The Central Pollution Control Board's (CPCB) national air quality index bulletin has showed the air quality in Delhi as "severe", for three consecutive days. In circumstances like this, an emergency is usually declared in Beijing, and kindergartens and schools are closed down; industries are also temporarily shut down.

According to the World Health Organisation (WHO), the air in Delhi is one of the worst in terms of quality in the world. Apart from vehicular pollution, pollutants like nitrous oxide and sulfur dioxide that are present in the environment, cause the airways to get inflamed, and cause eye irritation and damage to the respiratory tract. As a result, the respiratory tract becomes prone to coughing, mucus secretion and long-term infections. The air is particularly damaging to those with asthma or weaker immune systems.

Poor air can also cause long-term problems. Dust particles from construction sites and poor quality air together can lead to reduced lung function and breathing problems as well as lung cancer or cardiovascular disease.

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Those with pre-existing cardiovascular or lung diseases are particularly vulnerable to the effects of pollution, and may find their conditions worsened due to exposure over a period of time.

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We got in touch with Dr Rakesh Gupta, Senior Consultant, Internal Medicine, Indraprastha Apollo Hospital, and asked him how this affects us and what we can do.

What are the health effects of air pollution?

Air pollution can affect your body from head to toe. The effects range from damaged hair, skin irritation, nasal blockage, asthma, watering from eyes, flu, bronchitis, conjunctivitis, cough etc.

Who are the most vulnerable?

Children and people who are already suffering from any chronic or pulmonary disease or those who have weak immunity, are the ones who are most vulnerable to air pollution.

Keeping in mind the poor air quality which is likely to further deteriorate in the coming years, many companies have come up with air purifiers. Why and who should buy them?

I would suggest it to people who really needs pure air around them, especially people with weaker immunity, which includes the elderly, children and patients suffering from chronic diseases. People who do breathing exercise can also buy them.

Are there any dietary changes we can make to better our immunity and therefore prevent the damage from poor air quality?

Food and diet will not alter the situation much, but you can build your immunity by taking proper nutrients, vitamin D and walking regularly. Quit smoking and avoid dust if possible. Small children and people with pre-existing diseases can wear a mask. Vaccinations for flu, swine flu, common cold, pneumonia are also available.