Heavy smog shrouded a wide area of Asia in late January 2019, with health-threatening levels of pollution reported in India, South Korea, Thailand and China.
People in Seoul were urged to avoid outdoor activities as the South Korean capital experienced its worst air pollution in years.
In the Thai capital Bangkok, officials handed out face masks and sprayed water in an attempt to cleanse the air.
Devotees at the Hindu festival of Kumbh in northern India were choking on air particulate levels six times the level considered safe by the World Health Organisation (WHO).
Hong Kong hopes to control the problem in one busy traffic area with a new air-purification system. Among the world’s largest filters, the device designed to remove at least 80 per cent of air pollutants is set to go into service on January 20 as part of a new road bypass.