Contents
Hanoi averaged 45.9 µg/m³ of PM2.5 in 2025, over 9 times the WHO guideline. How Bangkok, Kuala Lumpur, Singapore and Australia compare for children.
According to IQAir's 2025 World Air Quality Report, Hanoi averaged 45.9 µg/m³ of fine particulate matter (PM2.5) in 2025 – more than 9 times the World Health Organization's annual guideline of 5 µg/m³. Ho Chi Minh City came in at 21.5 µg/m³, Bangkok at 17.6, Kuala Lumpur at 15.7 and Singapore at 11.9. Australia was one of the few countries to meet the WHO guideline, at 4.4 µg/m³. The WHO warns that in children, air pollution can stunt lung growth, cause respiratory infections and worsen asthma. For families with young children, air quality belongs on the table when weighing schools and a long-term home.
Source: IQAir, World Air Quality Report 2025; HEI and UNICEF, State of Global Air 2024
When a Vietnamese family considers sending a child to school abroad or setting up a second home, the first questions are usually tuition, school quality and residence paperwork. The air a child breathes every day rarely makes it onto the comparison sheet – even though it's measurable, publicly reported and changes only slowly from year to year.
This piece puts Hanoi and Ho Chi Minh City next to the cities Vietnamese investors most often mention, from Bangkok, Kuala Lumpur and Singapore to Athens, Dubai and Australia. We also flag where the data is solid and where it deserves a second look.
Where Hanoi Sits on the Particulate Map
IQAir, the Swiss air-quality technology company, compiled its 2025 report from 9,446 cities in 143 countries and territories. As Health Policy Watch reported, only 14% of cities met the WHO annual guideline, down from 17% a year earlier. Just 13 countries and territories met it nationally, most of them in Latin America and the Caribbean.
Hanoi ranks 112th in IQAir's city table. Most of the places above it are in South Asia and China. New Delhi remains the world's most polluted capital at 99.6 µg/m³, while Loni, in India's Uttar Pradesh state, tops the city ranking at 112.5 µg/m³. Against the Asian cities Vietnamese families often consider for schooling, Hanoi's level is close to three times Kuala Lumpur's and double Ho Chi Minh City's.
Ho Chi Minh City is much lower – but still more than 4 times the WHO guideline. Dubai – in the UAE, the country that has drawn the most relocating millionaires in recent years – sits at 35.8 µg/m³. Clean air, in other words, is its own criterion. It doesn't automatically come with a city's wealth or modernity.
Nine Years of Data, and Hanoi Has Not Dropped Below 36
IQAir's record for Hanoi goes back to 2017. Over those nine years, the lowest annual average was 36.2 µg/m³ in 2021 and the highest 46.9 µg/m³ in 2019. Since 2021 the figure has risen four years in a row, reaching 45.9 µg/m³ in 2025.
Clean air is its own criterion. It doesn't automatically come with a city's wealth or modernity.
The seasonal rhythm matters as much as the average. Viet Nam News, citing the previous IQAir report, noted that Hanoi did not record a single month of good air quality in 2024, and that March, April, October, November and December were the worst. Those months fall squarely within the school year.
View data table
| Item | Value |
|---|---|
| 2017 | 45.8 µg/m³ |
| 2018 | 40.8 µg/m³ |
| 2019 | 46.9 µg/m³ |
| 2020 | 37.9 µg/m³ |
| 2021 | 36.2 µg/m³ |
| 2022 | 40.1 µg/m³ |
| 2023 | 43.7 µg/m³ |
| 2024 | 45.4 µg/m³ |
| 2025 | 45.9 µg/m³ |
Source: IQAir, city ranking 2017–2025
Ho Chi Minh City has moved sideways around 21 µg/m³. Over the same period its annual figure ranged from 19.4 to 26.9 µg/m³, and since 2020 it has barely moved, staying between 19.4 and 22. Vietnam's two biggest cities therefore pose two quite different questions for families with young children.
Neighbouring Cities Have Cut Their Particulates
Compared with 2019, most cities in our comparison set now breathe cleaner air. Athens is down 7.6 µg/m³, Seoul 6.9, Kuala Lumpur 5.9 and Bangkok 5.2. Hanoi is down just 1.0 µg/m³ against 2019 – which was its highest year on record.
Progress isn't smooth. Bangkok is the clearest example: its annual average fell from 27.6 µg/m³ in 2017 to 17.6 µg/m³ in 2025, yet in January 2025 more than 350 Bangkok schools still had to close when particulate levels spiked, Al Jazeera reported. An annual average tells you the trend. It doesn't tell you what a January morning at your child's school will feel like.
Why Children Bear the Heaviest Cost
According to State of Global Air 2024, produced by the Health Effects Institute (HEI) with UNICEF, air pollution was linked to 8.1 million deaths worldwide in 2021. More than 700,000 of them were children under five – 15% of all deaths in that age group. Air pollution is the second-largest risk factor for death overall, including for young children.
An annual average tells you the trend. It doesn't tell you what a January morning at your child's school will feel like.
For urban families, the main concern is outdoor particulates. The WHO-air-quality-and-health) estimates that outdoor air pollution caused 4.2 million premature deaths in 2019, 89% of them in low- and middle-income countries, at a time when 99% of the world's population lived in places that did not meet its guideline levels. When the WHO tightened its PM2.5 guideline in 2021, it spelled out the effects on children: reduced lung growth and function, respiratory infections and aggravated asthma.
The exposure adds up over the years. A child who spends the first ten years of life at 45 µg/m³ breathes in a very different dose of fine particles from a classmate living at 5 µg/m³. The gap between those two numbers is real, and it runs through the years when a child's lungs are still growing.
Lining Up the Destinations Country by Country
National averages help compare places where city-level data is thin. On IQAir's figures, Vietnam ranked 18th most polluted of 143 countries in 2025, at 29.7 µg/m³. Australia and Portugal sit near the bottom of the table – in other words, among the cleanest.
Greece also gets Saharan dust. Health Policy Watch noted that Greece and Switzerland had smog days linked to dust blown in from the Sahara in 2025. It's a reminder that not every particle comes from traffic or factories – and that some sources are beyond any city's control.
Reading the Numbers With a Clear Head
IQAir's data comes from roughly 50,000 monitors and low-cost sensors, which left about 33,000 data points after cleaning. Monitoring weakened in 44 countries in 2025, and six had no data at all. When two cities sit close together – Kuala Lumpur and Hong Kong both recorded 15.7 µg/m³ – it's not enough to say which one is cleaner.
City averages also hide differences between districts. An international school next to a park and an apartment on a main road can be worlds apart. For Singapore, the 11.9 µg/m³ figure is the average for the whole city-state.
A practical strategy for Vietnamese investors
Add air quality to the school comparison. When choosing a school, look at the city's annual PM2.5 and its worst months alongside tuition and curriculum.
Consider places that already meet the WHO guideline. Australia was one of the few countries under 5 µg/m³ in 2025. A family with a child studying in Sydney might look at apartments near the Metro, such as Aura in North Sydney – a home for the student and a rental asset in one.
There are better options close to home, too. Kuala Lumpur's 2025 particulate level was about a third of Hanoi's, and it's a short flight from Vietnam. An apartment such as Pavilion Square in Bukit Bintang suits families who want an international education without going far.
Don't decide on one number. Air quality should sit alongside safety, healthcare and education. NAC's pieces on the Global Peace Index 2026 and on climate migration help complete the picture.
Frequently asked questions
What was Hanoi's PM2.5 level in 2025?
IQAir puts the annual average at 45.9 µg/m³ – more than 9 times the WHO guideline of 5 µg/m³, and slightly above 2024's 45.4 µg/m³.
Which Southeast Asian cities have cleaner air than Hanoi and Ho Chi Minh City?
In our comparison set, Bangkok (17.6), Kuala Lumpur (15.7) and Singapore (11.9 µg/m³, a nationwide figure) are all lower. None of them meets the WHO guideline.
Should a family move for air quality alone?
Not on one criterion. Air quality matters for a child's health, but it should be weighed with schooling, healthcare, cost and the whole family's residence plan.
NAC strategic insight
None of these numbers say every family in Hanoi should leave. They show that air quality is measurable, slow to change and has a lasting effect on young children – much like the quality of a school. For families planning an education abroad, it's data to put on the table at the start, not something to notice after arriving.
NAC helps Vietnamese families set data like this alongside residence programmes, schools and the right asset, so that every choice has a clear reason behind it. If you'd like to start from your child's education plan, book a consultation with NAC.
Sources
- Health Policy Watch — Air pollution worsens globally, share of cities meeting WHO guideline declines (2026)
- WHO — Ambient (outdoor) air pollution, fact sheet (2024)-air-quality-and-health)
- WHO — New WHO Global Air Quality Guidelines aim to save millions of lives (2021)
- HEI and UNICEF — State of Global Air 2024 (2024)
- Viet Nam News — Việt Nam's air quality 23rd worst in the world (2025)
- Al Jazeera — More than 350 schools close in Bangkok as air pollution soars (2025)
