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.
The state departments of health and environmental quality have issued advisories about fireworks pollution in recent weeks. On Wednesday, Salt Lake City's sustainability office did too.
"The particulate matter in fireworks smoke is of concern, in addition to the chemicals used to color the fireworks," the office advised residents.
The office urged the very young, the very old and people with heart and lung issues to take precautions such as avoiding large shows and staying indoors, if necessary.
"Skip the personal fireworks you'll save money and breathe a little easier," the sustainability office said in its advisory.