Toxic haze sends PM2.5 soaring to ‘extremely dangerous’ levels in Chiang Mai

CHIANG MAI, April 4 — Northern Thailand is once again under a blanket of toxic haze, with Chiang Mai facing one of its worst air pollution episodes in recent months as fine particulate levels surged to “extremely dangerous” levels, according to The Nation.

PM2.5 concentrations at Nakornping Hospital in Mae Rim district hit 409 micrograms per cubic metre at about 9am today — a level far exceeding safe limits and considered hazardous to human health.

Images from the area showed thick smog engulfing the city, reducing visibility so severely that nearby buildings were barely discernible.

Health officials warned the crisis is already affecting patients, particularly those in vulnerable groups, with many reporting breathing difficulties as the haze intensified through the day.

Authorities have urged residents to take immediate precautions, including avoiding outdoor activity altogether.

“Exercise or prolonged exposure in open areas… could significantly increase the amount of fine particulate matter inhaled into the lungs,” officials said.

Those who must go outside have been strongly advised to wear properly fitted N95 masks, as standard surgical masks are not effective in filtering PM2.5 particles.

Residents have also been told to create “safe zones” indoors by sealing windows and using air purifiers to reduce indoor pollution levels.

Anyone experiencing symptoms such as coughing, chest tightness, eye irritation or difficulty breathing is advised to seek medical attention immediately.

People with underlying conditions — including heart and respiratory diseases — are considered at highest risk and are urged to remain indoors in protected environments.

The worsening conditions underscore a recurring challenge for northern Thailand, where seasonal haze continues to pose serious public health risks.

Officials stressed that the current episode is not just an environmental issue but a long-term threat to quality of life, warning that sustained and coordinated solutions are needed beyond short-term measures.