What is the normal PM value? Understanding air quality and health impacts
In recent years, air quality issues have attracted much attention, especially the concentration of PM2.5 and PM10, which have become important indicators for measuring air pollution. So, what is the normal PM value? This article will analyze it for you from multiple perspectives such as definitions, standards, health impacts and recent hot topics.
1. What is PM value?
PM (Particulate Matter) refers to particulate matter in the atmosphere, which is divided into PM2.5 (≤2.5 microns) and PM10 (≤10 microns) according to diameter. PM2.5 can penetrate deep into the lungs and even the blood, causing greater harm to human health.
2. International and domestic standards for PM value
Countries have different limits for PM values. The following is a comparison of air quality standards from major agencies and countries:
| Institution/Country | PM2.5 daily average limit (μg/m³) | PM10 daily average limit (μg/m³) |
|---|---|---|
| World Health Organization (WHO) | 15 | 45 |
| Chinese National Standard (Level 1) | 35 | 50 |
| U.S. EPA | 35 | 150 |
| European Union | 25 | 50 |
Note: China’s first-level standard applies to special areas such as nature reserves, while the second-level standard (PM2.5 daily average of 75 μg/m³) applies to general residential areas.
3. Impact of PM value on health
Health risks under different PM concentrations:
| PM2.5 concentration (μg/m³) | health effects |
|---|---|
| 0-35 | Good, no obvious risks |
| 35-75 | Sensitive people may develop symptoms |
| 75-150 | Healthy people become unwell and the risk of cardiopulmonary disease increases |
| >150 | In case of emergency, everyone needs to reduce outdoor activities |
4. Recent hot topics: Global PM pollution and response
1.New Delhi smog crisis in India: In early October, the peak PM2.5 level in New Delhi exceeded 500 μg/m³, schools were closed, and the government initiated emergency measures.
2.Warning for heating season in northern China: Many places have released pollution prevention and control plans for autumn and winter, and it is expected that PM values may increase in stages starting in November.
3.WHO updated guidelines spark controversy: Some developing countries believe that its standards are too strict and difficult to achieve.
5. How to protect against PM pollution?
1. Pay attention to the real-time Air Quality Index (AQI). 2. Reduce outdoor exercise when PM2.5>75. 3. Use N95 masks or air purifiers. 4. Eat more antioxidant-rich foods.
Summary
The ideal value of PM2.5 should be lower than 35μg/m³, but in practice it needs to be combined with regional standards. Recent pollution incidents in many places around the world remind us that air quality is closely related to health. It is recommended that the public obtain data through official channels (such as the Ministry of Ecology and Environment APP) and conduct scientific protection.
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