This website provide daily the Air Quality values for different cities all over China.
Even though the values are provided by the Chinese government and are much lower than the actual values (you should add something like 30-50 to reach the real international standards).
In fact in Beijing the US embassy started to disclose its own Air Quality values: much higher than the the Chinese authorities values. The authorities recognized that they calculate differently therefore lowest value.
Small particles pollution: What does PM2.5 and PM10 mean?
Now you should understand what Air Quality Index values PM2.5 and PM10 mean.
I checked on wikipedia.
The index calculates the number of particles in the air.
- The particles are of different origins: coals burning, wood burning, volcano, dust, power plant, diesel, construction...
- The particles have different sizes: the smallest size being the most dangerous! They can enter your lungs and then your blood. They will then travel to your organs: heart, brain... Some particles have a chemical toxicity. They can lead to cancer or heart attack.
PM10 provides a number of particle smaller than 10 micron
PM2.5 provides a number of particle smaller than 2.5 micron
How about gazes and fumes?
Gazes and fumes are another type of pollution.
It includes Nitrogen oxides, Sulphur dioxide, Carbon monoxide, hydrocarbon chemicals, low level ozone. However this kind of pollution is not a main concern in China nowadays. As you can see from the AQI website, the value for SO2, NO2, CO are in the norms.
Changsha Air Quality
In Changsha the Air Quality Index values are very bad, almost as bad and sometimes worst than in Beijing!
This is probably due to heavy intensive non-stop construction.
Wear a mask!
We should all wear masks. But no one is wearing any... People don't realize the danger. They don't know they should wear a mask while outside or while doing sport.
When living in a provincial city like Changsha you seldom think that pollution can be lethal. And very few talk about it. I even didn't know that you could buy efficient mask.
In fact a mask can protect you from inhaling too many particles. Most mask can filter particles as small as 0,3 micron and as much as 99% of these particles can be filtered.
Also some masks like Respro provide another protection against gazes and fumes. It is always nice not to smell any car gazes. Respro is the only mask (maybe with 3M) that has a Dynamically Activated Charcoal filter. But this comes with a price.
Overall, I recommand Totobobo mask for China in term of quality and price.
While using a mask, you should change the filter quite often and this has a cost.
To go further, you can have a look at this great website.