Air quality in Thailand’s capital Bangkok and Laos’ capital Vientiane deteriorated to hazardous levels this week, prompting authorities and monitoring groups to warn residents to limit outdoor activity as fine particulate pollution rose well above health standards.
In Bangkok, the average concentration of particulate matter smaller than 2.5 micrometres (PM2.5) reached 58.1 micrograms per cubic metre on Wednesday morning, exceeding the national standard of 37.5 micrograms, according to the Bangkok Air Quality Information Centre. Officials classified conditions as “orange”, indicating air quality was beginning to affect health.
The worst-hit districts included Bang Rak, which recorded PM2.5 levels of 86.9 micrograms per cubic metre, followed by Pathum Wan at 83.4 and Sathorn at 78.5. Other central and northern districts, including Chatuchak and Ratchathewi, also reported elevated readings.
Seasonal haze linked to pollutant trapping, vehicle emissions and agricultural burning has been documented in the region and associated with spikes in respiratory and cardiovascular conditions.
Studies show that fine particulate pollution is linked to increased risk of heart disease, strokes, lung cancer and chronic respiratory illnesses, and children and vulnerable populations are especially at risk from short- and long-term exposure.
Authorities urged residents to wear PM2.5 masks outdoors, limit strenuous activity and watch for symptoms such as coughing, breathing difficulty or eye irritation. Vulnerable groups, including those with pre-existing medical conditions, were advised to avoid outdoor exposure where possible.
Thailand’s Department of Royal Rainmaking and Agricultural Aviation (DRRAA) said it had launched emergency flights to help disperse PM2.5 particles. The operation involves aircraft from multiple air bases using cloud-seeding and dry ice techniques to break up and disperse fine dust.
Four aircraft from the Hua Hin base, for instance, were deployed to Ratchaburi and Samut Songkhram on 14 January, using dry ice seeding at altitudes above 2,000 metres to disperse dust.
Across the Mekong River in Laos, air quality in Vientiane reached hazardous territory on Friday, with monitoring group IQAir reporting an air quality index AQI+ reading of 203 as of 08:35 local time. An AQI above 200 is typically considered “very unhealthy” to “hazardous” under international air quality guidelines.
Other Laotian cities also recorded poor conditions, with Luang Prabang posting an AQI of 152 and Pakse at 126, IQAir data showed.
Regional air pollution often worsens during the dry season, when agricultural burning, vehicle emissions and stagnant weather conditions combine to trap fine particles over urban and rural areas, affecting millions across mainland Southeast Asia.
Recent research indicates that PM2.5 exposure has been a major contributor to mortality across Asia over recent decades, linked to millions of premature deaths and a broad range of health issues, underscoring the urgency of stronger air quality controls in the region.
Governments across the region have stepped up short-term emergency measures and longer-term policy responses. In Thailand, authorities have tightened restrictions on open burning, expanded inspections of industrial facilities and construction sites, and promoted work-from-home arrangements during severe pollution episodes.
The transport ministry has also encouraged the use of public transport and electric vehicles to curb traffic-related emissions, while the health ministry has increased public advisories and hospital preparedness during peak haze periods.
In Laos, officials have previously issued public health warnings and urged schools and local administrations to limit outdoor activities when air quality reaches hazardous levels, particularly for children, the elderly and those with respiratory conditions.
Regional bodies and environmental groups have also renewed calls for greater cross-border cooperation, noting that transboundary haze from agricultural fires and forest clearing can spread pollution across national boundaries, complicating enforcement and mitigation efforts.
Despite these measures, analysts and public health experts say structural challenges, including reliance on biomass burning, rapid urbanisation and limited air quality monitoring and enforcement capacity in parts of the region, continue to hamper sustained improvements, raising concerns that severe haze episodes could become more frequent as climate change intensifies dry season conditions.
