The U.S. Environmental Protection Agency (EPA) has developed a formula to convert PM 2.5 readings into an AQI value that can help guide health-related decisions.

FORBES: Air Quality In China

For example, an AQI value of 50 represents good air quality with little potential to affect public health, while an AQI value over 300 represents hazardous air quality.

FORBES: Air Quality In China

The U.S. Embassy in Beijing publishes AQI values for Beijing and other cities in China, and the Chinese Ministry of Environmental Protection provides its own air quality data for cities throughout the country.

FORBES: Air Quality In China

Increasingly, that vacuum is being filled by Iran and its proxies on the one hand and, on the other, insurgent Sunni forces, both those aligned with al Qaeda and those that have, at least until recently, been suppressing the AQI.

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