What is the Difference Between China’s AQI and the U.S. AQI?
Air Quality Indexes (AQIs) present air quality information in a simple, understandable way for the public. Both China and the United States use AQI systems to convert concentrations of various pollutants into a single value, from 0 (clean air) to 500+ (heavily polluted). However, the two systems differ in the pollutants they prioritize, the standards they follow, and how they calculate air quality over time.
The U.S. AQI is based on guidelines set by the U.S. Environmental Protection Agency (EPA). It includes pollutants like particulate matter (PM2.5, PM10), ozone (O₃), carbon monoxide (CO), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂). China’s AQI covers similar pollutants but follows national standards, leading to some differences in reported values.
IQAir displays both the U.S. AQI⁺ and the CN AQI⁺ on its platform. U.S. AQI⁺ aligns with the EPA’s AQI definitions but provides more real-time data by calculating based on hourly concentration averages, offering a timely perspective on air quality conditions. Similarly, CN AQI⁺ is based on China's official reporting protocols but uses hourly averages for a more immediate reflection of air pollution levels.
Both AQIs classify air quality into six color-coded categories, each associated with specific health recommendations. This system ensures the public receives clear and actionable information, regardless of whether they are viewing U.S. AQI⁺ or CN AQI⁺ data.
