Air quality in Shanghai: AQI, purifiers and masks

Most days in Shanghai are fine to be outside. The problem days cluster in winter, and the families who handle them best check an app every morning and run a purifier at home.

The short version

Shanghai's official figures show a 2025 average PM2.5 of 26.3 µg/m³, down 7.4% from 2024, and 88.5% of days rated good or better on China's scale [1].
Winter is the bad season. PM2.5 averaged 42.5 µg/m³ in January 2026, against 14.7 µg/m³ in September 2026 [2][3].
China's AQI and the US AQI use different scales, so the same air can get a different number and label depending on which app you use.
Shanghai switched to a new national air quality standard (GB 3095-2026) on March 1, 2026, so recent figures aren't directly comparable with older ones [5].
A good HEPA purifier at home and a well-fitting N95 or KN95 mask for bad days are the standard toolkit.

How to read the AQI

The Air Quality Index turns pollutant readings into one number. Back in the States you've probably seen it on a weather app during wildfire season. The US version, which the EPA runs through AirNow, goes from 0 to 500 [6]:

US AQI	Category	What it means
0–50	Good (green)	Little or no risk [6]
51–100	Moderate (yellow)	Acceptable; unusually sensitive people may be affected [6]
101–150	Unhealthy for Sensitive Groups (orange)	Kids, older adults and people with heart or lung conditions may be affected [6]
151–200	Unhealthy (red)	Some of the general public may be affected [6]
201–300	Very Unhealthy (purple)	Health alert: everyone's risk increases [6]
301+	Hazardous (maroon)	Emergency conditions [6]

China's official AQI also runs from 0 to 500 and also has six levels, but its breakpoints are based on Chinese air quality standards, not the EPA's. When the Shanghai government says a day was "good or better," it means good under the Chinese scale. Pick one scale and stick with it so you're comparing apples to apples. Many American families use the US scale because it's what their pediatrician back home will recognize.

The pollutant most people watch is PM2.5, fine particles small enough to get deep into the lungs. In summer, ozone matters too. Shanghai's monthly reports track both, along with PM10, nitrogen dioxide, sulfur dioxide and carbon monoxide [3].

Where the data comes from

You don't need to guess. Shanghai publishes a lot of data:

The Shanghai Municipal Bureau of Ecology and Environment publishes monthly and year-to-date air quality reports, in Chinese, with citywide and district figures [1][2][3]. Its PM2.5 and AQI numbers come from 19 national monitoring stations, four in Pudong and one in each other district [2]. It also runs mobile monitoring of road dust on thousands of streets [2].
China's national monitoring network. China's national environmental monitoring center publishes station data nationwide.
The US government. The State Department points Americans to AirNow for data from US embassy and consulate monitors in China, and to China's Ministry of Ecology and Environment for city data [8].
Aggregator apps. IQAir's Shanghai page, for example, pulls from 54 stations using data from the Shanghai bureau and the national monitoring center, and shows readings on the US AQI scale [7].

A tip: set your app to the station nearest your home and your kid's school, not just the citywide average. District numbers can differ noticeably on the same day [2].

What changed in 2026

On March 1, 2026, Shanghai began monitoring, forecasting and publishing air quality under the new national standard GB 3095-2026, and said AQI calculations would change accordingly [5]. The city recalculated its 2026 and comparison 2025 figures under the new standard in its later reports [4]. Bottom line: be careful comparing a 2026 "good day" percentage with one from 2024.

Seasonal patterns: winter is the tough stretch

Shanghai's own monthly data shows the pattern clearly [1][2][3][4]:

Period	Citywide PM2.5	Share of days good or better (China scale)
December 2025	36.2 µg/m³	93.5%
January 2026	42.5 µg/m³	90.3%
September 2026	14.7 µg/m³	100%
Full year 2025	26.3 µg/m³	88.5%
January–September 2026	23.6 µg/m³	87.9%

A few things stand out:

January's average was nearly three times September's. Winter weather traps pollution and brings in pollution from upwind regions, so cold, still days are the ones to watch.
The long-term trend is improving. PM2.5 for the first nine months of 2026 was down 6.7% on the same period in 2025 [4], and December 2025 was down 17.5% year over year [1].
District differences matter. In January 2026, district averages ranged from 35.2 µg/m³ in Chongming, the island district, to 49.2 µg/m³ in Jinshan [2]. Central districts like Huangpu, Jing'an and Xuhui sat in the low 40s [2].
Roads are dustier than the averages suggest. The city's mobile monitoring of road PM10 averaged more than 100 µg/m³ in December and January [1][2]. If you're choosing between apartments, one on a quiet lane may beat one over a busy arterial road.

Summer brings a different issue. Warm, sunny days raise ozone, which can push the index up even when PM2.5 is low.

Purifiers and masks

Air purifiers at home

Most American families in Shanghai run purifiers, especially in bedrooms. What to look for:

A true HEPA filter, sized for the room. Check the clean air delivery rate (CADR) against your room's square footage.
Replacement filters you can actually buy locally. Chinese e-commerce apps stock filters for the major brands.
A cheap indoor monitor, so you can see whether the purifier is keeping up.
Sealing. Older Shanghai apartments often have drafty windows. Weather stripping makes a bigger difference than a second purifier.

Many international schools, offices and newer residential buildings in Shanghai have central air filtration. Ask before you sign a lease or a school contract.

Masks for bad days

On high-AQI days, a cloth or surgical mask won't do much against fine particles. Use a well-fitting N95 (the US standard) or KN95 (the Chinese standard equivalent). Fit is everything: a beard or a loose seal around the nose lets air in around the edges. Masks are sold in pharmacies and convenience stores all over the city.

Protecting kids and sensitive family members

Kids breathe faster and spend more time running around outside, so they're the ones families plan around. Here's what Americans in Shanghai commonly do:

Check the AQI before school and before weekend plans. Use the station nearest to you.
Know your school's policy. Many international schools move recess and sports indoors above a set AQI. Ask what scale and threshold yours uses.
Move exercise indoors on bad days. Long runs and soccer practice can wait.
Run the purifier in the bedroom overnight, with the door closed.
Talk to a doctor if anyone has asthma or a heart or lung condition. Bring enough of your regular medications from home while you find a local doctor; our guide to healthcare in Shanghai covers English-speaking options.

New arrivals often find the first winter the hardest. Parents in our community group for Americans in China trade notes on purifier brands, filter suppliers and which schools handle bad-air days well.

Air quality in Shanghai: reading the AQI and protecting your family