Arizona Air Quality Information

Phoenix: July 4th Impacts on Air Quality


The big question we hear around July 4th: do fireworks impact air quality?

The short answer, yes. We do typically see a rise in smoke levels (PM2.5) in the Valley during the evening of July 4th; however, it rarely results in an exceedance of the federal health standard. Using air quality data from 2010-2018, the Valley has exceeded the federal health standard for PM2.5 only once on July 4th, which occurred in 2014.

This year, our hourly PM2.5 forecast for Phoenix is showing the peak time period for elevated smoke from fireworks being between 8 and 11 pm.

[View Phoenix 5-Day Hourly Air Quality Forecast]

There are some differences when looking at the impact of fireworks on July 4th versus New Year's. First, on New Year's they are typically being launched around the same time of night (just before or after midnight) as compared to throughout the entire evening on July 4th. The weather is also much different. Strong inversions develop during the winter months trapping smoke from fireworks right near the surface. In the summer, the inversions are often weaker, allowing smoke to disperse higher into the atmosphere during the overnight hours.

Perhaps the largest way fireworks could have an impact on air quality is if they start wildfires. Be sure to use extreme caution and follow all laws when using fireworks across the state. A wetter winter allowed grass to grow in large quantities. This grass has now dried out, which has increased the fire danger. It only takes one spark to ignite a wildfire, and with plentiful fine fuels (grass) these fires can quickly spread.

To view City of Phoenix firework safety information click HERE.