GRAND JUNCTION, Colo. - Black blotches surround the mouth area of the silk balaclava (a ski mask-like head covering) that Grand Junction resident Karen Sjoberg wore while walking her dog every day last winter.
"It shows what I would have breathed in," Sjoberg said, who suffered a bad cough for more than a month in December and January.
Air quality in Grand Junction was worse than Denver's for a period in January when inversions trapped ozone and particulate-laden air in the valley. Inversions occur when cold air settles down, and warmer air above acts as a lid, keeping pollutants from dispersing.
"We're surrounded by mountains. That natural geography is a perfect set-up for inversions to occur," Mesa County Air Quality Specialist Ed Brotsky said. "It can last days or weeks.
"During this time, air pollution is generating and there's no way for it to escape - until warmer weather or a storm pushes it out."
Springtime brings other issues when residents and farmers begin burning weeds, brush or fields, an old-time agricultural practice that adds particulates to the air; particulates are one of three "criteria pollutants" that Brotsky monitors regularly.
Greg and Joyce Isaman recently returned to the Grand Valley after spending a month out-of-state because Joyce, who has asthma, finds breathing difficult once the official burn season begins in March.
"We're basically forced to leave if we want to stay healthy," Greg Isaman said.
Isaman said he's not as sensitive as his wife and some of their friends, but when people set fire to plant material his eyes water. And, he's been forced to go inside at times when his lungs start to hurt and his eyes burn.
Redlands resident Tom Kelly said he often notices a blue haze hanging over the valley during the spring burn season, March 1 through May 31. Burning is also allowed in the fall, Sept. 1 through Oct. 31.
During those periods, fire protection districts issue permits that allow residents to burn compostable materials such as dry weeds, garden waste, and tree, shrub or brush trimmings less than one inch in diameter.
Active "for profit" farmers and ranchers can burn without obtaining a permit.
As the valley's population increases and pollution grows from all sources, many residents say the practice of burning weeds and other brush is outdated, unhealthy and unnecessary.
"It seems like our city fathers allow polluted air in order to not ruffle feathers," Kelly said. "The burning is done out of convenience and tradition.
"Some say 'we were here before you,' but it's immoral to do something you know to be harmful to human beings," said Kelly, who moved to Grand Junction with his wife 10 years ago from Gunnison where they lived for 29 years.
Tri-River Cooperative Extension agent Bob Hammond said burning is a "traditional, cheap and effective way" to get rid of weeds and other brush.
As a small acreage owner, Hammond said he burns residue such as tree trimmings and fallen trees from his land.
"You got to clean it up. It's cheaper, quicker, easier than loading it up in a truck and bringing it to the compost facility," Hammond said.
At the same time, Hammond admits that "reducing the amount of burning is an achievable goal."
Fruita farmer John Justman, who's also a Mesa County Commissioner, said he burns less than he did 40 years ago when he first started farming, but "still, it's a necessary evil for agriculture to get rid of the weeds in front of the ditches," he said.
"I understand people are against it, and I can kind of appreciate that," Justman said. "But with the price of diesel fuel, and several trips across the field with a tractor, you're talking about quite a few dollars," to plow under crop residue.
Fine particles (particulate matter 2.5, or PM 2.5) are Mesa County's most pressing concern regarding air quality in the Grand Valley, Brotsky said.
Particulates refer to the size, not the source of the toxin. For example, PM 2.5 refers to fine particulate matter that measures two and a half microns; PM 10 indicates a coarser particle that measures 10 microns in diameter. (A human hair typically measures at about 60 microns.)
The toxic specks of dust pose a greater health risk because the tiny particles can penetrate deeply in the lungs, and can be cancer-causing, depending on the source, Brotsky said.
Agriculture and residential burning are one source of particulates, along with vehicle emissions and smoke from woodstoves and forest fires.
Monitoring equipment gives hourly readings of particulate matter present in the Grand Valley's air. For regulatory purposes, Brotsky collects air samples for state laboratory analysis every three days.
Mesa County was headed toward noncompliance of air quality standards from 2008 to 2010; then came two good years where pollution was less, bringing the average measurement down to acceptable levels, Brotsky said.
Then came 2013, a particularly bad year, he said.
"There were multiple days in January that we were at a level known to impact human health. We violated the standard for several days."
Levels must exceed allowances during a consecutive three-year period for a city to become non-compliant.
"The combined actions of thousands of people going about their business, it's hard to get it under control. It's probably only a matter of time before vehicle standards (will be enforced) if we keep going about business as usual," Brotsky said.