Pioneer Day festivities boosted pollution in northern Utah communities Tuesday and Wednesday.
In Ogden, microscopic smoke from fireworks pushed PM 2.5 pollution to 164.8 micrograms of pollution per cubic meter of air, a level nearly five times what is considered healthy under federal regulations. But the midnight pollution spike was short-lived, and air quality returned to its normal, acceptable levels before morning.
Meanwhile, particulate pollution levels jumped in Salt Lake, Box Elder, Cache and Utah counties overnight Wednesday. And, on Tuesday, PM 2.5 briefly reached "unhealthy" levels in Box Elder, Cache and Duchesne counties.