Can you improve air quality in your home? These Utahns let indoor sensors track their daily life. Here’s what they learned.

Salt Lake Valley’s west-siders expect bad air. Winter inversions hit them harder than the east, with historic redlining exacerbating the issue.

But how much do hazy conditions outside affect the air flowing inside homes? A handful of residents decided to experiment.

Four Salt Lake Valley households installed indoor air-quality sensors built by Columbia University’s Brown Institute. With a small fan to pull in air samples, and scattered light, each device estimated the mass concentration of PM2.5 and monitored carbon dioxide, temperature and humidity for about two months.

Every day, participants recorded a voice diary, offering intimate glimpses of their lives in the places where they spent most of their time. This is what they learned.

A quest for health answers

In Tegan Spangrude’s Rose Park home, those she loves have plenty of space to roam and be cozy.

Snowman, a tall white-and-gray sheepadoodle, stumbles with excitement when guests knock on the front door, running in place while Spangrude holds his leash. There’s also Koleeky, a 42-year-old African gray parrot who’s shy, but can make his voice heard as he gets more comfortable. What’s on the mind of Garth, her scorpion living inside a little terrarium, remains a mystery.

Outside Spangrude’s house, there’s a tight community in one of the state’s most ethnically-diverse neighborhoods, with quaint bungalows, quirky parks and access to the Jordan River Trail. There’s also a manicured garden, reflective of the life she and her husband, Dallen Brown, have built inside. Among many lush plants and some heirlooms, the couple has aimed to start a family.

As a nurse, Spangrude had been curious about what gave her outdoor air a metallic, dirty taste when the smoke traveling downwind from refineries in neighboring cities is particularly visible. But what prompted her to participate in the study was something that made her teary-eyed.

“I had a miscarriage,” she said. “And it was really hard, you know, and there was a lot that went through my mind.”

After learning that there is a correlation between poor air quality and pregnancy outcomes on the west side of Salt Lake City, she wondered if the air she breathed contributed to her loss. A University of Utah study published in 2018 surveyed more than 1,300 women and found a 16% higher risk of miscarriage “following short-term exposure to elevated air pollution.”

“Could the air quality have contributed to this? Ultimately, that could be true,” she said, sitting at her dining table. “But the fact is that a lot of people have miscarriages, and for most people, there’s nothing that you could have done better. You couldn’t have eaten more vegetables, you couldn’t have lost more weight, you couldn’t have done anything different, and the outcome would have still been the same.”

After participating in the project, Spangrude felt more at ease, knowing that sometimes — despite the grit she felt on her teeth outside, drifting from the nearby quarry — the sensor inside her home didn’t register major spikes.

In May, Spangrude’s sensor captured an average of 13 micrograms per cubic meters (µg/m3) of PM2.5, which is considered to be “good, almost moderate.” The lowest registered level was 11 µg/m3 and the highest was 639 µg/m3, in the “very unhealthy” range.

That day, while sauteing mushrooms and kale, she made the mistake of keeping oil on the heat for too long, burning it.

“I was shocked to look over and see my PM2.5 sensor had shot up to 639 (µg/m3), so that was really interesting for me to see,” she said, “just to put into perspective how good 11 and 12 (µg/m3) is.”

But the worst PM2.5 level happened on June 9, when some fish burned in her oven, filling the main level with smoke. That day the sensor went into the four digits, reaching 3,631 µg/m3, a “hazardous” level.

The chaos of everyday living with loved ones comes with its dose of indoor air pollution, she realized, but it isn’t that bad. Now, Spangrude is less afraid and more willing to open up the doors and windows for an air reset.

[”Reaching for Air”: Hear the voices of west-side residents in our interactive presentation. Check out the west side’s air quality in real time on our map.]

The bigger picture

Kerry Kelly has conducted similar experiments, but on a much larger scale. She works as an associate professor in chemical engineering at the University of Utah.

The good thing about cost-effective sensors, she said, is that they do give a relatively adequate measure of PM2.5 concentrations. The challenges, however, are that because they are small, they aren’t great at measuring dust, and many of them can overestimate readings by 1.5 times. However, there are correction factors to get more accurate levels, and the Brown Institute sensors were meticulously calibrated before being sent to these homes.

The four participants recorded their daily diaries during May and June. The two months predated Utah’s above-average wildfire season, and no inversions occurred.

Elevated levels of particle pollution are associated with numerous unhealthy effects, Kelly said. Typical ones include asthma, but other repercussions can include premature death, heart attacks, strokes and preterm birth. Particle pollution is also associated with loss of IQ points in children and decline in older adults’ cognitive function.

That’s “based on epidemiological studies, where people are looking at outdoor levels of particulate matter and correlating it with emergency department visits, premature death, heart attacks, strokes,” she added.

However, people typically spend more than 80% of their time indoors. 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,” Kelly said.

Cooking with natural gas or oil, frying, and other activities (such as vaping) are also some predominant sources. Then, there are outdoor factors that could contribute to indoor pollution.

A study conducted in buildings on the U. 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.

Is bacon the culprit?

As 18-year-old Wyatt Johnson prepared for AP tests his senior year of high school, his parents ran in and out of their crowded West Valley City home between household chores, their jobs and raising four children.

At school, Johnson became familiar with how the air quality in West Valley City affected 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.

“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.”

This year, in the middle of the Johnson’s family commitment to not indulge in fast food, the Johnsons’ kitchen saw 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 their 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. “And then my mom turned on the fan, and then it dropped all the way back down again.”

Each time he reflected on the three worst PM2.5 spikes, Johnson knew what he had for breakfast the next day.

“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 in an audio entry on May 30, talking about the third-highest level captured that month.

After Johnson recorded his last entry, his mom, Rebecca, 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,” she said of the fried foods.

She also started cooking with an air fryer instead of oil, which makes a significant difference, she said.

Smoking inside

Driving to her job in Draper from her home in Magna, Cheyli Sylvester said she sees one of the reasons why she carries an inhaler most of the time. The Oquirrh Mountains turn into a smoggy blur in her rearview mirror, while the sky turns into a clearer blue every mile away from her west-side home.

As a data scientist, she said it became a casual mission to determine whether the three-bedroom house where she lives with her girlfriend in any way reflects the outside environment she shares with some of the biggest polluters in the Salt Lake Valley.

“I love doing science. Usually I’m the one that crunches the numbers at the end. So it’s very interesting to be the one that’s making the numbers,” she said after sending her last recording.

She said she was curious whether the air quality inside her home was contributing to her asthma. However, every day that went by, she grew more comfortable.

“Originally, I was really nervous that the air quality inside was going to be really bad and that I was going to have to take large measures to improve my everyday breathing,” Sylvester said. “The good news is that it didn’t scare me that much.”

After work, Sylvester unwinds by cooking dinner and smoking. As the oil heats in her pans, it releases a sometimes faint fume, while the very visible lines of smoke from her puffs travel across her kitchen.

That’s when most of her PM2.5 spikes happened.

One day she saw PM2.5 levels rise to around 60 µg/m3 only from smoking, she said. Other times, with the windows open, those levels reached 40 µg/m3.

Aside from smoking, some of the worst PM2.5 spikes came from using dry shampoo and other aerosols, reaching about 20 µg/m3, even when she used them in a different room.

While she realizes that smoking isn’t good for her lungs, she said it helps her sleep and doesn’t foresee stopping anytime soon.

Ventilation was key, Sylvester found during the first week of the study. The cooking and smoking-related spikes diminished and the particles dissipated faster with a fan blowing and windows open. Opening the windows during spring days in Magna had another effect –– on her mind.

“The vibe is good, like birds chirping, the breeze coming in — even something silly, like the road traffic noise,” she said. “It’s kind of nice having the outside inside. … I don’t know how much that attributes to the air quality, necessarily, but it definitely makes me feel better.”

‘That’s gourmet’

Allyson and Anthony Galarza live in a comfortable cottage on a quiet street in Salt Lake City’s Wasatch Hollow neighborhood. They raised their daughter there, along with their small, vocal dog, Bella. It’s where Alysson, an art teacher at Granger High School, creates her original artwork and Anthony tests his creativity with new recipes in the kitchen.

When Anthony moved to Utah from Montana, he noticed the thick coats of gray that turned the mountains – normally visible from his home on the east side – unrecognizable. The visual reminder of the polluted valley air prompted him to buy air purifiers and frequently change the air filters inside the house. He even cleans the HVAC system.

“I kind of wondered if that was maybe a little overboard,” Alysson said about her husband’s air purification routine. “But it’s not. It’s great.”

The sage green sensor – which the Galarzas named Kermit, after the Muppets character – picked up the PM2.5 that circulated around their home.

Overall, their indoor air quality was consistently in the “good” range, around 12 µg/m3 and below. It would sometimes spill over into the “moderate” range of 12-35 µg/m3 and rarely hit “unhealthy” levels of 55-150 µg/m3.

But when those stark spikes in PM2.5 did occur, they were sure to notice and do something about it.

When the Galarzas made some renovations to the house, they opted to pay “quite a bit more” to install a gas line in the kitchen. Anthony enjoys whipping up meals and Alysson said they “loved the idea of cooking over a flame.”

“That’s gourmet,” Alysson said with a chuckle.

But after having the sensor in their home, they recognized a pattern they couldn’t deny. Every time they lit a burner on their stove, even to cook something simple like a quesadilla, PM2.5 would surpass the average levels they experienced.

What they were cooking had the power to drastically impact their indoor air quality.

On May 4, Anthony spent a “prolonged time” cooking that Saturday in a pan on the stovetop. During that time, their PM2.5 hit 113 µg/m3, which was also the highest level of pollution recorded for the entire month.

Breakfast foods seemed to create the most pollution, according to the radio diaries. To celebrate Anthony’s birthday on May 29, he requested breakfast for dinner. Alysson turned on the stove to cook “all the things,” including bacon, hashbrowns and eggs.

Lo and behold, “yup, it [PM2.5] spiked,” she said in an audio entry.

As summer sits in the rearview and snow begins to sprinkle down in the mountains, the Galarzas have established new cooking habits on the gas range thanks to their participation in the project.

“We definitely did start using the hood preemptively. If I knew I was going to use the gas range, I would turn the hood vent on before I turned the range on, and then open the windows up before I started cooking,” she said, “because once we really noticed the pattern, it was undeniable.”

But Anthony is thinking about doing the unimaginable: ditching the gas range altogether. “‘I’m going to look for a government rebate for an induction oven,” he said.

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 done by Yue Zhao.

Alixel Cabrera is a reporter at Utah News Dispatch covering the status of diverse Utah communities, energy, growth and education. She previously worked as a west side reporter at The Tribune.

Saige Miller is a political reporter for KUER, NPR Utah and co-host of KUER’s politics podcast “State Street.” She previously worked as a reporter and producer for The Tribune’s Innovation Lab.