Chiang Mai, Bangkok choking near top of world air pollution rankings

Chiang Mai has regularly topped the rankings over the past few weeks, though Chiang Rai, which is not included in the list, has registered even higher scores on the IQAir scale.

Chiang Rai registered an air quality index of 199 on Tuesday, compared with 177 for Chiang Mai and 157 for Bangkok.

The scale has six categories: 0-50 (good air quality), 51-100 (intermediate), 101-150 (unhealthy for some groups), 151-200 (unhealthy), 201-300 (very unhealthy), and over 301 (hazardous).

The 10 cities with the worst air pollution in the world as of 10am according to IQAir were:

1. Kathmandu, Nepal – 186

2. Chiang Mai – 177

3. Dhaka, Bangladesh – 164

4. Bangkok – 157

5. Johannesburg, South Africa – 154

6. Kolkata, India – 153

7. Shenyang, China – 151

8. Kuching, Malaysia – 142

9. Yangon, Myanmar – 142

10. Delhi, India – 133

Meanwhile, levels of hazardous PM2.5 air pollution averaged 67.3 micrograms per cubic metre (mcg) in Bangkok, 98.1 in Chiang Mai, and 117.8 in Chiang Rai, according to IQAir.

Thailand’s safe limit for PM2.5 – fine-dust pollution linked with early death from heart and/or lung conditions – is 50mcg.

According to the Pollution Control Department, Chiang Mai’s highest PM2.5 level was in Chiang Dao district with 134mcg, followed by Muang district (102mcg), Mae Chaem (76mcg) and Hot (56mcg).

Meanwhile, 29 air-quality monitoring stations across Bangkok reported high levels of PM2.5 pollution as of 7am.

PM2.5 readings were between 38 and 58mcg in most parts of the capital, according to Bangkok Air Quality Centre.

The top 10 most polluted areas in Bangkok as of 7am on Monday were:

1. Bueng Kum district office (92mcg)

2. Thonburi Railway Police Station, Bangkok Noi (58)

3. Khlong Toei district office (58)

4. Bang Khen district office (58)

5. Taksin Bridge, Khlong San (58)

6. Samyan Mitrtown, Patum Wan (58)

7. Thonburi Market (Sanam Luang 2), Thawee Watthana (57)

8. Phra Nakhon district office (57)

9. Big C shopping mall, Bang Na (57)

10. Bang Phlat district office (57)

People living in areas suffering high air pollution are advised to reduce time spent outdoors and use protective gear such as face masks. Those who develop a cough, difficulty breathing, eye irritation, headache, irregular heartbeat, nausea or exhaustion should consult a doctor.