The poor air quality level in Phoenix on Friday hit the highest value recorded since reliable recording began in 2011, according to the Arizona Department of Environmental Quality.
The smoke air quality index, which came in at 272 on Friday, is considered very unhealthy and comes close to reaching hazardous levels.
Symptoms can include itchy eyes, nose and throat, wheezing, coughing, shortness of breath, chest pain and upper respiratory issues.
Exposure can increase the number and severity of asthma attacks, aggravate bronchitis or other lung disease and reduce the body's immune system.
To help, The Maricopa County Air Quality Department declares a "No Burn Day" often, which prohibits wood burning in residential fireplaces, fire pits and other outdoor fires.
TIP: Download the Air Arizona mobile app and check it before you burn.