Investigation of PM 2.5 chemical composition and associated health risk in residential microenvironments in Mumbai

Abstract

Abstract We breathe in indoor air for 85–90% of our time. PM2.5 is a significant pollutant in indoor air. This study investigates elemental carbon (EC), organic carbon (OC), ions, and elemental composition of PM2.5 in two residential microenvironments (Room 1 and Room 2) and corresponding outdoors. Room 1 had no prominent biomass burning, whereas cooking and smoking were present in Room 2. The average concentration of OC were 19.51 µg/m3, 51.87 µg/m3, and EC were 2.53 µg/m3 and 7.20 µg/m3 in Room 1 and Room 2, respectively. The indoor-to-outdoor ratio (I/O) of EC was 0.58 for Room 1 and 1.01 for Room 2 .100% of EC in Room 1 was coming from outdoor; on the other hand, 41% of EC was indoor-generated in Room 2. Indoor secondary organic carbon (ISOC) was 1.04 times and 1.98 times higher than corresponding outdoor (OSOC) for Room 1 and Room 2, respectively. The I/O ratios of EC1 and EC2 were less than 1 in Room 1. The ratios were closer to 1 in Room 2 because of indoor cooking and smoking. K concentration was higher in Room 2 because of smoking. The hazard risk (HR) and cancer risk (CR) were calculated in all the indoor sites. Though the sites were hazard-free from airborne elements (all HR values < 1), the CR values were > 10− 4 in both the microenvironments from inhalation. Both indoor microenvironments were marginally cancer-risk-prone. This paper has shown that everyday household chores can alter indoor chemistry significantly from outdoor.