Pollution is the presence of a wrong thing, in the wrong place, in the wrong quantity, and at the wrong time. It is evident that such a thing will prove harmful. Air pollution is one of India’s primary killers. The country accounts for 60 per cent of the global deaths attributed to foul air and has also the dubious distinction of being home to 16 out of 20 of the world’s most polluted cities according to the World Health Organisation’s global PM2.5 (finer particulate matter) database. Air pollution does not respect the etiquette of borders. It blows with the wind into and out of urban centres, undermining localised efforts to control it.

While air pollution affects everyone, children are particularly vulnerable because their respiratory systems (lungs and their airways) remain in a developing stage and are not mature enough to cope with the onslaught of oxidant-induced injury caused by toxic air pollutants. Moreover, children have an underdeveloped detoxification machinery with weak anti-oxidant defence that may result in permanent alterations in the lungs. There is a growing interest among scientists to assess the regional build up and profile of pollution by using high resolution satellite data and utilising methods like aerosol optical depth. For instance, scientists at the IIT, Delhi, and the Indian Institute of Tropical Meteorology (IITM) are tracking the nature and shifts in the build-up of air pollution peaks in the IndoGangetic Plain.

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Moreover, interest has grown in the episodic pollution caused by the movement of smoke from crop stubble burning in Haryana and Punjab across the regions. Globally, governments are seeking answers to this challenge. At the international levels, there are inter-governmental treaties and agreements on trans-boundary air pollution. But in the words of Al Gore, Nobel Laureate and former US Vice President: “The struggle to save the global environment is in one way much more difficult than the struggle to vanquish Hitler, for this time the war is with ourselves. We are the enemy, just as we have only ourselves as allies.” Scientists typically measure rates of air pollution through concentrations of ozone and particulate matters.

Particulate matters consist of airborne suspensions of extremely solid or liquid particles, such as soot, dust, smoke, fumes, and mist. The US Environmental Protection Agency (EPA) and other regulatory agencies generally recognise two major types: PM10 (airborne fine particles with a diameter of 10 microns or less) and PM2.5 (airborne finer particles with a diameter of 2.5 microns or less). PM2.5 is about 30 times finer than the thickness of human hair. Ultrafine particles (PM1) are 70 times (or more) finer than the thickness of human hair.

The general rule for particulate pollutants is that the finer they are, the deeper they go, and more damage they cause. Moreover, PM1 also contains more toxins (including metals) from anthropogenic emissions, which can cause deeper lung injury and even lead to gene damage and cancer. These ultrafine particles are so fine that they can enter the bloodstream and cause the degeneration of blood brain barrier, leading to oxidative stress, neuro-inflammation and brain damage. Victims become more vulnerable to neurobehavioral disorders which may culminate into cognitive impairment (low IQ), behavioural problems and attention deficit hyperactivity disorder (ADHD).

Till now, not much deep research has been carried out on the effects of PM1 on human health. Pregnant women inhale an increased amount of air per minute. As a result, they are exposed to some pollutants, particularly PM2.5, originated from the use of inefficient polluting fuels and technologies and or from second-hand smoke which can cross the placenta and reach the foetus. Such exposure to PM2.5, particularly during the third trimester of pregnancy, may have effects on neurodevelopment.

Exposure impacts lung development and respiratory health that may persist throughout childhood and also affect the immune system, causing enhanced morbidity. Exposure to fine particles can cause short term health effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath. Particulate matter, particularly the finer PM2.5 travels deep into the respiratory tracks and causes lung damage, pneumonias, upper respiratory tract infection, asthma, altered growth (stunting and obesity), high blood pressure, childhood leukaemia and impaired cognitive development.

Exposure to both particulate matters ~ PM2.5 and PM10 ~ can aggravate numerous health problems mentioned above. While air pollution affects everyone, the tragedy is that the worst victims of air pollution are the ones who have contributed the least to it ~ children. Globally, 93 per cent of children live in environments where air pollution levels are higher than what World Health Organisation (WHO) guidelines recommend. Air pollution has lifelong health implications for children. One out of every 14 children born died before reaching the age of five. Children are vulnerable air pollution predominantly due to the following reasons:

* Children spend a lot of time outdoors, playing and engaging in physical activity in potentially polluted air (ambient air pollution).

* Children are physically more active; they also have higher metabolic rates and their breathing rates are faster (20-30 breaths per minute compared with 12 -16 breaths per minute in adults). Children thus inhale more air per kg of body weight than adults, and, with it, more air pollutants.

* Owing to their shorter height, children also breathe air closer to the ground where some pollutants including PM2.5 and PM10 are present in higher concentrations.

Their vulnerability seems to be aggravated because they take in a larger fraction of air through their mouths than adults, as a result of which pollutants penetrate deep into the lower respiratory tract. Additionally, they are handicapped because of the ineffectiveness of their nasal filtering capacity and underdeveloped immune system. Particulate matters are produced by both primary and secondary sources. Primary particulate matter is emitted directly from construction sites, wildfires, wood burning, gravel pits, agricultural activities, volcanoes, and dusty roads.

Secondary particulate matter is formed in the atmosphere through complex chemical reactions. PM2.5 precursors are nitrogen oxides (NOx), volatile organic compounds (VOCs) and sulphur dioxides (SO2). And ammonia contributes to the formation of secondary fine particulates. Precursors that lead to the formation of PM2.5 are emitted by a variety of sources, including power plants, industry, vehicles, small businesses, buildings and homes. The world’s attention has been focussed on one health issue over the past years: Covid19.

But substantially inadequate attention is paid to a persistent and insidious problem. We often gloss over the extent to which indoor pollution can jeopardize the health of our rural women and children. Life in a typical household revolves around the cooking areas. Women spend considerable time in cooking and maintaining the kitchen while raising children alongside. Women and children are exposed to indoor air pollutants.

They breathe toxic air loaded with unsafe levels of particulates matters (PM2.5) as emanates from openfire traditional cook stoves (Chulhas), or by use of solid fuels (which refers to both coal and biomass fuels, such as firewood, charcoal, dung, agricultural residues and sometimes leaves and grass).

Chulhas using solid cooking fuels release smoke equivalent to 400 cigarettes every hour. Cooking is often done in poorly ventilated conditions. Besides, most households do not have a separate kitchen and cooking stoves are used for several hours each day which generates significant indoor pollution. There is substantial data available in India, and globally, on the link between solid fuel use in households and the health consequences for women. Newborn and infant children are more susceptible to indoor air pollution, as they are near their mothers while they cook with the polluting fuels and devices.

(The writer is a retired IAS office)