Open the Channel of Old and New Knowledge —— Talking about Air Quality Index

Recently, I moved from the suburbs of Pudong, Shanghai to the urban area, and began to pay attention to what range of air quality can be used for outdoor sports. When I was in Zhihu this morning, I saw a foreigner named Thomas Talhelm answer: How much is the air index suitable for running?

The author demonstrates the conclusion that Beijing is not suitable for outdoor sports through data. From this, I learned about the standards of PM2.5 in the United States and the World Health Organization. I found that the American Embassy even tested the air quality index. When I opened the official website of the US Embassy in Shanghai, I really saw this option (slightly surprised), which made me no longer doubt the reliability of the data.

Knowing a little about PM2.5, I know that PM2.5 in Beijing is definitely not low, but I didn't expect it to be so much higher than the standards of the World Health Organization and the United States, so I checked the PM2.5 and air quality index standards of China and the United States online and found this table:

Thomas said that the standard of PM2.5 with good air quality in the United States is 12 micrograms, while that in China is 35 micrograms. For example, today (20 17/3/ 1 1), Shanghai's air quality index is 82, which is second-class in the country. Because there is a complex conversion relationship between air quality index and concentration value, I will not introduce it in detail. As can be seen from the table, the average daily concentration in Shanghai today should be 35~75 micrograms, but this concentration is at least the third-grade light pollution of American standards. The information tells me that China's PM2.5 standard is just on the road, which is the most relaxed transitional standard, but the United States has been included in the national standard since 1997. So if we want to do outdoor activities, we must find a way to convert them into American standards. Domestic air quality index is less than 50, and PM2.5 is less than 35 micrograms, which is suitable for outdoor sports. If it is higher than 50, it is at least slightly polluted according to American standards. Please try to minimize outdoor sports.

Looking through Thomas' other answers, I can see the PM2.5 data of five cities in China in the last five years, as shown below. Because I am in Shanghai, I will focus on the air quality in Shanghai. 20 1 1, the average value of PM2.5 in Shanghai is about 80 micrograms, and 20 16, the average value drops to about 50 micrograms. 50 micrograms is also light pollution in the United States, which is not suitable for outdoor sports.

Although through data argumentation, I have come to the conclusion that Shanghai is not suitable for outdoor sports, it is inevitable that Thomas will be somewhat imprecise considering the average annual value of PM2.5. Because we look at the daily air quality index to decide whether we can exercise outdoors. So I checked the air quality summary table of Shanghai on 20 16 online, as shown below. There are 109 days in a year (close to 1/3) when the air quality index is less than 50, that is, the PM2.5 is less than 35 micrograms, which is suitable for outdoor activities, and it is not suitable for outdoor activities at other times.

Conclusion: Because the domestic standard of PM2.5 is relatively loose, we should try our best to decide whether to participate in outdoor activities according to the air quality standard of the United States. The simplest way is that the air quality index is less than 50, and you can participate in outdoor activities. If it is higher than 50, please reduce outdoor activities;

Inquiry question: If the air quality index is higher than 50 (that is, PM2.5 is higher than 35 micrograms), can you filter particulate matter by wearing a mask and conduct outdoor activities normally? This problem will be studied later, which is a problem to be discussed later.

P.S. This article is written according to the teacher's "Four Questions on Communication Channels between Old and New Knowledge". According to this answer, I want to see what knowledge I have, what knowledge I have learned, what knowledge I can acquire through exploration, and what knowledge is suitable for long-term exploration. Problems that need to be explored for a long time can be followed up, and everyone can give their own views on my analysis. Thank you!