A high level of styrene, a synthetic chemical used extensively in the manufacture of plastics, has been found in a 1km radius of the Ming Dih Chemical Company in Samut Prakan province, where a huge explosion occurred yesterday (Monday) morning, leading to a fire that took more than a day to extinguish. Returning to the site is not yet recommended, according to the Pollution Control Department.

The level of styrene found within the 1km radius is 1,035.47ppm, which is close to the level of 1,100 ppm which can have serious health impacts. Within a 3km radius, the styrene level is at 86.43ppm and at 51.77ppm in a 5km radius – both considered low enough not to impact health.

According to Assoc. Prof. Weerachai Phutdhawong of Kasetsart University, the chemicals found in the black smoke, which spread over several areas, are hazardous and can cause cancer. He urged the use of N95 masks that can filter PM2.5 and the avoidance of areas where chemical odours are distinct.

Seven evacuation sites have been opened, with more than 1,000 people taking refuge.

Meanwhile, the factory manager has admitted to police that the factory stores 1,600 tons of styrene monomer and that there had been a chemical leak.

The meteorological department has also issued a caution against the use of rain water over the next few days.

The Disease Control Department is conducting health checks on firefighters and those living in the proximity of the factory today and tomorrow, saying that inhaling the burned styrene monomer can cause irritation of the respiratory epithelium, headache, dizziness, fatigue and nausea.

According to Department Director-General Opart Karnkawinpong, styrene monomer is a transparent liquid with a unique odour. Other gasses produced from the burned styrene monomer besides styrene are carbon dioxide, carbon monoxide and benzene.