Air Quality Compliance Outreach Newsletter Volume 5
November 2020

PM2.5

PM2.5 is the main component of Utah’s wintertime air pollution. PM2.5 refers to microscopic particles, or particulate matter (PM), that have a diameter of less than 2.5 micrometers—smaller than pollen and most bacteria.

During an inversion, temperatures increase with increasing altitude—the inverse of what normally happens. The warm inversion layer then acts as a cap and stops atmospheric mixing. This holds PM2.5 near the ground and causes the smog that occasionally covers the valleys of Northern Utah.

Sources of PM2.5 are broken down into three categories: point sources, mobile sources, and area sources. Point sources (13 percent of a typical inversion) are large stationary industrial or commercial facilities. Mobile sources (48 percent of a typical inversion) are non-stationary sources such as vehicles, trains and aircraft. Area sources (39 percent of a typical inversion) are smaller stationary sources. These include emissions from home heating, smoke from wood burning, and emissions from small businesses like restaurants and dry cleaners.

Ozone

Ozone is formed when oxides of nitrogen (NOx) and volatile organic compounds (VOC) break apart in the presence of sunlight and high temperatures and recombine into new structures, creating ozone. Ozone at ground level is a harmful air pollutant that damages human health and vegetation. It is a key ingredient in summertime smog and haze.

Approximately 90 percent of atmospheric ozone occurs naturally and is located in the stratosphere to protect the earth from the sun’s ultraviolet rays. The remaining 10 percent of ozone is located at ground level and is a result of compounds emitted from automobiles, industrial facilities, and household products.

Breathing ozone can damage lung tissue. Low amounts can cause chest pain, coughing, shortness of breath and throat irritation. Ozone may also worsen chronic respiratory conditions and compromise the ability of the body to fight respiratory infections.

PM10

Like PM2.5, PM10 is the measurement of particulate matter. These are the larger particles in our air. Commonly, these particles are things like dust and coal particles from power plants. Sources of PM10 include crushing or grinding operations, wind-blown dust and dust stirred up by vehicles on roads. PM10 also comes from combustion in car engines, home heating and industrial sources.

Exposure to PM10 can cause a number of health problems including coughing and wheezing to asthma attacks. PM10 can also aggravate lung and heart conditions.

NOx

Oxides of nitrogen, or NOx, are poisonous, highly reactive gases. These gases form when fuel is burned at high temperatures. Sources of NOx pollution include automobiles and non-road vehicles (planes, boats, etc.) as well as industrial sources such as power plants, boilers, and turbines. When NOx reacts with VOCs near ground level on hot summer days, it produces ozone. NOx is also a direct component of PM2.5 pollution.

VOC

Volatile organic compounds are released into the air mostly during the manufacture or use of everyday products and materials. Some common sources or VOCs include the fumes from fuels, personal hygiene products, cleaning agents, paints, and other solvents used commercially or in homes.

When VOCs mix with sunlight and NOx, ozone is formed. In the wintertime, VOCs combine with other chemicals to form ammonium nitrate, a precursor to the formation of PM2.5.

CO

Carbon monoxide (CO) can be lethal in high concentrations. The concentration of CO in the air depends on local weather conditions and the number of automobiles in the area. High levels of CO can have acute health effects on humans by reducing the supply of oxygen in the bloodstream. Combustion emissions are the primary source of CO in our air. This can come from automobiles, home heating, or other sources.

SO2

Sulfur oxides (SO2) are gases produced by burning sulfur. All fuels used by humans (oil, coal, natural gas, wood, etc.) contain some sulfur, and during the combustion process, sulfur reacts with oxygen to form SO2. The primary source of sulfur oxides is the burning of fossil fuels, particularly coal. Since the introduction of catalytic converters in automobile, SO2 has mostly disappeared from Utah’s air.

SO2 can combine with particles and moisture in the air and contributes to the formation of acid rain by transforming into sulfuric acid in the atmosphere. Acid rain can damage lakes and aquatic life, building materials, and plant life.

Wood Smoke

Wood smoke, or solid fuel smoke, is the product of incomplete combustion, which releases VOCs, NOx, and fine particulates as the wood/solid fuel burns. In addition to the direct PM2.5 emitted from burning, VOCs and NOx react to form PM2.5. During inversions, these particles build up in the valleys, sometimes reaching unhealthy levels.

Fireworks

Utah’s Division on Air Quality regularly sees significant spikes in concentrations of both PM10 and PM2.5 associated with fireworks displays. These spikes occur in the location of professional displays and also areas surrounding smaller gatherings of neighborhoods or families celebrating the holidays with displays of their own.

Those most affected are the young, the elderly, and those sensitive individuals with respiratory conditions.