​​​Air Pollution 
Monitoring & Management
in China
Data on this page reflect joint effort of EPA, National Oceanic and Atmospheric Administration (NOAA), National Park Service ( NPS), tribal, state, and local agencies in establishing and developing the website of AIRNow, providing daily forecast on both AQI nationwide as well as real-time monitoring on five major air pollutants including particulate materials for ove 300 cities across the U.S..See more information on the AIRNow website (http://www.airnow.gov/). ​
Real-time Monitoring in U.S.
The widely applied AQI standard is also known as the AIRNow standard, which originates exactly from the source of these two up-to-date monitoring results. The coding criteria at the left bottom derive from the NAAQS and are referred to as the most recognized international regulations in air quality monitoring. Seen from the hourly updated graphs as "good" green dominates in both pictures with few "moderate" yellow spot and merely "sensitive-unhealthy" orange, the air quality in the U.S. is generally healthy and much better than that in China.
Take Philadelphia for example, there were 8 out 28 days in the passing February when the AQI shown in yellow rather healthy green. March performed better with only 5 days exceeded 0-50 range.