AIR POLLUTION

AIR POLLUTION IN DELHI AND THE HEALTH EMERGENCY

Ravindran Chetambath, Jesin Kumar C

Dept. of Pulmonary Medicine

DM Wayanad Institute of Medical Sciences, Kerala

Delhi, a city which was once known for the various architectural tourist attractions, is now a city smothered in smog which often compromises the visibility of these historic structures. As the festival of lights approached this year, the people of Delhi faced a dilemma that they have of late become familiar with. In a city where the growing levels of pollution have forced their residents to wear surgical masks outdoors; use of firecrackers seemed to only aggravate the problem. Hospitals in the ‘’world’s most polluted capital’’ have seen an increase in patients reporting with respiratory illnesses. Children residing in the city also develop irreversible lung damage at a very young age.

Environmental air pollution, the fifth largest killer in India, has probably been a constant source of health issues since the discovery of fire millions of years ago¹. Its use in cooking and heating purposes is still a major reason for respiratory illnesses. The rise in the number of power plants and motor vehicles in the city has resulted in the emergence of newer and more harmful pollutants like sulfur oxide, nitrogen oxide, ozone and polycyclic aromatic hydrocarbons in the atmosphere. It was estimated that about 3000 metric tons of air pollutants were emitted every day in Delhi, with a major contribution from vehicular pollution (67%), followed by coal-based thermal power plants (12%). There was a rising trend from 1989 to 1997 as monitored by the Central Pollution Control Board (CPCB). The concentrations of carbon monoxide from vehicular emissions in 1996 showed an increase of 92% over the values observed in 1989.

Since the atmosphere in Delhi contains a complex mixture of pollutants, it is often difficult to find out the individual health effects of each pollutant. Our respiratory system is equipped with defence mechanisms to protect us from these harmful pollutants. However, it is becoming increasingly difficult for our body to cope with the pollutants in Delhi due to its harmful properties. Particulate matter pollutants are classified based on their size into PM₁₀ (<10 µm diameter) and PM_2.5 (<2.5 µm diameter) particles. As per the Air Quality Index (AQI) data of 2019², Delhi now has a PM_2.5 level of 185µg/m³. This high level of minute PM_2.5 particles in our capital helps these substances to evade the filtration mechanisms in our nose and airways and penetrate the alveoli to spread to the other vital organs³. The oxidative burden posed by air pollutants like ozone, in Delhi, is often so large that it overwhelms the innate antioxidant system in our body⁴. The ensuing oxidative stress is linked to a wide range of diseases including, asthma, diabetes, cardiovascular disorders, Alzheimers disease, Parkinson’s disease, depression, infertility and cancer.

World Health Organization in September 2011 reported⁵ that Delhi has exceeded the maximum PM10 limit by almost 10-times at198μg/m³. Major concerns for human health from exposure to PM10 include effects on respiratory systems, damage to lung tissue, cancer and premature death. Elderly persons, children and people with chronic lung disease, influenza or asthma are especially sensitive to the effects of particulate matter. These pollutants can cause widespread airway injury like respiratory bronchiolitis and can also result in exacerbations of pre-existing respiratory illnesses like asthma and chronic obstructive pulmonary disease. The rise in the incidence of lung cancer, now becoming increasingly common in young never smokers, can also be attributed to these pollutants⁶. It was found that Delhi had 1.7-times higher prevalence of respiratory symptoms compared with rural controls (P < 0.001); the odds ratio of upper respiratory symptoms in the past 3 months in Delhi was 1.59 (95% CI 1.32-1.91) and for lower respiratory symptoms was 1.67 (95% CI 1.32-1.93)⁷.

The months of October and November are the months when Delhi really chokes. Inhaling the air during these months is equivalent to smoking 45 to 50 cigarettes per day⁸. The bursting of firecrackers during festivals hampers the hazardous atmosphere in Delhi. Unfortunately, the city is not entirely to blame for the predicament it finds itself in during these months. The burning of organic matter like crop residues in the states of Punjab and Haryana during these months have contributed to about 26% of the particulate matter in Delhi’s air⁹.

The trend of worsening air quality in Delhi is bound to continue if drastic measures are not implemented at the earliest. Measures taken by the chief minister like the implementation of the odd-even rule for vehicles and distribution of surgical masks to school children are steps in the right direction but need to be preceded by scientific studies to elucidate the quantity of air and the problem posed by these pollutants. These include large scale epidemiological studies, animal and in vitro research. Experimental studies subjecting animals or humans to varying concentrations of the pollutants in a controlled environment may be needed to elucidate the harmful effects of these pollutants. In vitro research helps to study the effects of these pollutants on a cellular level¹⁰.

The onus is on the people of Delhi to contribute in whatever way possible to curb this menace. Car-pooling and the use of bicycles, CNG filled cars and public transports are some ways in which vehicular emission can be controlled. Reforms by the government like improving the quality of public transport, marking out bicycle lanes on the roads and reducing taxes on CNG filled cars; can also aid in this¹¹. As far as industries in the suburb are concerned, drastic measures like shutting them down or relocating them are needed. It was reported that use of lower-emission motor vehicles resulted in a significant gain in disability-adjusted life-years in Delhi. Another study found significant evidence for reduction in respiratory illnesses following introduction of control measures¹².

The problem Delhi faces is huge and seems unsurmountable at times. However cities like Beiijng faced similar problems decades earlier and have managed to overcome them to a certain extent¹³. Enormous investment of time, resources and political will is needed in order to improve the air quality of Delhi. The thought of children being exposed to such hazardous air should propel us to act promptly. At least for them, let us take an oath to be a part of the solution and not the problem.

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