Traditional Culture Encyclopedia - Weather inquiry - Why is the weather inside nails always seriously polluted?

Why is the weather inside nails always seriously polluted?

It's really serious. There are many aspects to judge the air pollution index, such as dust and carbon dioxide. I don't know if your pollution is so serious because of the high dust concentration, or it may be caused by pollutants contained in automobile exhaust or industrial exhaust. Whatever the reason, it is definitely harmful to human body.