The Las Vegas area could be particularly smoky on New Year's Day after kicking off 2016 with fireworks.
The Clark County Department of Air Quality issued an air quality advisory in effect tonight, New Year's Eve, through tomorrow.
There isn't an unhealthy level of air pollution currently.
The warning is precautionary, particularly for those with respiratory and other health concerns who may have their conditions aggravated by the smoke and small dust particles that come from firework displays.
Officials expect 332,000 people to watch fireworks shoot from seven rooftops on the Las Vegas Strip and crowd Fremont Street in downtown.
The county said children and the elderly should also consider staying indoors to avoid smoke exposure.
Limiting outdoor exercise, keeping windows closed and changing dirty air filters are also suggested.