Air pollution in the North will ease from Friday to Monday due to rain, while over 2.4 million people in Thailand have been diagnosed with health problems associated with smog, according to the Public Health Ministry.
Dr Opas Karnkawinpong, the public health permanent secretary, on Wednesday said PM2.5 levels recorded in the North ranged between 48 and 234 microgrammes per cubic metre (µg/m³).
Chiang Mai had the most hotspots with 279, Chiang Rai, 215 and Nan, 115.
Eight provinces were measured as having more than 51 µg/m³ over the past three days.
They were Muang and Chalerm Prakiat districts in Nan; Muang, Chiang Dao and Mae Chaem districts in Chiang Mai; Muang, Mae Sai and Chiang Khong districts in Chiang Rai; Muang district in Phrae; Muang district in Phayao; Muang and Li districts in Lamphun; Muang and Mae Mo districts in Lampang; Muang, Mae Sariang and Pai districts in Mae Hong Son.
It was forecast that weather conditions in Bangkok and its adjacent provinces will improve until Monday -- allowing for wind-assisted dust removal from the area.
However, 17 northern provinces, especially Chiang Rai and Nan, need to be closely monitored. The situation began improving on Wednesday due to increased wind speeds in the upper region, which rainfall expected in some parts of the north from tomorrow until Monday.
If PM2.5 levels are detected at more than 150 µg/m³, these areas will be designated as red zones and village heads will be alerted four times a day -- at 7am, 12pm, 3pm and 6pm, Dr Opas said.
Tambon health promotion hospitals will deploy health teams to provide initial healthcare and an online clinic.
Dr Opas said three village health volunteer teams have been deployed. Medical supplies such as 122,000 N95 masks were sent to Area Health 1 and 50,000 more to Area Health 2. The cumulative number of patients affected by air pollution is 2.47 million cases, with 184,465 additional cases recorded last week, he said.
Many suffered respiratory diseases, while others complained of dermatitis and eye diseases. Most patients have nose irritation (34.23%), coughing (24.32%) and eye irritation (20.72%), Dr Opas said.
An air quality check on Wednesday showed PM2.5 levels beyond the 50 µg/m³ threshold in 30 provinces. Air pollution in the North ranged between 43 and 211 µg/m³, and Bangkok and its adjacent provinces ranged between 33 and 66 µg/m³.