ENVIRONMENTAL protection authorities have taken extra measures to monitor air quality in an area of the city's outskirts after a fire broke out at a small, unlicensed chemical plant yesterday.

The fire swept through the factory, which produced coating and painting products, about 11:20am in suburban Qingpu District's Zhaoxiang Town, police said.

Officials said as of late yesterday, they had taken extra air samples and had detected no toxic chemicals from the fire, in which no one was injured.

The fire heavily damaged the 400-square-meter factory and emitted black smoke that could be seen for kilometers. Fire officials said it took an hour to put out. The fire also damaged part of a building next door, according to a Shanghai Television report.

Residents in the area have complained in the past about smells coming from the factory, and yesterday they expressed concern that the smoke from the blaze may have been toxic, the report said.

Inflammable materials like xylene, a chemical commonly used as a solvent, were spotted at the plant, the television reported.

The district's environmental protection bureau told Shanghai Daily that the factory had no license. The owner of the illegal operation was in police custody pending further investigation.

Officials said yesterday that they still face challenges in supervising the production and transportation of chemicals, but there has been a decrease in accidents. In the first half of the year, a man was killed in an explosion at a chemical company in suburban Songjiang District.

This year, safety concerns have prompted the city to remove or relocate over 90 factories and firms producing or storing dangerous materials.