Delhi’s Air Quality Index (AQI) is touching 500. The prevailing air pollution crisis in India in general and the National Capital Region (NCR) in particular is a concern for everyone — and AQI has firmly established itself in the household vocabulary. A range of restrictions including the odd-even scheme have been enforced in Delhi by the local administration while the Bombay High Court has taken suo motu cognisance of the poor air quality in Mumbai. Pollutants of major public health concern include particulate matter (PM10 and PM2.5), a mix of solid and liquid droplets arising mainly from fuel combustion; nitrogen dioxide from road traffic; ozone at ground level caused by the reaction of sunlight with pollutants from industrial facilities and vehicle emissions; and sulphur dioxide, an invisible gas from burning fossil fuels like coal. Air pollution is generally on the decline in advanced economies and rising in emerging and industrialising economies. In the aggregate, the WHO cautions that nearly 90 per cent of the global population breathes air that exceeds prescribed limits and contains high levels of pollutants. The worst affected are the low- and middle-income countries. Recognising a growing global concern about deteriorating air pollution, the World Health Assembly Resolution 68.8, ‘Health and the environment: Addressing the health impact of air pollution’, was endorsed by 194 member states in 2015. An estimated eight million deaths globally were attributed by the WHO to air pollution. Delhi was flagged as the most polluted city with an annual mean of fine particulate matter of 153 μg/m3 compared to 17 μg/m3 in Paris and 8 μg/m3 in Toronto. India featured among the top 15 countries with the highest annual mean of fine particulate matter (PM2.5). Afghanistan, Bangladesh, China, and Pakistan also figured in this list, highlighting the vulnerability in this part of the world. The Resolution called for better policies to promote cleaner public transit and clean-energy sources, and reduction of emissions of carbon dioxide, methane, and black carbon. Measurement of AQI is done by air monitors and air pollutant concentration over a specified averaging period. The results are then grouped into ranges; each range is assigned a descriptor, a colour code, and a standardised public health advisory. Multiple pollutants may be measured at a monitoring site, in which case the biggest AQI value in one hour on average is reported for that location. The US-EPA AQI is divided into six categories — 0-50 (green) represents “good” air quality and 301 and higher (maroon) represents “hazardous”. India’s National Air Quality Index Standard (NAQI) has a range of six categories with “severe” representing values of 430 and above. PM2.5 levels in Delhi are about 15 times higher than the prescribed WHO guidelines. India’s National Clean Air Programme (NCAP) was launched in 2019 to achieve a 20-30 per cent reduction in concentrations of PM10 and PM2.5 by 2024 (base year, 2017). It encompasses a wide range of specific interventions including reduction of vehicular pollution through regulatory norms, promotion of public transport and improvements in roads and bridges; tackling industrial emissions; notification of eight waste management rules; monitoring of ambient air quality; and prevention and control of paddy stubble burning. Associated with oxidative stress and inflammation in human cells, air pollution plays a key role in the genesis of chronic diseases and cancer. Public health consequences include cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders. A third of the deaths from stroke, lung cancer and heart disease have been linked to air pollution; an equivalent effect to smoking tobacco, and higher than the effects of over-consumption of salt. Air pollution has been linked to higher chances of developing several neurological disorders including Parkinson’s disease, Alzheimer’s disease, and other dementias. Children are especially vulnerable owing to a set of unique reasons: Air pollution affects their developing lungs; they are less capable to metabolise, detoxify, and excrete air pollutants; neurotoxic compounds in air pollution can affect children’s developing brains and cognitive development; they inhale more air per unit of body weight than adults; they are physically more active and breathe in more air pollution; and, babies born to women who exposed to air pollution during their pregnancy are more likely to be premature and low birth weight. It is often somewhat naively argued that air pollution is a great leveler, affecting the rich and the poor alike since everyone breathes the same air.
An airshed is an area where local topography and meteorology limit the dispersion of pollutants. The Leaders’ Declaration under the Indian G20 Presidency focussed on addressing pollution in the context of climate action and promoting the One Health approach. As a leader of the global south, India’s NCAP should build on these synergies.
A recent study in Delhi had observed that PM2.5 levels inside richer homes were not significantly lower than those found in poorer homes. Well-designed ecological studies in the UK and Europe found that like most other health events, air quality often exhibits a social gradient — higher deprivation indices and low economic position are usually linked with higher levels of pollutants such as particulate matter. Differences in exposure between groups lead to differences in morbidity and mortality. An important learning from these studies is that there are no safe thresholds, particularly for particulates and ozone; effects seem to be linked to the level studied. This explains the need to evolve more stringent air quality standards and find ways to implement those. The Parma Declaration 2010 by the European governments is instructive in this context. The NCAP recommends the odd-even scheme with minimal exemptions for Delhi in case of Severe+ conditions. There seems to be a consensus among engineering experts that this may not be a good long-term measure. A study of the 2016 restrictions observed an average reduction of PM2.5 by 5.73 per cent and that of PM1.0 by 4.70 per cent. Another study observed substantial reduction in tailpipe emissions without any improvement in overall ambient air quality. Experience from other megacities such as Beijing, Jakarta and Mexico City suggest that sir quality is not significantly improved as various gaming measures such as substitution to relatively older vehicles on restricted days and cover or borrow licence plates come into play. The scheme continues to be popular with politicians and bureaucrats. An analysis of city-level clean air action plans found that transport and road dust together covered 50 per cent of action points. The One Health approach has traditionally focussed on infectious diseases in relation to zoonoses, food safety and antimicrobial resistance. The Berlin Principles on One Health, 2019, recognise that decisions regarding land, air, sea, and freshwater use directly impact the health and well-being of humans, animals and ecosystems. Alterations in ecosystems paired with decreased resilience generate shifts in communicable and non-communicable disease emergence, exacerbation and spread. It, therefore, urged that actions be taken to eliminate or mitigate these impacts. There is also an emerging consensus on transitioing from city-centric to airshed-centric air quality management. An airshed is an area where local topography and meteorology limit the dispersion of pollutants. The Leaders’ Declaration under the Indian G20 Presidency focussed on addressing pollution in the context of climate action and promoting the One Health approach. As a leader of the global south, India’s NCAP should build on these synergies. (Courtesy……………………………. indianexpress.com. The views, opinions and conclusions expressed in this article are those of the author and aren’t necessarily in accord with the views of “Kashmir Horizon”.)