Scientific meanings behind the numbers: the truth of health impact of smog


April 23, Beijing

You may have seen news claiming that “Smog has caused X millions of deaths, and economic losses of X RMB”. How are these numbers calculated and interpreted? Doctor Wei Wan, Air quality specialist of Clean Air Asia introduced health impact assessment methodology of outdoor air pollution and important scientific issues on air pollution which attracts around 50 participants from environmental industry, finance, media, and academy.

Human deaths and economic losses caused by air pollution have been studied and discusses more extensively recently. Invited by Beijing Energy Network, Dr. Wan Wei gave a speech on how to interpret the scientific numbers by answering 8 questions: 1) How to understand the health risks of air pollution? 2) Why is PM2.5 critical? 3) How to establish relationship between pollution concentration and the risk of health effects? 4) What is the baseline or threshold for damage? 5) How to choose reliable methods and parameters? 6) Is good air quality index equal to clean air? 7) Can we monetize life and health? 8) Why monetization is necessary?

One of the highest concern questions is how to establish relationship between pollution concentration and the risk of health effects. Dr. Wan Wei said that when the Air Quality Index (AQI) indicates that air is clean, it does not mean the air is without any health risk. Air pollution does not have safe “threshold value”, and the definition of AQI varies among different countries. Dr. Wan Wei also shared a picture comparing AQI for PM10 in different countries all around the world.

In the discussion session, the audience asked questions on specific methodology of environmental and health impact, people’s daily life and exercise activities, as well as Clean Air Asia’s programs. Clean Air Asia aims to establish more platforms to help the general public know more knowledge on air pollution and its protection measures.


Clean Air Asia was established in 2001 as the premier air quality network for Asia by the Asian Development Bank, World Bank, and USAID. Its mission is to promote better air quality and livable cities by translating knowledge to policies and actions that reduce air pollution and greenhouse gas emissions from transport, energy and other sectors. Clean Air Asia has 8 country networks and has offices in Manila, Beijing and Delhi.

Clean Air Asia China Office