As we gear up to the New Year, I want us all to remember January 1, 2025. After a night of celebration, our region awoke to a grey, smoky haze over the Valley. It wasn’t fog, it wasn’t a cloudy day, it was a thick concentration of fine particulates known as PM-2.5. And it was caused by consumer fireworks. Environmental, News December 17, 2025 Fireworks are Breathtaking As we gear up to the New Year, I want us all to remember January 1, 2025. After a night of celebration, our region awoke to a grey, smoky haze over the Valley. It wasn’t fog, it wasn’t a cloudy day, it was a thick concentration of fine particulates known as PM-2.5. And it was caused by consumer fireworks. On January 1, 2025, the Maricopa region had the worst air quality in the nation. Based on the PM-2.5 data collected from global monitoring stations managed by the EPA, one of the region’s monitors reported the third-worst air quality in the world! What is PM 2.5? PM stands for particulate matter: a mixture of solid particles and liquid droplets found in the air. PM-2.5 is fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller – a fraction of the size of a human hair. If the air is visibly cloudy from 2.5, that indicates an extremely high level of PM-2.5, which is harmful when inhaled. Size comparisons for PM particles. Source: EPA The Effects of Fireworks There is a difference between the effects of commercial and consumer fireworks. Commercial fireworks, like those used at a professional sports event or a city-sponsored 4th of July show, explode higher in the atmosphere, where pollutants are dispersed. Consumer fireworks, like the type used in home celebrations on New Year’s Eve, explode much closer to the ground into the air we breathe. All fireworks contain toxic chemicals that are used to produce the colors and flashes that make fireworks beautiful. Winter Inversion The Maricopa region experiences a wintertime phenomenon called inversion. Inversion occurs when cooler air near the ground is pushed down by warmer air higher in the atmosphere. The mountains surrounding the region keep this “trapped” air from mixing with cleaner air, causing the high levels of pollution in the air we breathe. The combination of the wintertime inversion and the number of fireworks ignited on New Year’s Eve creates a harmful, even toxic, plume of smoke that lingers across the region. Everyone, not just those with underlying health conditions, is impacted by this pollution. This year, I encourage you to rethink how you celebrate New Year’s Eve. Consider your neighbors, the people you care about, and your own health. Yes, fireworks are stunning, but here in the Maricopa region during the winter, they are literally taking our breath away. Learn more at azmag.gov/fireworks Sincerely, Mayor Alexis Hermosillo, Chair MAG Regional Council Published December 17, 2025