Nita Bhalla, New Delhi: Dangerously high levels of mercury have been found in the air in two Indian hospitals which could seriously threaten the health of patients and medical staff, a study by an environmental group said on Wednesday.

Air samples tested by New Delhi-based Toxics Link in the large private hospitals in the Indian capital found that levels of the heavy metal were on average almost seven times higher than recommended levels.

Mercury, sometimes called quicksilver, is highly toxic and exposure can damage the brain, nervous system and foetuses. "The mercury present in the air in hospitals comes mainly from the breakage of thermometers and because the mercury is not disposed of in the proper manner, it vaporises into the air," Ravi Agarwal, director of Toxics Link, told a news conference.

Only two hospitals were surveyed as researchers were denied permission to other hospitals, including government-run ones, said Agarwal. Toxics Link said it believed mercury levels would be similar in other private hospitals and higher in state-run centres.

Past research done by the organisation and other groups indicated around 700 thermometers break every month in hospitals with 300 to 500 beds. In one of the hospitals surveyed, mercury levels averaged 2.8 micrograms per cubic metre.

The U.S. Environmental Protection Agency recommends levels no higher than 0.3. At present, India has no standards for mercury levels in indoor ambient air or laws to regulate its use in hospitals.

Many private hospitals were trying to implement mercury management programmes and introduce digital thermometers, but most government hospitals were yet to act, Agarwal said.

There was no immediate comment from the government. Mercury, also used in batteries, fluorescent lamps, industrial chemicals and paints, is mainly imported from Europe, which aims to phase out its usage by 2011.

India imported about 2,290 tonnes of mercury from 1996 to 2004, making it the second largest consumer in the world after China.