A fire broke out Monday at a residue desulfurization unit operated by state-controlled oil refiner CPC Corp., Taiwan's (CPC's) factory in Kaohsiung, but there were no casualties, the city's Environmental Protection Bureau said.

A preliminary report indicated that there were emissions of hydrogen gas from the plant after the fire broke out, the bureau said. It said the fire was caused by a fracture in a pipe in the factory's residue desulfurization unit II.

Following the incident, the bureau discovered large amounts of gaseous air pollutants near the factory and fined the refinery NT$1 million (US$33,490) for polluting the air, the highest amount possible for a violation under the Air Pollution Control Act.

Local residents reported that they heard explosions and smelled a pungent odor coming from the factory.

The fire started around 12:33 p.m. and was extinguished at about 1:05 p.m. by a team of 52 firefighters and 22 fire trucks dispatched by the city's fire department. Operations at CPC's refinery in Kaohsiung have been suspended pending an investigation by the city's fire department and labor affairs department.

The Environmental Protection Bureau said it will continue to monitor the plant's manufacturing process and has collected gas emissions for odor detection.

After the accident, an air-quality monitor at the site showed a concentration of 267 micrograms per cubic meter of particulate matter and 164.5 ppb (parts per billion) of sulfur dioxide, compared with averages of 30 micrograms per cubic meter and 5 ppb recorded in other parts of the city.

Readings of particulate contamination above 250 over a 24-hour stretch are considered hazardous.