Is outdoors really ideal?

Dr Peeyush Jain

Thanks to the growing awareness of the benefits of regular exercise, the number of enthusiasts taking up exercise on a regular basis too is rising. This is evident from the number of health clubs that have mushroomed all over the country in the recent past. A greater part of people availing these facilities comprises the young and figure conscious, rather than those with heart disease, diabetes or arthritis. Incidentally, it is the latter, who will benefit the most from regular exercise. In our country, most of the people who need to exercise regularly as a form of therapy, exercise outdoors. But there are important differences between indoor activity and exercise in the open. While it is possible to regulate the physical environment within a closed space, there is no such control outside.

As a majority of people exercise outdoors, it is pertinent to ask whether our environment is really suitable for outdoor exercise. This is important as our urban environment is deteriorating due to rising population density and lack of efforts by regulatory bodies.

Quiet breathing in open areas is associated with two- to three-fold greater inhalation of atmospheric pollutants compared to the protected environment of our home or a health club. The toxic material in the air is drawn more deeply into the lungs as the effort of breathing increases with progressive exercise. Mouth breathing during exercise bypasses the scrubbing and filtration of the air inhaled through the nose. This increases exposure to pollutants by more than 10 times.

Young children, old people and those with chronic heart or lung disorders are most vulnerable to the adverse health effects of air pollution. Effects of air pollution are most catastrophic when there is air stagnation during cold temperatures. The latter favours fog formation, which prevents the pollutants from moving above the ground level. The most dramatic consequences of smog formation were witnessed in London as far back as in the winter of 1952. Four thousand people died within a period of two weeks because of dense smog, which was a result of sulfur dioxide emitted by burning coal and diesel.

Air quality in urban India

The quality of air in Delhi represents the most striking example of air pollution in Indian cities:

1) More than 7,00,000 tonne of carbon dioxide is released in the atmosphere over Delhi in one year.

2) Delhi has more than 15,000 registered industries with an unknown number of unregistered units, spread all over the city without concern for environmental safety. Many of these units release dangerous toxins in the atmosphere. Practically all of them function regardless of the permissible levels of emission or proper disposal methods.

3) Thermal power stations emit more than 180 tonne of fly ash and 70 tonne of sulfur dioxide along with huge quantities of soot every day. It is noteworthy that Indian coal contains 15 to 45 per cent ash, as compared to 3–5 per cent ash in European coal.

4) Delhi has the highest number of vehicles in the country; 22 vehicles per 100 persons, compared to 6 per 100 persons in Bombay and 15 vehicles per 100 persons in Ahmedabad. About one million vehicles ply on the roads of Delhi every day, exhausting nearly 1,730 tonne of pollutants in the air.

Other cities of the country are not far behind. The level of pollution is rising so steeply that it is affecting the flora, the fauna as well as buildings and monuments. The case of the Taj Mahal is a prime example of environmental degradation.

Air pollutants

The major air pollutants are:

1) Sulfur oxides and soot particles are produced by the burning of fossil fuel. These constitute what is known as reducing smog.

2) Carbon monoxide, nitrogen oxides and hydrocarbons released from automobiles. Atmospheric carbon monoxide and nitrogen oxides form oxidant smog. Their levels exceed the acceptable limits in Delhi. Studies conducted by the Central Pollution Control Board (CPCB) indicate that vehicular activities contribute to 70 per cent of the total nitrogen oxide emissions in Delhi. Two- and three-wheelers are the major sources of carbon monoxide. Hydrocarbons react with oxygen, in the presence of bright sunlight, to form ozone. High levels of ozone are especially likely to occur in downwind urban regions. Nitrogen oxides react with hydrocarbons in the presence of sunlight to form peroxyacylnitrate (PAN), a major toxin for human beings.

3) Industrial air pollutants like cadmium, mercury, beryllium, mercaptans, hydrogen sulphide, hydrogen fluoride, chlorine and asbestos. People living near industrial areas are especially prone to the adverse health effects of industrial pollutants.

Adverse health effects

1) Chronic exposure to reducing smog leads to frequent colds, cough and eye irritation. The risk of bronchial asthma and lung cancer may also increase.

2) Respiratory illness in early childhood is associated with chronic exposure to modestly elevated levels of sulfur dioxide and particulate matter. In susceptible individuals, sulfur oxides may cause spasm of the airways passages leading to breathing difficulty, even in acceptable concentrations. These are also known to paralyse airways cleansing mechanisms, which are so vital for removing unwanted secretions and infectious agents from the respiratory tract.

3) Inhalation of carbon monoxide causes impairment of oxygen transport in blood and retardation of higher mental functions. In coronary heart disease (CHD), carbon monoxide increases susceptibility to angina. Exercise in presence of high concentrations of carbon monoxide may lead to acute toxicity. Prolonged exposure at rest may produce similar adverse consequences.

4) Exposure to high concentrations of nitrogen peroxide may flood the lungs with water, which is a life-threatening condition.

5) Ozone may cause spasm of the airways passages in concentrations found in urban air. Besides, its cancer-causing effects are well known.

Recently, a possibility has been raised that arterial wall damage from free radicals generated in atmosphere as a result of air pollution may explain a much higher incidence of CHD in urban areas, when compared to rural areas. This is an attractive hypothesis, which needs further study.

When headed outdoors

While it is possible to control factors like ambient temperature and humidity in a closed space such as a health club, no such modification is possible in the open environment. Therefore, exercise in a controlled and regulated atmosphere is always safer. Yet, it is not possible for everyone to exercise indoors due to various reasons. The following precautions may be helpful during outdoor exercises:

1) Do not exercise in smog or foggy atmosphere.

2) Do not exercise near a busy road, high traffic intersections, bus terminals, railway stations or an industrial area during any time of the day.

3) Do not exercise outdoors in the open during traffic hours.

4) Always breathe through your nose. Avoid mouth breathing as it increases exposure to air pollutants.

The writer is Director Cardiology and Head, Department of Preventive and Rehabilitative Cardiology, Fortis-Escorts Heart Institute, New Delhi