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Air Pollution Can Aggravate Asthma
Dr Pradyut Waghray
Studies on the effect of air pollution on asthma have come up with conclusive evidence to show that air pollution does worsen asthma, although it may not initiate the disease.

One of the earliest such studies was conducted in the 1950s when the smog in London was blamed for the rise in wheeze and cough among the residents. In India, studies were conducted in cities to compare Lung Function Test results of two sets of people. One set of people included residents of apartments with windows facing traffic junctions, while another set was those who stayed in flats away from the main roads. The people who stayed close to traffic signals showed higher reduction in lung capacity.

Earlier, sulphur dioxide and the burning of coal were listed as the major pollutants, but the new additions to that list are deadlier. These are photochemicals caused by the combustion of petrol and diesel.

City traffic is often congested, and high emissions of exhaust smoke from vehicles using diesel and petrol only add to the pollution. Nitrogen dioxide, ozone and a certain particulate material are the three main culprits causing atmospheric pollution.

The main pollutants from vehicular traffic and outdoor air pollution are:

Ozone levels: Ozone is produced when pollution from vehicles reacts with oxygen and sunlight. Ozone triggers a toxic component of smog that can exacerbate asthma.
It is important here to differentiate between the protective ozone in the upper atmosphere and the harmful ozone in the lower atmosphere.

Nitrogen oxide: This is a gas that is emitted from exhaust pipes and power plants. Besides contributing to the formation of ground level ozone and smog, nitrogen oxide also reacts with other air pollutants to form small particles that can cause breathing difficulties in asthma patients.

Sulphur dioxide: This is produced when coal and crude oil are burned and is an irritant associated with the onset of asthma attacks. Oil refineries and diesel engines that burn high sulphur fuel release large amount of sulphur dioxide into the air.

Air particles: A wide range of air particles found in dust, wood smoke, diesel exhaust particles and soot can trigger asthma.

Of the air particles, a certain particulate matter called PM10 (particulate matter with a mass median aerodynamic diameter less than 10 microm) is potentially very damaging. These particles are so small that when inhaled, they can penetrate deep inside the lungs, and deposit themselves in the smaller airways and lung parenchyma.

High levels of air pollution can cause decreased lung function and more frequent respiratory problems. And this certainly worsens asthma.

One must take adequate precautions and avoid undue exposure to traffic pollution. Using helmets when driving two-wheeler can not only offer protection against potential brain damage in the event of an accident, but also help keep at bay asthma triggered from traffic pollution.
Four-wheeler riders must avoid open-topped vehicles and avoid driving through heavily congested roads with the window panes down. On the whole, it is important for asthmatics to avoid vehicular pollution in order not to trigger an asthmatic attack.
Dr Pradyut Waghray, Consultant Chest Physician, Critical Care and Sleep Medicine Specialist, Senior Consultant Pulmonologist, Apollo Health City, Hyderabad.

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