When, Where and What? Measuring Personal Exposure to Air Pollution in India

Of the 12 most polluted cities in terms of particulate matter (PM_2.5), 11 are in India. A new study led by the Barcelona Institute for Global Health (ISGlobal), an institution supported by ”la Caixa” Foundation, has used a combination of techniques to better identify factors that influence personal exposure in a periurban region of India: the time of the day (when?), the location (where?), and the individual’s activities (what?).    

Low and middle-income countries often register high levels of air pollution, and the exposure sources are probably different from those in high-income countries. However, few studies have measured personal exposure to air pollutants in these regions. A previous study by the CHAI project, coordinated by ISGlobal, used a combination of wearable cameras and air pollution monitors for the first time. 

Now, the CHAI team characterised personal exposures of 50 participants in periurban Hyderabad, Telangana, in South India, during various 24-hour sessions. To do so, they integrated data from GPS devices, wearable cameras, questionnaires, and ambient and personal PM_2.5 concentrations. 

The results, published in Environmental Science & Technology, indicate that there are significant differences between men and women. The average personal exposure to PM was higher in men than in women (43.8 and 39.7 μg/m³, respectively), with both values way above the maximum levels considered as safe by the World Health Organization (10 µg/m³).

While women were more exposed in the morning, men were more exposed during the rest of the day. A large proportion of PM_2.5 exposure occurred at home – 67% for men and 89% for women, which was proportional to the time spent in this location.  

Women were exposed mainly through cooking activities. For men, activities related with high exposures included vicinity to food preparation, smoking, or industry. The ambient pollution levels were predictive of personal exposure for all participants. 

Based on these results, ISGlobal researcher and first author of the study, Carles Milà, underlines that “measures to reduce air pollution exposure should prioritize access to clean energies in the kitchen.” This intervention would reduce exposure among women and men who, even if they do not cook, do spend time in the kitchen.   

ISGlobal researcher Cathryn Tonne, coordinator of the study and of the CHAI project, notes that the research “demonstrates the potential of integrating multiple data sources to gain insights into drivers of personal exposure.” This study “is a small example of what exposure assessment could look like in future environmental epidemiology research,” she adds.

Reference

Carles Milà, Maëlle Salmon, Margaux Sanchez, Albert Ambrós, Santhi Bhogadi, V. Sreekanth, Mark Nieuwenhuijsen, Sanjay Kinra, Julian D. Marshall, and Cathryn Tonne. When, Where, and What? Characterizing Personal PM2.5 Exposure in Periurban India by Integrating GPS, Wearable Camera, and Ambient and Personal Monitoring Data. Environmental Science & Technology, 31 de octubre de 2018. 10.1021/acs.est.8b03075