Both ambient and household air pollution have been identified as key health risks in India, and more than 50% of India’s population lives in areas where the air quality exceeds the annual PM2.5 standard (40 µg/m3). In the last couple of years, there has been a renewed focus on improving air quality in Indian cities, and in addition to legislative and court mandated action to improve air quality, there has been an increase in sales of indoor pollution monitors, masks and air purifiers indicating a direct interest from people.
While this is an important step forward, it is important to consider that personal exposure can vary significantly depending on age, gender, occupation and socio-economic status.
Personal exposure, simply put, takes into account the time we spend in different micro-environments (e.g. office, home, gym, restaurant and car/bus/train) and the pollution levels in these micro-environments. Factors such as poverty (especially energy poverty) and differences in quality of life can render certain sections of the population more susceptible to negative health effects linked to air pollution.
Air pollution levels tend to be higher in poorer neighbourhoods, and crowded conditions, use of polluting fuels and indoor smoking can further exacerbate indoor air quality levels. A study by the Central Pollution Control Board observed an inverse relationship between respiratory health and socio-economic status.
Exposure to Air Pollutants
Exposure to air pollutants can happen through two major routes – personal exposure to ambient or indoor air pollution during our day-to-day activities, and occupational exposure at the workplace. For example, consider the daily activities of a courier delivery executive, and an office worker – inevitably, the delivery executive will likely spend long hours on the road while the office worker will be inside a building, and while both will be affected by the ambient air, exposure level can be significantly different depending on road pollution levels and air quality inside the office.
There are many outdoor and indoor sources of air pollution that can contribute to pollutant exposure, including vehicles, industries, power plants, open waste burning, construction and generators in outdoor environments, and cooking, use of fuels such as wood, dung and coal inside houses, incense/candle burning, smoking and use of consumer products (deodorants, air fresheners, sprays etc.) inside buildings. Many research studies have shown very high levels of particles inside homes in India, although it is important to note that a majority of these studies were conducted in houses where solid fuels are used.
Improving Indoor Air Quality
Use of LPG or other cleaner fuels not only improves indoor air quality, but residents also report fewer adverse health effects such as respiratory illnesses. Cooking, especially frying, grilling or roasting, produces a large number of fine particles, and under inadequate ventilation conditions, can contribute to higher pollution exposure.
Use of exhaust fans, or ventilation systems can be one way to reduce cooking-related exposure to particles. Another contributor to indoor pollution, albeit seasonal, are mosquito coils, which are often burnt in summer/monsoon, and are known to contain toxic and carcinogenic compounds.
Pollution Control Strategies
Another activity associated with pollutant exposure is commuting. Studies across the world have shown commuting to contribute significantly to the daily exposure burden, and in India, daily traffic micro-environment exposures can often be as high as overall daily exposure to air pollutants in developed countries. Studies in India have come to different conclusions in terms of most polluting transport modes, but air-conditioned cars and buses seem to have relatively lower in-vehicle pollution levels. Since personal exposure takes into account pollution levels as well as time spent in the specific microenvironment, longer commute times (due to traffic jams, congestion etc.) can contribute to higher exposure levels.
Air pollution control/mitigation efforts need to be based on our understanding of how and when people are exposed to air pollutants, in order to maximise health benefits. A clear understanding of levels of personal exposure to air pollutants and associated health effects can not only help us learn more about the links between exposure and health effects but more importantly, improve the overall quality of life through targeted interventions.
As cities expand, and new cities and towns emerge, large numbers of people are living in close proximity to pollution sources, increasing the risk of exposure to pollutants, and in order to minimise health effects, it is imperative that pollution control strategies take into account people’s activities and exposure.
(The writer is a researcher at the University of Massachusetts, Amherst (USA) and studies air pollution in India)