As 18-year-old Wyatt Johnson prepared for AP tests in his senior year of high school, he wasn’t the only busy one at his crowded West Valley City home. The family of six ran between activities, household chores, jobs and all the hubbub that comes with raising four children.
At school, Johnson became familiar with how the often bad outdoor air quality in West Valley City made a mark on his community’s environment and health. Last year he entered an art competition to market solutions to the valley’s air pollution concerns. This year, he monitored the issue at the most hyper-local level he could find: his house.
Johnson learned about how small particles from car exhausts, neighboring refineries and even the Great Salt Lake were part of a big air pollution problem that plagued Utahns with asthma and other health concerns. But, what was happening indoors, where he and most people spend the majority of their time? Would those particles sneak into the family’s lungs while Wyatt was drawing or while his siblings played video games?
Or was his family in control of the air they breathed in their own home?
In four Salt Lake Valley households, including Johnson’s, residents installed indoor air-quality sensors built by Columbia University’s Brown Institute for Media Innovation during May and June. The two months predated Utah’s above-average wildfire season and no inversions occurred.
With a small fan to pull in air samples, and scattered light, the device estimated the mass concentration of PM2.5, a mixture of tiny particles in the air, and monitored carbon dioxide, temperature and humidity for about two months. Throughout the experience, Wyatt Johnson recorded his reflections and shared them with Reaching for Air, a multimedia series by KUER and The Salt Lake Tribune,.
“I'm realizing a little more that indoor air quality is a lot more important than I really gave it credit for,” Johnson said at the beginning of the study. “I always thought that it was all about, like, smog outside or whatever, and the terrible air that we breathe outside, but I thought a little less about what I'm breathing when I'm inside my house.”
As the sensor sat in the living room, Wyatt’s mom Rebecca Johnson saw the lights indicating the PM2.5 levels inside the house sometimes reached three digits. She became as invested as her son in tracking the roots of the issue. Many of those times there wasn’t a clear explanation for the ranges, but after the study, the family made changes to address the particles that live among them.
Is bacon the culprit?
This year, in the middle of a commitment to not indulge in fast food, the Johnson kitchen has seen more steam and sizzling hot oil from the family’s pots and pans.
But, in that quest, a greasy, sweet-and-salty breakfast addition made Johnson’s sensor reach numbers it had never shown.
“There was a huge spike near 200 (µg/m3) at about 7 p.m. tonight when my mom was making bacon,” Johnson said on May 20, the day he saw the highest level of PM2.5.
That range is considered “very unhealthy.”
“And then my mom turned on the fan, and then it dropped all the way back down again,” Johnson said in his entry.
Each time he reflected on the three worst PM2.5 spikes, Johnson knew what had been on the breakfast menu.
“That was because we were cooking bacon inside, we were cooking bacon for breakfast burritos. So I know exactly what that one was,” Johnson said on May 30 about a 170 µg/m3 spike – the third-highest level captured that month.
It took about 15 minutes, Johnson said, before the PM2.5 levels dipped down to about 40 µg/m3. While 40 µg/m3 is still considered “unhealthy for sensitive groups,” it was a significant improvement.
After Johnson submitted his last recording, his mom wanted to clarify that fried food isn’t something they eat frequently. However, she said, seeing the numbers skyrocket as the kitchen and living room filled up with smoke made her better understand what it means to breathe in the particles suspended in the air.
“It's in the back of my mind a lot. So I think it's changed the way that I fix food for our family, probably to the point where it's even less frequent than we already infrequently were having it,” Rebecca Johnson said of the fried foods.
She also started cooking with an air fryer instead of oil, which she said makes a significant difference.
How is this affecting Utahns?
Typically, people spend more than 90% of their time indoors, so it’s an important proportion of the regular daily exposures to air quality. And the main drivers of poor indoor air quality are mostly found within a building’s walls.
“Any type of solid fuel burning in the house, and smoking — those are the two biggies,” said Kerry Kelly, an associate professor in chemical engineering at the University of Utah. She has conducted similar experiments, but at a much larger scale.
Cooking with natural gas or oil, frying, and other personal activities (such as vaping) are also some predominant sources of PM2.5. Then, there are outdoor factors that could contribute to indoor pollution.
A study conducted in buildings at the University of Utah campus found that of all outdoor pollution events — including dust, wildfires and inversions — wildfire smoke tends to be the biggest cause of poor indoor air quality, Kelly said.
Dust particles are pretty big, so most filtration systems will do a good job removing them, she said. And inside temperatures and relative humidity make inversion particles dissociate.
Also, certain HVAC systems that use airside economizers, while great for efficiency during hot months, can bring in more particles from wildfire smoke, the study found.
There are many factors that contribute to indoor air quality, Kelly said, including the age of the building, poor filtration, whether or not the people inside smoke, and whether or not they use natural gas for their stove or an electric one.
The one upside is that most people can do things to mitigate indoor pollution.
A fan with a HEPA filter taped to it can help absorb some of the particles for households on a budget, Kelly said, as opposed to purchasing sleeker air filter units.
“Filtration is good, especially if you've got one of these extended events, like a wildfire event,” she said.
Other fixes are even lower maintenance.
“If you've decided you're frying a bunch of bacon, open the windows. It's a great solution.”
Editor’s note: This story is part of Reaching for Air — a collaboration of The Salt Lake Tribune, KUER, Utah News Dispatch and the Brown Institute for Media Innovation, which explores air quality along the Salt Lake Valley’s west side.
The indoor air quality project and sensors were designed by Todd Whitney. Statistical Analysis was by Yue Zhao.
