Thailand Prime Minister Srettha Thavisin has refused to label Chiang Mai as a disaster zone after the city became the world's most polluted city on March 18 according to IQAir with an Air Quality Index of 172.

Footage shows a blanket of smog shrouding the city.

Thavisin has defended his decision by claiming he was trying to protect the area's tourism industry.

Today looking west towards Doi Suthep National Park, the forests are invisible. Looking east from Doi Suthep NP, Chiang Mai City is mostly invisible.
According to IQAir,as at 15.30 local time on March 18, the Air Quality Index for PM 2.5 particles was the world's worst at 182. In the last 5 days it has also been the world's worst on 3 days, unhealthy or very unhealthy.
According to WHO guidelines the 24 hour recommendation for PM 2.5 is 15, therefore today's pollution exceeds that by 12 fold.
It's an annual occurrence blamed on farmers burning crops and neighbouring countries doing likewise.
As the dry season continues, trees are drying and the situation is predicted to continue, despite robust fire-fighting efforts. Two million masks have been distributed to locals.