Air pollution in the greater Bangkok area was again threatening residents’ health on Sunday morning. The amount of PM2.5 – airborne dust particles 2.5 microns in diameter or less – exceeded the safe level of 50 micrograms per cubic metre of air along roads in 19 places. Bangkok’s Chatuchak district was choking on 96 micrograms per cubic metre and Nakhon Pathom’s Muang district 99. Saphan Kwai and Charoen Krung in Bangkok were also badly affected. The Pollution Control Department (PCD) was again working with other agencies to try and lower the PM2.5 level. The Bangkok Metropolitan Administration instructed district offices to clean roads every day and spray water in the air to curb dust. Operators of construction sites were told to prevent dust from spreading. The PCD was also in talks with the Royal Rainmaking and Agricultural Aviation Department about creating rain over the urban area. The World Health Organisation estimates that 7 million people die every year because of exposure to both outdoor and household air pollution. In 2013 it classified PM2.5 as a carcinogen, noting that the tiny particles easily enter the respiratory system and blood vessels to cause harm.