Traditional Culture Encyclopedia - Weather forecast - What are the three standard indexes of smog yellow, orange and red?

What are the three standard indexes of smog yellow, orange and red?

Level 1 (extremely heavy pollution), that is, the air quality index in this area has been above 500 for 24 consecutive hours.

Grade II (serious pollution), that is, the air quality index in this area for 48 hours is within the range of 30 1 to 500 (inclusive).

Grade III (heavy pollution), that is, the air quality index in this area for 72 hours is within the range of 20 1 to 300 (inclusive).

Haze weather is serious, so you need to take your own precautions. We can install a fresh air system at home. My home decoration is a five-degree and five-constant fresh air system, and it is also very comfortable in foggy days.