season. The results show that a uniformly distributed vegetation density of 10% or more and 39.7% or more are required in Dhaka city during the monsoon and winter respectively to keep the AQI levels safe under USEPA guidelines. Achieving a relative risk of 1 i.e.; negligible health impacts upon long-term exposure to air pollutants requires a uniformly distributed vegetation density of around 20% or more, during the monsoon season. Dense vegetation is required for such conditions during winter.