Plotting pollution: Researchers use TRAX to monitor air quality around Salt Lake valley

Posted at 9:50 PM, Feb 10, 2016
and last updated 2016-02-10 23:50:59-05

SALT LAKE CITY -- How bad is the air where you live? If you are in one of Utah’s valleys during the winter inversion season, a few miles can make a world of difference.

“We’d really like to be able to know what is the air quality spatially across the whole valley,” said Dr. Logan Mitchell, PhD.

Mitchell is the atmospheric scientist behind a project that put an air quality monitoring station on top of the red line TRAX train.

“There’s no other city in the United States that is doing something quite like this," he said.

Currently, the readings used to determine air quality warning levels in the Salt Lake Valley all come from one monitoring station at Hawthorne Elementary at 1675 South 600 East. Mitchell’s research is putting numbers behind the long-held belief that air quality differs depending on where (and often how high in elevation) you are in the valley.

Results from a multi-day inversion in January 2015 may be the most telling. At the start of the train’s journey at the Daybreak station in South Jordan, average PM2.5 particulate levels were 30 micrograms per cubic meter. 35.5 is the level that triggers the ‘Unhealthy for sensitive groups’ warning from the Utah Division of Air Quality.

A few miles down the track at the Murray Central Station, there was a significant jump. Average levels were around 55 micrograms per cubic meter, jumping two levels on DAQ’s scale to ‘Unhealthy’. Small changes can produce dramatic impacts on health concerns.

“If you increase the particulate level by 10 micrograms per cubic meter, you end up increasing the rate of heart attacks by about 4 percent,” said Dr. Robert Paine, a Pulmonary Physician at the University of Utah Hospital.

Based on Mitchell’s research, elevation appears to be a key factor in determining pollution levels during an inversion. However, it’s not the only factor. The Daybreak station and the last station at the University of Utah are roughly the same elevation. However, levels measured a few points higher at the University.

“There is a danger of simplifying it too much, that these maps change over time, and we have to realize that, that’s right there where there sensor is, a block away may be something different,” Paine said.

Proximity to traffic corridors and topography may also play a role in the complicated interactions that determine air chemistry. However, Mitchell says one thing is clear.

“Turns out the biggest impact is all of us together,” Mitchell said. “The majority of particulate matter is from cars, cars and trucks driving around.”

While his research is broadening our understanding about how pollution spreads across the Salt Lake Valley, it has limits. The TRAX train travels a fixed route, and a few blocks one way or the other, could make a major difference.

You can view live results from the sensors on the TRAX by clicking here.

To see what the current warnings from the state regarding air quality, click here.