Air quality in Shanghai: AQI, purifiers, masks

Short answer: most days in Shanghai are fine, a few dozen a year aren't, and the gap between "fine for Shanghai" and "fine for Perth" is bigger than most Australians expect. A purifier at home and an app on your phone handle most of it.

The short version

In 2024, 88.5% of days in Shanghai were rated excellent or good under China's standard, and there were 42 polluted days [1].
Shanghai's annual PM2.5 average was about 28 µg/m³ in 2024, around 5.6 times the WHO annual guideline [1][3].
Winter brings PM2.5 smog; summer brings ozone. On polluted days in 2024, ozone was the main culprit more often than PM2.5 [1].
Chinese and US-style AQI apps use different scales, so the same air can show different numbers.
Run a HEPA purifier in bedrooms, keep a stash of well-fitted KN95 or FFP2 masks, and have an asthma plan if anyone in the family needs one.

How bad is it, really?

Shanghai's air has improved a lot in the last decade, and China as a whole recorded its best air on record in 2025, with an average PM2.5 of 28 µg/m³ across its prefecture-level cities and 89.3% good days [5]. Shanghai sits around that national average.

Here's what the city's own environment bulletin reported for 2024, the latest full year it has published in detail [1]:

Measure (Shanghai, 2024)	Result	What it means for you
Days rated excellent or good	88.5% (323 days)	Most days you won't think about it
Polluted days	42 (38 light, 3 moderate, 1 heavy)	About one day in nine needs some care
PM2.5 annual average	28 µg/m³	Meets China's national Grade II limit, well above WHO's guideline
PM10 annual average	43 µg/m³, down 10.4% on 2023	Coarser dust, less of a worry
Ozone (90th percentile, 8-hour max)	144 µg/m³, down 8.9%	The summer problem
NO₂ annual average	30 µg/m³	Traffic; worse beside elevated roads

The city government described 2024's PM2.5 as stable at a low level [2]. That's true by Chinese standards. By WHO standards, the annual guideline is 5 µg/m³, and Shanghai's 2024 figure was about 5.6 times that [3].

What Australians underestimate

Most Australian cities have clean air most of the year, and our big pollution memory is bushfire smoke. That's useful: you already know what a hazy day feels like. What's different in Shanghai is the background level. With an annual average several times the WHO guideline, even a day rated "good" in Shanghai can carry more fine particles than most Australians are used to breathing.

The WHO calls air pollution one of the greatest environmental risks to children's health, and fine particles are linked to heart disease, stroke, lung disease and lung cancer [4]. The risk builds over years, not days, which is why the daily habits matter more than panicking on the worst afternoon.

The seasons: winter smog, summer ozone

Shanghai's air has two different problems at different times of year.

Winter (roughly November to February). This is PM2.5 season. Cold, still, humid air traps particles near the ground, and much of the PM2.5 forms from nitrates in the air [3]. On 13 October 2025, an autumn episode pushed Shanghai's AQI to 158, ranking it among the most polluted major cities in the world that morning [3]. Rain and strong winds clear it out; stagnant, humid days let it build [3].

Summer (roughly May to September). The haze lifts, but ozone forms in strong sunlight. In 2024, ozone was the main pollutant on 22 of Shanghai's 42 polluted days, ahead of PM2.5 on 18 [1]. Ozone irritates airways and is worst in the afternoon. A purifier's HEPA filter doesn't remove it, so on high-ozone days the fix is timing: exercise early in the morning.

Spring and autumn are usually the best months, with episodes when the wind drops.

Reading the AQI without getting confused

The Air Quality Index turns pollutant levels into one number. Lower is better. The catch is that there are two common versions.

China's AQI is calculated under China's national standard. It's what official city monitors, weather apps and most Chinese apps show.
US-style AQI is used by many international apps and purifier brands. It rates fine particles more strictly, so the same air often shows a higher number.

Neither is wrong. Just stick with one app so you're comparing like with like, and look at the PM2.5 reading in µg/m³ as well as the index.

Rough AQI band	Label	What we'd do
0–50	Good	Open the windows, go for that run
51–100	Moderate	Normal life; sensitive people keep an eye on it
101–150	Unhealthy for sensitive groups	Kids and asthmatics cut long outdoor exercise; purifiers on
151–200	Unhealthy	Windows shut, masks outside, move training indoors
201 and up	Very unhealthy and worse	Stay in where you can; purifiers on high

Two tips. Check the forecast, not just the current number, because winter episodes often build over a couple of days. And check the pollutant: if it's ozone, a mask and purifier help less than changing the time of day.

Purifiers and masks

Choosing a purifier

You don't need the fanciest brand. You need the right size for the room and a real HEPA filter.

Measure the room. Bedrooms first, then the living area. Kids' rooms matter most because they spend 10 hours a night there.
Check the clean air delivery rate (CADR) for particles. A rough rule is to pick a unit rated for a bigger room than yours, so it can run quietly on a low setting.
Look for a true HEPA filter and, if you're near a busy road or have just renovated, an activated carbon layer for odours and some gases.
Budget for filters. Replacement filters are an ongoing cost; buy spares before winter, when everyone else does.
Seal the gaps. Older Shanghai apartments and lane houses can be draughty. A purifier can't keep up with a window that doesn't close.
Use a cheap monitor. An indoor PM2.5 monitor tells you whether the purifier is actually working.

Many newer serviced apartments and international schools have central filtration. Ask the landlord or agent what's fitted and when filters were last changed. See our guide to renting in Shanghai for what else to check before signing.

Masks

On bad days, a well-fitted KN95 or FFP2 mask is the practical choice for adults outside [3]. Fit matters more than brand: if your glasses fog, air is leaking around the edges. Masks are widely sold in Shanghai pharmacies and convenience stores. Small children are hard to fit, so for them indoor time and a purifier matter more.

Kids, asthmatics and outdoor sport

If you have asthma, or your kids do, do the prep in Australia before you leave.

See your GP for an up-to-date asthma action plan and enough preventer and reliever medication for the first few months. Our healthcare in Shanghai guide covers bringing medicine into China.
Ask your school what AQI level stops outdoor play and sport. Many international schools have a set policy, indoor sports halls and filtered classrooms. Our guide to international schools in Shanghai has more on choosing one.
Plan outdoor sport around the air. If you play footy, cricket or run with a club, check the AQI before training. Winter mornings can be worse than afternoons in smog season; in summer, early starts dodge the ozone.
Watch for patterns. A cough that clears every time you go home to Australia is worth mentioning to a doctor.

For many families, the routine becomes automatic within a month: check the app at breakfast, purifiers on, mask in the bag from November.

Want to know which purifier other Aussies swear by, or which school runs indoor PE when the AQI spikes? Ask in Cooee China, our Facebook group for Australians in China (join here).

Air quality in Shanghai: how to read the AQI and protect your lungs