Air pollution in the Thai capital forced the closure of more than 350 schools on Friday, city authorities said, the highest number in five years. Bangkok officials announced free public transport for a week in a bid to reduce traffic in a city notorious for noxious exhaust fumes.

Air pollution has led to the closure of over 350 schools in Bangkok, as the city ranked seventh in the world for pollution. Levels of harmful PM2.5 pollutants were significantly above WHO guidelines.

Air pollution in the Thai capital has forced the closure of more than 350 schools, city authorities said, as Bangkok was ranked the world’s seventh-most polluted major city by air quality monitor IQAir.