Lahore, New Delhi, Peshawar, Beijing. Recently newspapers and social media carried photographs of these cities covered in smog. Children and the elderly were particularly affected in Lahore with several consultations for exacerbations of chronic bronchitis and asthma.
What is pollution?
Everyone has a right to clean air yet we don’t get to breathe it in most cities. The presence of harmful gases and particles in air is pollution. Smog is derived from smoke and fog, when pollutants descend in the form of fog creating a haze and irritation in the throat and chest.
Some pollutants can’t be seen but are just as harmful as the thick black smoke emitted from factories, diesel engines including vehicles and generators, brick kilns, and burning trash and leaves. In the countryside smoke results from burning firewood for cooking, setting fires to fields after crop harvest, tractors, tube wells powered by engines and vehicular traffic.
Forty years ago power was mostly generated from coal plants in many countries. The London smog of 1952 caused 4000 deaths. In 1964 the clean air act was passed for clearing out air pollution.
One in every five people is particularly at risk from air pollution. These include the elderly, very young children, pregnant women, and people suffering from diseases like asthma, chronic bronchitis, emphysema and coronary heart disease.
Which pollutants cause the problems?
Sulphur dioxide (SO2) is produced by coal burning, power stations and diesel burning. It narrows down air passages making breathing difficult. This is a particular problem for young children, asthmatics and patients with emphysema.
Smoke is produced by coal burning, power stations, traffic, kilns and any other form of large scale burning. Large smoke particles are trapped in the upper air passages, but the smaller particles can travel deep into the lungs. These particles include cancer causing polyaromatic hydrocarbons.
Nitrogen dioxide (NO2) belongs to the family of oxides of nitrogen (NOX). These are produced by burning of fuel in motor vehicles and power plants. It irritates the lining of the bronchial tubes in the lungs. Its levels are high along busy roads, and can make breathing difficult for asthmatic patients.
Ozone is the main ingredient of photochemical smog. It is found when NOX and hydrocarbons combine in sunlight. Ozone irritates the lungs causing coughing and chest pain. It also stings the nose, throat and eyes, and may cause headaches. People with lung disease and people exercising are particularly at risk when ozone levels are high.
Carbon monoxide (CO) is odourless and very poisonous. It comes mainly from traffic exhaust. It interferes with the ability of the blood to carry oxygen to the brain, heart and other tissues. People with heart disease are particularly at risk. CO may also retard the growth of unborn children. Cigarette smoke is another source of CO, and smokers have much higher levels in blood than non-smokers.
Diesel exhaust emits smoke and thus more cancer causing chemicals than petrol smoke.
Lead threatens the normal development of children. Lead was present in petrol but levels have declined since the use of lead-free petrol. Lead is added as an anti-rusting agent to paints. Burning or melting such painted objects e.g. ship hulls releases lead in the air. A study done in the 1980s in the Kot Lakhpat area of Lahore — where such plants are located – and published in the Science of the Total Environment revealed high lead levels in the blood of residents of the area. Lead was found in particles settling on food sold by streetside vendors.
Acid air occurs during episodes of photochemical smog when NO2 and SO2 are converted into acid, particularly nitric acid and sulphuric acid. These form into clouds of tiny acid droplets. They damage trees and other plants. When breathed in they cause irritation of the airways, coughing and even wheezing.
What can you do to protect yourself against air pollution?
People who are exposed to pollution for any length of time, such as cyclists, traffic police, couriers, or those involved in any type of outdoors work, should consider wearing an appropriate mask. This is especially important for people who are prone to chest infections or suffer from chronic lung disease.
People are advised to avoid strenuous exercise when pollution levels are high, particularly ozone levels. Most governments issue ozone alerts.
At risk groups such as pregnant women, very young children, the elderly and those with chronic lung disease or heart disease should best stay indoors.
Governments must take up the responsibility of ensuring clean air for all. It is the collective responsibility of road users, business, industry and governments to cooperate to achieve this objective.