
A wildfire at Khao Chom Hae in Rayong has persisted for more than five days, leading to growing worries about heightened dust pollution in the eastern Thai province and beyond.
The fire has spread to over 20,000 rai (7,900 acres) across the three districts of Nikhom Phatthana, Ban Chang and Muang, with about 30% of the forest already burned.
Firefighting efforts are hampered by challenging terrain, requiring local teams to hike up steep slopes to establish firebreaks.
Volunteer driver Kittipong Bamrungphong, 57, said that while off-road vehicles are used to transport firefighters, they still face hikes to reach the blaze.
Strong winds are also complicating containment efforts, raising concerns for nearby homes. Residents are urging the deployment of helicopters for assistance.
The wildfire has caused an increase in fine particulate matter smaller than 2.5 microns (PM2.5) in Rayong, leading to respiratory issues among people, who are advised to wear masks and limit outdoor activities.
As of 4pm Saturday, the 24-hour average PM2.5 reading in Rayong was 80 microgrammes per cubic metre of air (µg/m³), according to the Geo-Informatics and Space Technology Development Agency (Gistda). Any reading above 37.5µg/m³ is considered unhealthy. (Story continues below)

A wildfire burns at Khao Chom Hae in Rayong province on Saturday. (Photo: Ban Chang Facebook)
Meanwhile, Kasikorn Research Centre (KResearch) has estimated that worsening air pollution in Bangkok has cost the economy at least 3 billion baht this month.
The figure includes medical expenses for respiratory illnesses, costs for protective masks and air purifiers. While these expenses benefit some businesses, they represent an economic opportunity cost since this money cannot be spent elsewhere.
KResearch added that long-term consequences like chronic health risks, mental health issues and implications for the country’s image as a business and tourism hub remain difficult to quantify.
As of 4pm Saturday, 40 out of the 50 districts in Bangkok were red zones, with PM2.5 readings of 75µg/m³ or more — twice the maximum level considered safe, according to Gistda.
Authorities on Saturday began offering free public transport in Bangkok for one week, in hopes of reducing the use of private vehicles and cutting down emissions.
Free rides are available on all public buses and electric rail lines in the capital. The cost to taxpayers of reimbursing the operators has been estimated at 140 million baht.