Poor air quality can affect your health quickly, especially during outdoor events.
Know the risks, check conditions before you go, and take the right precautions.
Source: https://www.nj.gov/health/world-cup/resources/air-quality/
Check current air quality conditions at AirNow.gov
Understanding the Air Quality Index.
The Air Quality Index (AQI) is a daily measure of how clean or polluted air is. The higher the number, the greater the health risk. During summer events, ozone and particle pollution are the most common concerns.