The air quality of the National Capital Region has assumed alarming proportions. Actions initiated by the authorities to curb the menace is too little and too late and exposes gross negligence in management of the air quality index. On 12 October this year, a layer of haze lingered over the national capital and AQI plunged to ‘very poor’ category days before stringent measures to combat air pollution come into force under the Graded Response Action Plan (GRAP). AQI data according to the Central Pollution Control Board data revealed values exceeding 300 in many parts of the capital and adjoining areas. It should be borne in mind that an AQI between 0 and 10 is considered ‘good’, 51 and 100 ‘satisfactory’, 201 and 300 ‘poor’ 301 and 400 ‘very poor’ and 401 and 500 ‘severe’.

Despite the National Green Tribunal’s stricture, no respite for common people seems to be evident and the situation has deteriorated considerably. The closure of primary schools, entry of trucks, implementation of odd-even vehicle movement in the NCR and creation of artificial clouds for rain are nothing but short-term measures. Concerned with the deadly smog engulfing the capital, the NGT several months ago banned all construction and industrial activities in Delhi-NCR and ordered taking adequate steps to minimise dust contamination by sprinkling water on the roads.

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Chief Minister Arvind Kejriwal’s tweet describing Delhi as a gas chamber and habitual natural phenomenon during this season is a simplified take on an intricate problem. The maintenance of air quality standard is the primary duty of both the Central as well as the state government. It transpires now to have been the collective monumental failure of the governments, technocrats and bureaucrats.

The Union Environment Ministry constituted a committee to continuously monitor the air pollution menace. The Central Pollution Control Board (CPCB) and Environment Pollution (Prevention and Control) Authority (EPCA) would device a future course of action after meticulously assessing the situation.

A combination of smoke from stubble-burning in Punjab and Haryana mixed with fog are blamed for this hazard and the ‘smog’ thus produced permeates living rooms of homes. Despite a ban on stubble burning in Punjab and Haryana, the situation has not improved and farmers continue to defy the ban in the absence of financial incentives.

The air Indians breathe is turning more toxic by the day and an average of two deaths take place every minute due to the air pollution menace, according to noted medical journal The Lancet. It also substantiates that over a million Indians die or are at the point of death due to air pollution annually and some of the worst polluted cities of the world are in India including its capital.

The sub-particulate matter PM 2.5 exposure is responsible for this menace and climate change is associated with this phenomenon. In all the major cities of India – New Delhi, Patna, Kolkata. Mumbai and Chennai – the index of air pollution is far from satisfactory.

The Lancet however contradicted some Indian reports and pointed out clearly that coal-fired power plants contribute to 50 per cent of the ambient air pollution. The emissions from automobiles are also sources of mischief, including the incredibly dangerous contaminated polynuclear aromatic hydrocarbons (PAH) which are extremely carcinogenic.

The Lancet report clearly pointed out potential catastrophic risk to human health and need for immediate and meaningful environment management. The air pollution of Delhi and Kolkata as reported by World Health Organisation and United Nations Environment Programme has assumed alarming proportions during the last few decades.

The air we breathe is poisoned with anthropogenic and natural emissions all the time. However, air pollution is not a new problem. As long as man has lived in cities, he developed a propensity to pollute the air. It is a problem of the ever-expanding technological society. The situation has been accentuated by monstrous climatic change.

Most artificial impurities are injected into the atmosphere at or near the earth’s surface. Therefore, what is critical about air pollution is its scope and severity. It is well known that for most pollutants, the troposphere cleanses itself within a very short period of time because of the so called “vertical missing ability”. Rainfall also helps in removing the impurities to a certain extent, but acid rain damages the environment, now a matter of grave concern. Therefore, any substance that is not part of air’s gaseous make-up is regarded as a pollutant.

Air-borne suspended particulate matter (SPM), respiratory particulate matter (RPM) and contaminant gases exist in the atmosphere in various degrees. Air pollution is not confined to a particular territory but is a transboundary phenomenon. In major urban cities of India, the quality of air has been deteriorating rapidly over the past two decades.

The problem is particularly acute in major Indian cities and its suburbs where the air is unclean, according to standards fixed by WHO. The everincreasing urban population is also posing a serious problem. Emission from vehicles has been identified as the major source of pollution in the Delhi metropolitan region. The situation is appalling owing to the increasing number of vehicles and the limited space for their movement.

Other factors accentuating the problem are domestic consumption of fossil fuels, pollutants from small industries and godowns, multi-storied building and road construction, ever increasing number of vehicles, whimsical burning of agricultural waste and emissions of SPM from thermal power stations. The pollutants vary from one place to another. The intensity is highest in the heart of the city. Common air pollutants in Delhi are sulphur dioxide, oxides of nitrogen, carbon monoxide, hydrocarbons, peroxy acetyl nitrite (PAN), which causes irritation of eyes, heavy metals and traces of incredibly dangerous polynuclear aromatic hydrocarbons (PAH) which are carcinogenic in character.

Air pollutants exist in gaseous or particulate form. Their concentrations are expressed most commonly either in microgram per cubic meter (g to the power-3 of air) or as volume mixing rate (1 ppb =10 to the power-9 ) which are diverse in character.

The poor and the weaker sections of society are acutely affected by pollution. Pavement dwellers, underprivileged and vulnerable groups are exposed to direct health hazards. In addition, the heavy air pollution leads to higher rates of mortality and morbidity.

Leaded petrol has been banned in most developed countries. But unleaded petrol has other disadvantages which need special attention. Lead-free petrol releases a higher level of aromatic organic compounds and a high concentration of benzene which is known to be potentially carcinogenic. According to WHO, the risk of cancer is substantial. Suitable measures need to be taken immediately to eliminate the emission of toxic benzene into the air.

Given the horrifying level of air pollution in major cities of India including its capital, how is it that millions manage to survive? One probable explanation is that the ambient air pollutants are shared by millions of people and they act as biological filters. The body doesn’t immediately suffer any symptoms of danger, but they arise after a prolonged period of time.

As pollutants are chiefly the outcome of auto-emissions, the entire auto-emission regulatory process needs to be revamped. Reduction of vehicular emissions through continuous checks, strict enforcement of the law and periodical survey of the emission control equipment are vital. The air quality monitoring process should be strengthened.

The use of catalytic converters inside a car exhaust system has its benefits. The use of lead-free petrol in cars without converters is a great risk to public health. Personal exposure to benzene at service stations should be minimized. All service stations must display warnings about the risk of benzene exposure. Vehicles running on outdated technology should be immediately discarded. Developing suitable technology for manufacture of electrical cars, gradually replacing diesel and petrol vehicles, would be beneficial.

Planting more trees in the city can cleanse the air. The quality of fuel used in automobiles also helps curb air pollution. Samples need be analyzed regularly. The infrastructure must be suitably developed and on a priority basis. The equipment for continuous autoemission control, including mobile laboratories needs be utilised properly. Display of air quality information boards in prime areas of the city can also arouse popular awareness. Finally, the success of mitigating air pollution depends largely on popular participation and awareness of environmental health hazards.

The writer, a former Reader in Chemistry at Presidency College, Kolkata was associated with the UGC and UNICEF.