Urgent: PM2.5 set to worsen in Bangkok tonight as winds carry smoke from Nakhon Nayok

Bangkok residents have been warned that PM2.5 levels could rise sharply tonight, as surface winds push a large smoke-and-haze mass from Nakhon Nayok into the capital, adding to an ongoing air-pollution episode.

The Thai Meteorological Department (TMD) said it has detected a large concentration of smoke and haze over Nakhon Nayok that is moving towards eastern Bangkok. With Bangkok experiencing stagnant, “closed” atmospheric conditions, pollution is expected to disperse poorly, increasing the likelihood that PM2.5 will build up quickly during the night.

Why pollution is expected to intensify

Based on the latest satellite imagery dated 28 January 2026, multiple hotspots were detected in Nakhon Nayok. TMD and related reports said surface winds are carrying the resulting smoke directly towards Bangkok, with three key factors driving the increase:

• Wind direction: pollution is being transported from the east towards the city centre.
• Stagnant air: limited ventilation is trapping pollution closer to the ground, allowing it to accumulate.
• Peak window: the worst levels are expected from evening through the early hours.

What residents should do

TMD and related agencies advised residents to:

• Avoid outdoor activities, including exercise or outdoor work, where possible.
• Wear a suitable mask (such as an N95 or an equivalent PM2.5-rated mask) if going outdoors is unavoidable.
• Close doors and windows to reduce indoor infiltration of dust and smoke.
• Take extra care with vulnerable groups, including children, older people, pregnant women, and those with respiratory conditions.