Short answer
China's air is far cleaner than its reputation suggests. Beijing's annual average PM2.5 has fallen by roughly 70% since 2013, to around 27 micrograms per cubic metre in 2025, and most tourist cities are acceptable for most of the year. What remains is a seasonal problem, not a year-round one.
Two windows matter. The northern heating season from mid-November to mid-March, when weather inversions trap pollution over Beijing, Hebei and the northeast, and the spring dust season from March to May, when Gobi sand blows across the north. Outside those windows, a visitor's exposure is close to what you would get in a large European or North American city.
Practical response: check the index each morning, keep one flexible day in each city so a clear day can be spent outdoors, and carry a KN95 or N95 mask for days above AQI 150. A loose surgical mask will not do much. Indoor sights, food streets and shopping malls make good fallbacks when the sky turns grey.
How to read the AQI in China
China runs its own index from 0 to 500, published with a band name, a number and a colour. The colours are the fastest way to read a city at a glance — green is fine, anything red or purple is a day to change plans.
| AQI | Chinese band | Colour | What it means for a visitor |
|---|---|---|---|
| 0-50 | 优 (excellent) | Green | No adjustment needed. Long walks, hikes, viewpoints. |
| 51-100 | 良 (good) | Yellow | Still a normal day for a healthy adult. Sensitive groups may notice it on hard exercise. |
| 101-150 | 轻度污染 (lightly polluted) | Orange | Visible haze in the distance. Fine for a normal day out; sensitive groups take it easier. |
| 151-200 | 中度污染 (moderately polluted) | Red | Wear a mask outdoors, shorten strenuous activity, prefer indoor sights. |
| 201-300 | 重度污染 (heavily polluted) | Purple | Move the outdoor day. Museums, malls, long meals. |
| 301-500 | 严重污染 (severely polluted) | Maroon | Rare, and mostly a northern winter event. Stay indoors where you can. |
The main pollutant on bad days is PM2.5, the fine particulate fraction that reaches deep into the lungs. PM2.5 is where the health effect is, and it is the number worth looking at if the app offers it. A useful shorthand: a daily PM2.5 above about 75 µg/m³ is a hazy day, and above 150 µg/m³ is one to plan around.
Why two apps give you two different numbers
Most visitors notice this on the first morning. Your phone's weather app might say 100 while IQAir says 155 for the same city, at the same hour.
Nothing is broken. The index converts a pollutant concentration into a number using breakpoints, and China and the US EPA use different ones. The US scale is stricter. The practical result is that a PM2.5 level of roughly 35 µg/m³ reads near 50 — "excellent" — on a Chinese scale and about 100, "moderate", on a US-based one.
| PM2.5 (µg/m³, 24-hour) | China AQI band | US EPA AQI band |
|---|---|---|
| Around 20 | 优 / excellent | Moderate |
| Around 35 | 优 / excellent (about AQI 50) | Moderate (about AQI 100) |
| Around 75 | 良 / good (about AQI 100) | Unhealthy for sensitive groups (about AQI 160) |
| Around 150 | 中度污染 / moderate (about AQI 200) | Unhealthy (about AQI 235) |
Use one app consistently and read the band, not the number. If you are deciding whether to climb a mountain, the US-based app is the more cautious of the two.
Where and when the air gets bad
Chinese air quality is regional and seasonal. The pattern below is the usual one, though individual years diverge — a wet winter or a strong spring wind field can change everything, so check the forecast for your own dates.
| Region | Worst months | Usual pattern |
|---|---|---|
| Beijing, Tianjin, Hebei | Nov-Mar, plus March-May for dust | Heating season plus winter inversions; autumn (September-October) is often the clearest stretch of the year |
| Northeast: Harbin, Changchun, Shenyang | Nov-Mar | Long heating season and very cold, still air. Harbin's Ice Festival falls inside it |
| Shanghai, Hangzhou, Suzhou, Nanjing | December-February | Winter peaks are milder than the north; summer is humid and usually cleaner |
| Chengdu, Chongqing, Xi'an | November-February | Basin and valley geography holds pollution in place for days at a time |
| Guangzhou, Shenzhen, Xiamen, Hong Kong | Year round but mild | Among the cleanest large-city air in the country; summer rain washes it further |
| Urumqi, Dunhuang, Xinjiang and Gansu | March-May | Dust is the main event and it is coarse, visible and short-lived |
| Lhasa, Kunming, the southwest plateau | Rarely | High, windy and thinly populated; consistently the cleanest air in China |
When a mask actually helps
A mask is a tool for a specific situation: outdoors, on a day the air is bad, for a period of a few hours. Outside that, it is wasted.
- KN95 or N95, not the flat blue ones. The fitted, cup-shaped masks filter the fine particles that matter. A loose surgical mask leaks around the edges and does little for PM2.5.
- Fit beats the label. A mask that gaps at the nose bridge is doing a fraction of its rated work. Press the metal strip down over the bridge.
- Thresholds. Above AQI 150 the masks start to make an obvious difference on a long walk; above 200 they are the difference between a short outing and a comfortable one. Below 100, take it off.
- Where to buy. Any pharmacy or convenience store in a Chinese city sells packs of KN95 masks; hotels often keep a few at the front desk. Stock up in a supermarket rather than from a station kiosk and check the shelf price.
- When not to bother. Indoors in a filtered building, on the metro, and in a hotel room. If your room has a purifier, use it and skip the mask.
Planning an itinerary around the air
Air quality is a forecast, not a fixture. Treat it like rain: check it, plan a fallback, and do not cancel a trip over it.
- Check the index each morning, onceAny weather app will do, and Chinese cities also publish through official channels. Read the band and the colour rather than comparing numbers between apps.
- Put the outdoor day where the clear day isIf your Beijing window includes one green day, spend it on the Great Wall or a park. Save the indoor halls for the grey one. If you are flexible, this single rule is worth more than any mask.
- Rank your sights by exposureMountain ridges, city walls, boat trips and long walks are the exposure-heavy ones. Museums, temples with covered halls, malls, teahouses and food streets are the light ones. The Forbidden City works on either kind of day.
- Adjust the intensity, not just the locationOn a bad day, walk instead of cycling, take the metro instead of jogging along the river, and break a long walk into two shorter ones with indoor stops.
- Ask the hotel about the roomA room with a purifier, or one on a higher floor away from a main road, makes a real difference on a heavy day. Most mid-range and upscale Chinese hotels have purifiers available on request.
- Use the metro as an air corridorChina's metro systems, malls and big museums are large, filtered spaces. A polluted day is a good day to move between them underground.
If you have a lung or heart condition
Short-term exposure on a two-week trip is a low risk for a healthy adult. It is a different calculation if you have asthma, COPD, heart disease, are pregnant, or are travelling with young children or an older relative.
For those groups: bring your regular medication and a spare prescription, follow the official advice on the days the index is high, keep outdoor time short, and treat a red band day as an indoor day. Talk to your own doctor before you travel rather than after you arrive. If breathing becomes difficult or you cannot get your usual medication, hospitals in major cities have international clinics — see the healthcare guide — and pharmacies are covered in the pharmacy guide.
Frequently asked questions
Is air pollution in China still a problem for tourists?
Much less than it was. Beijing's annual average PM2.5 concentration has fallen about 70 percent since 2013, to roughly 27 micrograms per cubic metre in 2025, and most tourist cities are acceptable for most of the year. Bad days still happen, mostly in the northern winter and during spring dust storms, and they are worth planning around rather than ignoring.
How do I read the AQI in China?
China uses a 0 to 500 index with six bands: 0-50 excellent, 51-100 good, 101-150 lightly polluted, 151-200 moderately polluted, 201-300 heavily polluted, and above 300 severely polluted. Chinese apps show the band name and a colour, so you can read the situation without knowing the number's meaning.
Why do two air quality apps show different numbers for the same city?
Because the index is calculated against different breakpoints. The US EPA scale is stricter, so a PM2.5 reading of about 35 micrograms per cubic metre comes out near 50 excellent on a Chinese scale and about 100 moderate on a US-based app. The underlying air is the same, and the numbers are not contradictory.
When is air quality worst in China?
Two periods dominate. The northern heating season, roughly mid-November to mid-March, when coal and gas heating plus winter inversions trap pollution over Beijing, Tianjin, Hebei and the northeast. And spring, roughly March to May, when Gobi dust storms push coarse particles across the north and northwest.
Do I need to wear a mask in China?
Only on the bad days, and only outdoors. A well-fitted KN95 or N95 filters most fine particles, while a loose surgical mask does very little. On days when the AQI is above 150 or the air looks hazy, a mask makes a long walk or a temple visit far more comfortable. It does nothing useful indoors.
Which Chinese cities have the best and worst air?
Coastal and southern cities such as Xiamen, Shenzhen, Guangzhou, Kunming and Lhasa generally record the lowest yearly PM2.5, and Lhasa in particular is clean year round. The northern industrial belt, including parts of Hebei and the northeast, and basin cities such as Xi'an and Chengdu in winter, record the highest. Seasonal patterns shift year to year.
Should air quality change my itinerary?
Build in flexibility rather than cancelling anything. Save the Great Wall, the hikes and the long walking days for the clearest days in your window, and keep museums, temples, malls and food streets as the fallback. A day of AQI 200 is a good day for the Forbidden City's indoor halls and a poor day for a mountain ridge.
Does air pollution affect hotels and indoor spaces?
Indoor air tracks outdoor air, but filtered rooms are much better. Many mid-range and upscale Chinese hotels put a purifier in the room, and shopping malls, museums and metro systems are large and filtered. Ask for a room with a purifier, or for a higher floor, if the forecast for your stay looks poor.
Is a bad air day harmful for a short trip?
For a healthy adult on a two-week trip, the exposure is short term and the risk is low. It matters more if you have asthma, a heart or lung condition, are pregnant, or are travelling with young children or an older relative, who should follow a lower threshold and stay indoors on the worst days. Speak to your own doctor before travelling if this applies to you.
Related reading
Air quality sits alongside the other practical health questions on a first trip. The safety guide covers the scams and everyday risks that are more likely to affect your trip than the index, and the healthcare guide explains where to go if something on this page does become a problem.
Compiled from published PM2.5 trend data for Beijing and national averages, Chinese air quality index band definitions, US EPA breakpoint comparisons, and seasonal dust and heating-season reporting, cross-checked against two independent sources on 30 September 2026. Air quality varies by day, by district and by year, and the two index scales are not interchangeable — the reading in front of you on the day is what matters. Nothing on this page is medical advice.