A fleet of drones, trucks and small planes sprayed water to try to reduce air pollution around Bangkok on Thursday while the governor invited critics to brainstorm better ideas to improve the air quality in the Thai capital.

Unhealthy pollution levels forced city schools to close Wednesday for the rest of week, and the Public Health Ministry advised against outdoor activities.

Faced with public discontent as well as a possible health crisis, the city’s governor has declared the city a «pollution control zone,» allowing firmer measures such as road closings and limits on diesel exhaust, outdoor burning and construction activities.

Prime Minister Prayuth Chan-ocha ordered inspections of factories to measure the pollution they are emitting.

The governor, Police Gen. Asawin Kwanmuang, said drones aren’t a long-term solution but he thinks every bit of effort helps. At a news conference, he said critics calling the drones a meaningless stunt would otherwise criticize him for doing nothing.

Asawin invited private-sector experts and academics to share ideas to improve air quality.

«Those who are knowledgeable on this issue, don’t give opinions to others, tell me. I am the one who is working on the issue, please give me advice,» he said. «Do I know everything? No, I don’t. Because I do not know everything, that’s why I will hold a meeting (Thursday). Please join us in brainstorming.»

Critics say the authorities’ attempt to combat pollution by using drones to spray water is ineffective.

The director of Greenpeace Thailand, Tara Buakumsri, said at best, the attempt will have a psychological impact on city dwellers, but it won’t improve air quality. Tara said the government should determine the sources of the pollution and come up with long-term strategies to reduce emissions from those sources.