Researchers say air pollution is getting inside, recommend MERV 13 filter

SALT LAKE CITY — In Utah, we know a lot about our outdoor air quality because we’ve talked about it as a community and examined the impacts on our health. We know a lot less about the air quality inside our homes, schools and buildings. Salt Lake City Mayor Erin Mendenhall got that conversation started Tuesday.

Mendenhall has said she is committed to improving Salt Lake City’s air quality, so she convened an Indoor Air Quality Summit to get that conversation moving.

Such a great morning with @slcgreen at the Indoor Air Quality Summit! If we had Transit week last week, let’s keep the ball rolling and call this air quality week! pic.twitter.com/mkWn2OXRVD

— Mayor Erin Mendenhall (@slcmayor) August 2, 2022

“Outdoor air quality is an indoor air quality issue,” said Nicolas Rice, corporate industrial hygiene manager at Intermountain Healthcare.

That’s a critical takeaway from researchers who presented their latest work on the indoor health impacts of Utah’s wintertime particulate pollution, summertime ozone pollution, and pollution from wildfires.

“Just under 90% of our time over the life is spent inside,” Rice said.

The air we breathe inside relates to outdoor air quality because studies show that only half of outdoor pollution is buffered by our buildings or homes, and that percentage varies a lot from building to building. But a lot of pollution gets inside, which is where we live the vast majority of our lives.

“Since we spend about 90% of our time indoors, it is paramount for us to be really most concerned about the pollution exposure that we receive while we’re inside a building, whether it’s our home or a commercial building,” said Dr. Daniel Mendoza, a research assistant professor with the University of Utah Department of Atmospheric Sciences.

Mendoza has asthma, so his research is personal for him. It shows that Utah’s wintertime particulate pollution, formed in the cold, does not hold up in a warmer environment inside.

“Those stable environmental conditions that were there for it to be formed no longer exist,” he said.

So, only 20% of that PM 2.5 pollution makes it inside. But the pollution from wildfire smoke is different.

“During wildfires, about 80% goes inside. Why? Because those smoke particles, not only are they smaller, but they are also real particles. They are going to be stable regardless of the environment,” Mendoza said.

Using an air filter with a MERV rating of 13 or higher can filter out as much as 85% of the indoor pollution, according to the research.

“Today’s summit is the beginning of a long conversation that we’ll be having on what the public can do and what we can do as institutions to help protect indoor spaces,” said Debbie Lyons, sustainability director for Salt Lake City.

Researchers agree there is a lot more to be done on public policy and to be shared as the community learns more about the impacts of indoor air pollution.