Chemical characteristics and oxidative potential of indoor and outdoor PM2.5 in densely populated urban slums

Abhay Anand; Suman Yadav; Harish C Phuleria

doi:10.1016/j.envres.2022.113562

Chemical characteristics and oxidative potential of indoor and outdoor PM_2.5 in densely populated urban slums

Environ Res. 2022 Sep;212(Pt D):113562. doi: 10.1016/j.envres.2022.113562. Epub 2022 May 24.

Authors

Abhay Anand¹, Suman Yadav¹, Harish C Phuleria²

Affiliations

¹ Environmental Science and Engineering Department, IIT Bombay, Mumbai, 400076, India.
² Environmental Science and Engineering Department, IIT Bombay, Mumbai, 400076, India; Interdisciplinary Programme in Climate Studies, IIT Bombay, Mumbai, 400076, India. Electronic address: phuleria@iitb.ac.in.

PMID: 35623440
DOI: 10.1016/j.envres.2022.113562

Abstract

A significant proportion of population in metropolitan cities in India live in slums which are highly dense and crowded informal housing settlements with poor environmental conditions including high exposure to air pollution. Recent studies report that toxicity is induced by oxidative processes, mediated by the water-soluble PM chemical components leading to reactive oxygen species production thereby causing inflammatory disorders. Hence, for the first time, this study assessed the chemical characteristics and oxidative potential (OP) of indoor and outdoor PM_2.5 in two slums in Mumbai, India. Daily gravimetric PM_2.5 was measured in ∼40 homes each in a low- and a high-traffic slum and analysed for 18 water-soluble elements and organic carbon (WSOC). Subsequently, OP was assessed through the Dithiothreitol (DTT) assay. Average WSOC was similar in indoor and outdoor environments while the water-soluble concentrations of total elements ranged 4.5-6.5 μg/m³ indoors and 6.4-19.2 μg/m³ outdoors, with S, Ca, K, Na and Zn being the most abundant elements. Spatial distributions of indoor concentrations were influenced by outdoor sources such as local traffic emissions for Cd, Fe, Al and Zn. The influence of outdoor-origin particles was enhanced in homes reporting high air exchange rates. OP was higher outdoors than indoors in both low-traffic slum (0.04-0.51 nmol min^-1m^-3 outdoors and 0.02-0.38 nmol min^-1m^-3 indoors) and high-traffic slum (0.03-1.06 nmol min^-1m^-3 outdoors and 0.04-0.77 nmol min^-1m^-3 indoors). Outdoor and indoor OP was also more influenced by outdoor road dust showing significant correlation with tracer elements Cu and Al (r ≥ 0.45; p < 0.05). Similar to OP, the non-carcinogenic health risk associated with indoor PM_2.5 were also higher in high-traffic slum (Hazard Index, HI = 1.60) than in low-traffic slum (HI = 0.43). Overall, this study shows that the indoor PM_2.5 and its chemical constituents in Mumbai slums are primarily of outdoor origin with higher toxicity and non-carcinogenic health risk in high-traffic slums.

Keywords: Indoor air pollution; Oxidative potential; PM(2.5); Urban slums; Water-soluble metals.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Air Pollutants* / analysis
Air Pollution, Indoor* / analysis
Dust / analysis
Environmental Monitoring
Oxidative Stress
Particle Size
Particulate Matter / analysis
Poverty Areas
Water

Substances

Air Pollutants
Dust
Particulate Matter
Water