The 12 Days of Christmas? How about the 10 Days of Inversion?

By DEQ Communications Office

Utah kicked off its winter inversion season in full force in early December with gunky air that persisted for 10 straight days.

2017 Salt Lake City inversion

 The Utah Department of Environmental Quality took to its Facebook page to provide residents with regular updates, tips for reducing emissions, and links to our air-quality monitoring data. We’ve put together a day-by-day compilation of our posts and pictures to show how an inversion begins, builds, and dissipates — in this case, over the course of 10 days.

Inversion alert!

“Utah is due for its first major inversion of the season this week, and the Utah Department of Environmental Quality‘s Division of Air Quality (DAQ) has issued a mandatory no-burn action that includes hefty fines for those violating the no-burn rules.

DAQ research suggests that the amount of wood smoke in the air on no-burn days is about the same as when the ban isn’t in effect That means some folks are still burning wood even on no-burn days! We hope residents will take the impacts of wood burning more seriously and pay attention to the burn conditions. That cozy, romantic fire in your fireplace is bad for our air and bad for your health.”

Inversion: Day 1

“It’s the first mandatory action day of the year. This means wood-burning restrictions are in place for Utah, Salt Lake, Davis, Weber, Box Elder, Cache, and Tooele counties. With a high pressure system sitting over Utah, northern Utah valleys will be under an inversion for the next week. As the pollution starts to build up, it increases the harm to the lungs and hearts of people with pulmonary and cardiac conditions. Act now to protect your and your neighbor’s health by reducing driving, taking Ride UTA and avoiding heavy outdoor activity. To learn more about ways you can help, check out these tips from our friends at Utah Clean Air Partnership (UCAIR).

Inversion: Day 2

2017 Salt Lake City inversion
Day 2

“Pictures from this morning show the PM2.5 pollution building up in the valley. The U.S. National Weather Service (NWS)‘s forecast has pegged this as a prolonged inversion episode. No significant changes are predicted over the next few weeks.

What can you do? A lot! Concentrations are not yet in the dreaded, unhealthy “red” range. Now is the time to take steps to help reduce the severity of this inversion before human-health risks rise.

  1. Consider taking Ride UTA. It’s a lot easier than most people think. Find the easiest way to get to work using the scheduling tool on the UTA website.
  2. Remember to trip chain by running all your errands at once. It will help cut personal emissions and save you a bunch of time this holiday season.
  3. Don’t burn! Six percent of the emissions during an inversion come from illegal wood burning, most of it recreational. Skip the yule log. It will benefit your health.
  4. Develop a Personal Action Plan. Our friends at Breathe Utah have a great online tool to help you plan and conserve energy this winter.

The human health risks from inversions come from our emissions. We can all play a part in helping out.”

Inversion: Day 3

NOAA’s Salt Lake Bureau’s latest measurements show the prolonged inversion episode intensifying. At 10 a.m., air monitors at Hawthorne Elementary measured PM2.5 at 16 micrograms per cubic meter (µg/m3). This is enough to bump the area into the “Moderate” (yellow) range in the Air Quality Index. At 35µg/m3, we move into the “Unhealthy for Sensitive Groups” range (orange). The thing to keep an eye on is the 24-hour average. Follow real-time monitor readings at

Today’s forecast keeps those 24-hour averages in the moderate range until Sunday, when we expect levels to move into the “Unhealthy for Sensitive Groups” range.

Unlike ozone pollution, which dissipates at night, PM2.5 sticks around until new weather conditions come in and mix the air at higher altitudes. The forecast doesn’t call for a change until later this month.”


Inversion: Days 4-5

2017 Salt Lake City inversion
Day 4

“If you are Christmas shopping, consolidate trips to prevent the air from getting worse. Let’s don’t let the air quality get so bad our kids have to stay indoors tomorrow.

In our valley, emission sources fall into three categories:

  1. Forty-eight percent from mobile such as cars and trucks
  2. Thirty-nine percent from area sources such as small businesses and homes, including wood burning
  3. Thirteen percent from point sources such as refineries, copper mines, and power plants

Do your part to reduce the 48 percent contribution from vehicles by limiting trips.”


Inversion: Day 6

2017 Salt Lake City inversion
Day 6

“Inversion conditions persist throughout northern Utah. This morning, it was cold enough to suspend tiny water droplets in the atmosphere, which created fog on top of the PM2.5 in the air. Conditions will continue for the next week at least.

While diurnal breezes change levels of PM2.5, the peaks have been rising, as have the 24-hour averages. The meteorologists at Utah DAQ forecast levels hitting “Unhealthy for Sensitive Groups” today.

This means people with heart and lung conditions need to take it easy. For the rest of us, help limit human-health risks by limiting the use of vehicles and, of course, do not burn wood.

Real-time monitoring and forecasts are available at and through the mobile app. You can download the app for free on your Android  or iPhone.”

Inversion: Day 7

“The fog has become more intense with the inversion. We are starting to see numbers spike for PM2.5 pollution in the area around the Hawthorne Elementary air-quality monitor. Like other meteorological conditions, these numbers fluctuate throughout the day and across the valley. Trends, however, show increasing PM2.5 levels across the Wasatch Front. If you or someone you know has a heart or lung condition, please limit outdoor exertion.

2017 Salt Lake City inversion
Day 7

You can help your health and your neighbor’s health by parking your car if possible, carpooling, and, of course, not burning wood.”

Inversion: Day 8  

“A simple glance out the window and it’s clear (pun intended) that the inversion and PM2.5 pollution is still with us this morning. #ActNow4CleanAir by limiting vehicle use and do not burn wood.

The bad news? We moved into the “Unhealthy” range for the 24-hour average in Salt Lake City last night. The good news? One-hour averages have come back down to “Unhealthy for Sensitive Groups” today.

What’s going on? Well, inversion ceilings change with diurnal winds. What is likely happening is that the ceiling of this inversion has lifted and conditions are improving on the valley floor.

Will the ceiling settle again? We will see as the day progresses. Follow our monitors at

Inversion: Day 9

2017 Salt Lake City inversion
Day 8

“If it looks better, that’s because it IS better. A weak front rolled through overnight and cleared out the fog and PM2.5 pollution. We are still in an inversion, so PM2.5 levels will climb again. The Wasatch Front is still under mandatory action restrictions.

What happened overnight: At 8 a.m., the 1-hour averages for PM2.5 had dipped to 18.6 µg/m3, or the “Moderate” range in Salt Lake City. The 24-hour average also fell to 39.6 µg/m3, or the “Unhealthy for Sensitive” range. Big improvements!

That 11 a.m. spike we’ve seen every day of the inversion hit as expected. Levels have now moved out of “Moderate” and back to “Unhealthy for Sensitive” range in Salt Lake City. All other counties are “Moderate.” Expect numbers to hover here until tonight. #ActNow4CleanAir! Little steps help.

Meteorologists say that a predicted front Friday night and Saturday morning might improve conditions temporarily. That high pressure system, however, is still sitting over northern Utah, and inversion conditions are forecast to stick around.”

Inversion: Day 10

“We aren’t out of the woods yet. The inversion is still holding on, with the soonest relief possible coming on Saturday. The good news? Those high-level cirrus clouds you see above the inversion are indicators of a front moving into the area.

Saturday’s front will change the temperature profile and allow for greater atmospheric mixing, which will move the PM2.5 pollution off the valley floor. For now, though, mandatory restrictions are still in place. Please refrain from burning wood.

The numbers from 10 a.m. show the mid-day spike in PM2.5 is right on schedule. The 24-hour average for Salt Lake City is in the “Moderate” range for some of the best #AirQuality in the last week. All other counties are reading “Moderate.”

#ActNow4CleanAir is our hashtag mantra to persuade Utahns to do their part to help keep our air clean so everyone can breathe easier. Visit UCAIR for more tips on how you can reduce pollution, not just during inversions, but every day.