Millions of Americans have been urged to avoid driving amid concerns over high air pollution levels.
Air quality alerts were issued across parts of Illinois, Colorado, Wyoming, and Arizona on Thursday, according to the National Weather Service (NWS).
The warnings mean ground-level ozone and particulate concentrations are forecast to reach dangerous levels. In some areas, the pollution comes from drifting wildfire smoke.
Why It Matters
The NWS warned that both sensitive groups-such as children, seniors, and individuals with preexisting respiratory or heart conditions-and the general public might experience health effects linked to poor air quality in the affected regions…