There is an emergent need for stringent controls over air pollution which remains a major cause of mortality and aggravates several other health complications
Delhi ranks as the most polluted capital city globally despite air quality improvements during 2019-2020. The progress is only marginally attributable to India's flagship National Clean Air Programme (NCAP). The January 2019 scheme targets PM 2.5 reductions of 20-30 per cent in 122 selected cities by 2024 from the 2017 baseline. The 'World Air Quality Report, 2020', shows that Bangladesh, China, India, and Pakistan account for 49 of the 50 most polluted cities in the world. Delhi fares the worst in the world capital city rankings. The second-most populous city in the world is located southeast of India's agricultural breadbasket where open burning is common. Notably, India showed an overall improvement in several cities, with 63 per cent reporting direct improvements over 2019 averages.
Polluted air is a public health hazard, long-term exposure to which enhances the risks of cardiovascular and respiratory diseases. Scientists have linked air pollution with many health complications including asthma, heart disease, lung cancer and premature death. Among air pollutants, fine particulate matter is especially harmful as the tiny particles (diameter of 2.5 microns or less) can penetrate deep within the lungs with a low probability of being exhaled out. The concern remains that ultrafine particles with a diameter smaller than 0.1 micron (PM 0.1) could be particularly harmful, as they can directly pass into the bloodstream and affect other organs. Researchers reported that the smallest fraction of PM 0.1 can directly translocate into the circulatory system and accumulate at sites of vascular inflammation.
The mortality caused by ambient air pollution is highest in East Asia (35 per cent) and South Asia (32 per cent), followed by Africa (11 per cent), Europe (nine per cent) and North and South America (six per cent). The lowest mortality rate is found in Australia (1.5 per cent) which has set the strictest air quality standards than all other countries. Among the different types of air pollutants, PM 2.5 consisting of particles smaller than approximately 2.5 microns is responsible for an estimated 4.2 million premature deaths every year globally. This includes over a million deaths in China, over half a million in India, almost 2,00,000 in Europe, and over 50,000 in the United States. India continues to dominate annual PM 2.5 rankings by a city, as 22 of the top 30 most polluted cities globally are India. Major sources of air pollution in India include transportation, biomass burning for cooking, electricity generation, industry, construction, waste burning, and episodic agricultural burning. Transportation is one of India's leading PM 2.5 emission sources responsible for emitting pollutants and re-suspending road dust.
The reduction in life expectancy caused by air pollution is higher than many other risk factors such as smoking, infectious diseases or violence. Air pollution caused 8.8 million premature deaths worldwide in 2015. This corresponds to an average reduction in life expectancy per capita of 2.9 years. In comparison, tobacco smoking reduces the life expectancy by an average of 2.2 years (7.2 million deaths), HIV / AIDS by 0.7 years (1 million deaths), parasitic and vector-borne diseases such as malaria by 0.6 years (600,000 deaths). Air pollution exceeds malaria as a cause of premature death by a factor of 19; it exceeds violence by a factor of 17 and HIV / AIDS by a factor of nine. In reference to PM 10 pollution, it is pertinent to mention that researchers reported a significant linear relationship between long-term exposure to PM 2.5 and the rapidity of COVID-19 spread. The presence of secondary inorganic components in PM 2.5 aggravates the severity of human suffering.
According to researchers, the viral entry of SARS-CoV-2 uses Angiotensin-converting enzyme 2 (ACE2) as its co-host receptor that plays a crucial role in lung protection by cleaving and converting angiotensin II (Ang II) to the cardioprotective angiotensin 1-7. Viral loads of SARS-CoV-2 deplete residual ACE2 activity and impair host defences. This causes an imbalance between Ang II and Ang 1–7, resulting in high circulating levels of Ang II, which induces pulmonary vasoconstriction, inflammation, and oxidative stress. Thereby long-term exposure to pollutants had rendered the nationwide population susceptible to the virus spread plausibly via the "double-hit phenomenon". The huge adverse impact on public health and the global population is the indication of an "air pollution pandemic".
Central and state governments in India have adopted unprecedented measures to protect people from COVID-19 but they are not serious enough to avoid the millions of preventable deaths caused by air pollution every year. The report prepared by Swiss organization, IQAir in 2020 helps us realize that our efforts and actions to reduce the invisible killer, i.e., air pollution are not at all adequate and we have to put sincere efforts to prevent air pollution rapidly on a massive scale and in different manner to save hundreds of thousands of lives every year. The preventive measures taken by regulatory authorities to abate air pollution are too little and too late. This air pollution is not only restricted in Delhi or other cities as reported by the Swiss Organization, it is now everywhere in India. Wherever we start placing pollution monitoring equipment, we will realize that the air we breathe is toxic.
According to the findings of the study, almost two-thirds of the deaths caused by air pollution, numbered around 5.5 million a year, are avoidable and the majority of polluted air comes from the use of fossil fuels. The average life expectancy worldwide would increase by more than a year if the emissions from the use of fossil fuels were eliminated.
The first line of defence against this carnage is ambient air quality standards. Over half of the world's population lives without the protection of adequate air quality standards. The weakest air quality standards are often violated, particularly in India. In contrast, the strictest standards are often met in places like Canada and Australia. Therefore more than half of the world urgently needs protection in the form of adequate PM 2.5 ambient air quality standards. Putting the strictest standards in place everywhere will save countless lives. Where standards are already in place, they should be harmonized globally. High population density is not necessarily a barrier to fighting air pollution successfully. Several regions with densely populated areas have been successful in setting and enforcing strict standards. These include Japan, Taiwan, Singapore, El Salvador, Trinidad and Tobago, and the Dominican Republic.
To improve air quality in the future, more drastic reductions of emission from regulated sources such as power plants and vehicles and under-regulated sources such as manure management, changing personal diets and improved formulations of cleaning supplies, paints, inks etc are needed urgently.
The million-dollar question in this context is whether there is enough political will to aggressively fight the health emergency India faces today and move away from polluting fuels and practices? This is high time to appeal to our leaders to frame long-term measures otherwise humanity would be in danger. Governments have to realize that the real aim is pollution control and not any lecture or excuse. We should not be mute spectators to what is happening today in the name of pollution control.
The writer is a former Senior Scientist, Central Pollution Control Board. Views expressed are personal