The first time I opened an AQI app in China and saw a number over 200, I stared at it like it was a weather forecast written by a threat.

The sky did look wrong that day. Not dramatic movie-smog wrong, just dull and heavy, like someone had lowered the contrast on the city. My throat felt dry after a short walk. By lunch, I had changed my plans from outdoor wandering to museums and noodles.

That became the pattern. I did not panic about air quality, but I checked it.

What AQI actually means

AQI stands for Air Quality Index. It takes pollution measurements, especially fine particles like PM2.5, and turns them into a number.

Roughly:

AQI	How I think about it
0 to 50	Great. Go outside.
51 to 100	Fine for most travelers.
101 to 150	Noticeable haze, sensitive people should pay attention.
151 to 200	Unhealthy. I reduce long outdoor time.
201 to 300	Bad day. Mask outside, indoor plans preferred.
300+	Very bad. I would avoid unnecessary outdoor activity.

Under 100, I usually did not think much about it. Over 200, I could feel it. Not always immediately, but after walking for a while.

Cities are not all the same

Before the trip, I had a lazy mental image of “China pollution” as if the whole country had one sky.

It doesn’t.

Beijing can still have rough winter days, though it is much better than it used to be. Chengdu sits in a basin, so air can feel trapped. Xi’an and inland industrial cities can also get bad stretches.

Shanghai, Guangzhou, Shenzhen, and southern coastal cities often feel better because air moves more. Kunming has a reputation for cleaner air and, from what I saw, deserves some of it.

Season matters too. Northern winter is the one I would plan around most carefully. Summer rain can clear the air. Autumn is often beautiful. Spring can bring dust and sand in the north.

The mask question

For pollution, you want an N95 or KN95 mask. Surgical masks and cloth masks are not the same thing for PM2.5.

The nice thing is that masks are easy to buy in China, and wearing one is normal. Nobody cares. I kept one in my bag on days when the number looked iffy.

My own rule was:

• Above 150: consider a mask if I would be outside for a while
• Above 200: wear one outside
• Above 300: change the plan if possible

This is not medical advice. If you have asthma, heart issues, or serious respiratory problems, talk to a doctor before planning a winter trip to northern China.

How it changed my days

Bad air did not ruin the trip. It changed the rhythm.

On clearer days, I did the outdoor things: city walls, long walks, parks, riverfronts, temple complexes. On hazier days, I moved toward museums, markets, tea houses, restaurants, malls, and shorter walks.

China has enough indoor life that this did not feel like a disaster. Some of my better food days happened because I gave up on being heroic outside and let the day become about noodles, dumplings, and hiding from the air like a sensible person.

I added AQI and weather to China Ready Travel because of this exact behavior. I did not need a complex meteorology dashboard. I needed one glance in the morning that helped me decide whether today was a Great Wall day or a museum day.

What app should you check?

IQAir and AirVisual-style apps are useful because they show US AQI standards, which many travelers understand. China also has official readings, and sometimes the numbers differ because the standards differ.

The exact number matters less than the category and trend. Is it getting worse? Is tomorrow better? Is one neighborhood much cleaner than another? That is the practical part.

A few small things helped

Drinking more water helped with the dry throat feeling. Hotels with air purifiers were nicer on bad days. I avoided long walks beside heavy traffic when AQI was already poor.

I also stopped treating haze as a personal failure of planning. Sometimes the sky is just not cooperating. A good China itinerary needs some flexibility built in.

The situation has improved a lot over the last decade. That is true and visible. The bad days still exist. That is also true.

So my advice is boring but honest: check the AQI, bring or buy a proper mask, and do not schedule every outdoor highlight back to back with no room to swap days.

I am still figuring out how much air-quality guidance belongs inside a travel app without making it feel alarmist. The goal is not to scare people away. It is to help them make one good decision in the morning and then get on with the trip.