The Chiang Mai Administrative Court ruled on Friday (19 January) that the Prime Minister and the National Environment Board must complete a management plan to address local air pollution issues in 90 days.

Chiang Mai city on 6 April 2023, with the air pollution turning the sky brown.

The Court ruled that the Prime Minister and the National Environment Board (NEB) were either negligent or did not act in a timely manner to address air pollution in the northern provinces. It ruled that, because the northern provinces routinely experience severe air pollution levels between December – April of each year, the defendants must exercise their authority under the Enhancement and Conservation of National Environment Quality Act to prevent or relieve the damages caused by air pollution. It ordered that an integrated and sustainable emergency plan to prevent and relieve the damages caused by a high level of air pollution be completed within 90 days.

Academics, activists, medical professionals, and residents in Chiang Mai filed a class action lawsuit in April 2023 against then-Prime Minister Gen Prayut Chan-o-cha, the NEB, the Securities and Exchange Commission (SEC), and the Capital Market Supervisory Board (CMSB) for not taking action to solve air pollution in the north of Thailand.

The lawsuit alleged that the government had done little to address deteriorating air quality and demanded that the Prime Minister use his authority under Section 9 of the Enhancement and Conservation of the National Environmental Quality Act to order relevant agencies to alleviate the problem.

As the the problem remains severe, the plaintiffs  also demanded that the NEB follow the national action plan on air pollution declared in 2019.

Somchai Preechasilpakul, lecturer at Chiang Mai University's Faculty of Law and one of the plaintiffs, explained in a May 2023 press conference that the lawsuit is filed against the Prime Minister and not Gen Prayut as an individual. Anyone who become Prime Minister while the lawsuit is ongoing will therefore be responsible for taking any action ordered by the Court.

The group sued the SEC and the CMSB, responsible for extraterritorial obligations, to make them compell companies to disclose pollution information on their 56-1 One Report form. The hope was to make information available on the origin of air pollutants, both domestically and in neighbouring countries.  

However, the Chiang Mai Administrative Court dismissed these latter two lawsuits on the grounds that the two agencies were not responsible for air pollution, directly or through administrative negligence.

Kornkanok Wattanaphum, a lawyer for the residents, explained after their appeal was rejected on 5 January 2024 that the plaintiffs were suing the SEC and CMSB because the air pollution problem in the north of Thailand cannot be solved with one legislation alone, since agricultural businesses and coal power plant are also involved in trans-border air pollution issue. The plaintiffs believe that the SEC and CMSB could play a crucial role in disclosing information and regulating businesses in terms of human rights and environmental impact.