Thananchai Wannasuk, director of Regional Environmental Office 16 based in Songkhla, said if the two provinces’ readings showed 91mcg or above, the provincial authorities would close schools as per the Paediatric Society of Thailand’s recommendation, because such high levels of the tiny particle dust could affect children as well as pregnant women more severely.

The Pollution Control Department said Tambon Sateng in Yala’s Muang district registered 88mcg as of 9am on Tuesday, while Tambon Bang Nak in Narathiwat’s Muang district experienced 77mcg.

Pattani’s Muang district, Songkhla’s Hat Yai, Satun’s Muang district, Trang’s Muang district and Phuket’s Muang district also reported unsafe air levels of 58mcg, 69mcg, 64mcg, 52mcg and 52mcg, respectively.

Two other southern provinces – Phatthalung (at 49mcg) and Nakhon Si Thammarat (39mcg) – were also placed on watch, he added.