A major drug maker in Northeast China stands accused of seriously polluting its environs and of violating regulations that set limits on discharges of pollutants, CCTV, the State broadcaster, reported on Sunday.

The report said the pharmaceutical factory has not done enough since 2004 to eliminate the causes of its pollutant discharges during production.

The discharges have lent a bad odor to the environs of the General Pharmaceutical Factory of Harbin Pharmaceutical Group Co Ltd, which is based in Harbin, capital of Northeast China's Heilongjiang province.

The smell is so bad that residents living nearby have taken to wearing masks and closing the windows of their homes, CCTV showed in its report.

Some residents said their exposure to the stench had caused them to contract tracheitis, an infection of the windpipe.

CCTV said the foul air has been traced to the sections of the factory where penicillin is produced through fermentation and drying. Hydrogen sulfide, a toxic gas, is also emitted into the air when wastewater is treated at the factory.

The company's official website says the factory, measured by its output, is one of the biggest producers of penicillin and other antibiotics in China.

Independent tests have found that the amount of hydrogen sulfide in the air near the factory is 1,550 times higher than the limit allowed by national regulations and the amount of ammonia gas is about 20 times higher, according to Tian Jiawei, professor with the No 2 Hospital of the Harbin Medial University.

In July 2009, the Harbin environmental protection bureau confirmed in a statement that the factory was to blame for the foul smell.

The bureau could not be reached for comment on Monday, which was a national holiday.

The bureau has been receiving a large number of complaints about stinky air since June 2007.

Investigations found that the factory continued to emit gas despite earlier attempts at curtailing discharges of pollutants, the statement said.

In addition, CCTV found that the factory was discharging wastewater into a small river flowing outside the factory. A test conducted on a sample of the wastewater showed it contained a nitrogen compound in an amount that was more than double the legal limit.

In its report, CCTV interviewed an unnamed factory employee in charge of monitoring the sewage outfall at the factory. He said part of the factory's wastewater treatment plant had ceased operating for more than a month to undergo maintenance.

Meanwhile, another section of the factory was found to be burning solid waste and then dumping it into the same small river, CCTV's report showed.