The reason why everyone is lost in the number game over pollution is because health is the missing link in the conversation
For the first time in India, the Union Ministry of Health and Family Welfare has assessed and asked for “health” to be the central focus of air pollution control in the country. I am told this is the first ever instance in the world where health ministry has taken air pollution on board as a health issue.
This is a significant step forward keeping in mind that air pollution control is currently managed and monitored by the Union Ministry of Environment, Forests and Climate Change under the Air Act, 1986, which does not even have health risk mitigation as its stated objective. Cities are mindlessly monitoring air quality and assessing air pollution sources without linking the exercise with health risk mitigation.
A report from the “steering committee on air pollution and health related issues”, put out a few months ago, has brought some sanity in the insane obsession with ambient pollution concentration and the constant fight for determining relative share of pollution sources to the overall ambient pollution concentration. It says very clearly, pollution exposure management is more important from health stand point than only management of pollution concentration in the ambient air.
It is more important to know how close we are to the pollution source, what are we inhaling, and how much time we spend close to the pollution source than what occurs generally in the air that is influenced by climate and weather. Ambient concentrations measurement is easier to calculate change over time, “but does not always well represent true human exposures, which can be heavily influenced by nearby sources that do not always affect general ambient concentrations.” Therefore, cook stoves, vehicles or trash burning in neighbourhood are more health damaging than a source at a distance.
This new science takes us away from the conventional approaches to source apportionment. Newer methods are now applied to assess the emission by a source close to us and how much of it is inhaled through direct exposure. The report says it is important to assess pollution sources in the micro environment where people spend most of their time.
While control of pollution from all pollution sources over a larger geographical area is needed to reduce overall concentration, simultaneous exposure management is needed to prioritise pollution sources.
The report says exposure assessment research has shown that in many situations, ambient concentration is not a good surrogate for total air pollution risk, because it fails to accurately indicate exposure or dose and the health outcome. “Dose, a measure of change in the body due to pollutant exposures, can be an accurate measure of potential effect,” it says.
Pollution sources to be ranked as per exposure
If health exposure–how much and what we inhale–is the focus then it can dramatically alter the standard practice of ranking pollution sources, conventionally done on the basis of their relative contribution to ambient concentration. It states, “If pollution sources are evaluated and ranked based on exposure, it will not only re-order the ranking of major outdoor emission sources but will reveal an entirely different landscape of sources; those that may significantly affect exposure without appreciably affecting ambient concentration.”
If such criteria are applied, then local sources in households and neighbourhoods can cause more exposure to toxic pollutants than the large-scale industrial sources at a distance. To illustrate this point, the report has given estimates of relative contribution of different pollution sources to the ambient PM2.5 concentration and to the PM2.5 exposure in Chennai, Vishakhapatnam and Hyderabad.
This is an eye opener. In Chennai for instance, vehicles contribute 45 per cent of ambient PM2.5 concentration but its share increases significantly to 63 per cent in terms of exposure. Similarly, while share of industry in Chennai to ambient PM2.5 concentration is 20 per cent its share in exposure reduces to 12 per cent. In Vishakhapatnam, power plant contributes 37 per cent of ambient PM2.5 concentration but only 12 per cent of PM2.5 exposure. In Hyderabad, vehicles share in ambient PM2.5 is 38 per cent but 43 per cent in exposure.
The message is clear. In longer term, India will have to reduce pollution concentrations to acceptable levels for all health damaging pollutants in all places where people are. But a focus on total population exposure will help to prioritise control options and help in choosing the most effective strategies to reduce or eliminate exposure to health-damaging pollutants. This will also be more cost effective.
The report also cautions that integrated exposure matters the most and therefore outdoor and indoor pollution should not be treated separately. In fact, World Health Organization’s (WHO) “Global Burden of Disease” estimate for India has shown that indoor pollution from cooking stoves contributes as much as 25 per cent of outdoor pollution across India. If premature deaths due to indoor and outdoor air pollution are combined then air pollution is the top killer in India.
This makes health sector involvement in air pollution management critical. The United Nations General Assembly’s Political Declaration on Non-Communicable Diseases (NCDs) in 2011 adopted global targets to reduce illness and deaths from NCDs by 25 per cent by 2025. It highlighted exposure to air pollution as a key risk factor across South Asia. The World Health Assembly 2015 has also adopted a resolution to address the health impacts of air pollution–the world’s largest single environmental health risk.
India already has an enormous NCD burden, especially cancer risk. According to a forecast by National Cancer Control Programme (NCCP), cancer numbers will explode in India by 2026. NCCP has listed exposure to environmental carcinogens as one of the most important reasons of this increase. The mitigation strategy must reduce environmental risk from all factors–of which air pollution is the most important. The WHO has listed air pollutants as carcinogens. Diesel emission is a class-1 carcinogen for its strong link with lung cancer.
Prioritising pollution sources
The reason why everyone is lost in the number game over pollution sources and concentration, is because health is the missing link in the conversation. Exposure management is expected to set this right. Kirk Smith of the University of California, Berkeley, who was the advisor to this initiative, has personally worked extensively on health exposure from indoor cooking stoves (that still affects 700 million people in India) says, the principle of exposure assessment is that if one is worried about health, one has to measure where people are and control accordingly. Chulha, vehicles, trash burning or any other source under our nose matter more. These need priority action.
As a side note, I always find it amusing to recall the desperation that we see in the city to prove that vehicles don’t matter as they are only 20 per cent of the PM2.5 problem. The odd and even scheme in Delhi stoked ugly spat between cynics and supporters over the claims of air pollution cuts during that fortnight. Skeptics disputed evidences that showed how particulate pollution had reduced after car numbers were nearly halved. Everyone fought over ambient pollution concentration but no one asked about the health benefits of reducing exposure to toxic fumes in the breathing zone of most people in Delhi.
The IIT Kanpur data was interpreted to claim vehicles are a minor cause of pollution while the biggest problem is road dust–not acknowledging that vehicles are the second largest contributors of particulates. They also contribute significantly to secondary particulates formed from the gases emitted from tailpipes and chimneys. Moreover, vehicles spew some of the deadliest carcinogens and mutagens on our faces; exposure to traffic fume can immediately trigger cardiac symptoms.
Let us not lose the real focus of our fight against air pollution inside homes of the poor and outside. It is now official–what we inhale matter more. While looking up for a blue sky let us also look around us and take charge of our neighbourhoods and our travel routes to demand action on chulhas, vehicles, trash burning, construction dust to reduce exposure. Even while scanning air quality monitors to know the pollution concentration, demand to know what are we inhaling more and what it is doing to our lungs, brains, our organs, reproductive health and the unborn child.
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