Filters in air conditioners gather dust, minute particles and airborne pollutants, while circulating cool air in a closed area. If a swine flu infected person coughs or sneezes in an air-conditioned room, the virus may travel up to the filters and settle down there.

“The virus in the filter then starts circulating along with cool air,” Dr P Guhanatham, Chennai Corporation Health Officer, said.

Some of the other precautionary measures are frequent gargling with warm salt water and washing hands and nostrils regularly.

Besides the pamphlet, the Corporation has come up with posters to spread awareness about containing the disease.

Allaying fears of swine flu, Guhanathan said the situation was not as alarming as reported in the media.

According to him, out of 10,000 people tested for H1N1 virus in the last two days by the Corporation officials, only one had shown symptoms of the disease.

He said: “Even people with violent coughing, sneezing or running nose can move around in public places like cinema halls, hospitals, trains and buses with a mask.”