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Why is the air so bad during winter, and what can we do about it?

Utah inversion season

Inversion season is back.

As you prepare for holiday festivities and time with friends and family, you may have noticed what looks like a fog blanketing our airsheds. This peculiar haze that occurs annually during Utah’s winter is known as inversion, and it isn’t good for our health.

 

In some parts of Utah and other regions, winter is a time when air quality can improve. Higher levels of precipitation can help clean the air of pollutants, and winter storms help push them out of airsheds. The Wasatch Front, however, is surrounded by multiple mountain ranges that prevent winter storms from easily moving pollutants out of the air we breathe during inversions.

What are inversions?

During most of the year, warm air is closer to the earth’s surface, and cold air is higher up in our atmosphere. During winter inversions, these temperatures are flipped. Cold air is trapped under a layer of warmth, and fine particulate matter pollutants (PM2.5s) get trapped in the cold layer we breathe as inversions progress.

The Division of Air Quality has a daily forecast for air quality conditions in Cache, Carbon, Davis, Duchesne, Iron, Salt Lake, Tooele, Utah, Uintah, Washington, and Weber/Box Elder counties. The Air Quality Index measures how unhealthy the air is at any given time and what groups should take precautions. View here. 

What are particulate matter pollutants?

“Particulate matter (PM), also known as particle pollution, is a complex mixture of small solid particles and liquid droplets in the air… Primary particulate matter is emitted directly from construction sites, wildfires, wood burning, gravel pits, agricultural activities, and dusty roads. Secondary particulate matter is formed in the atmosphere through complex chemical reactions. PM2.5 precursors such as nitrogen oxides (NOx), volatile organic compounds (VOCs), sulfur dioxides (SO2), and ammonia contribute to the formation of secondary fine particulates.” Source: Utah Department of Environmental Quality Division of Air Particulate Matter Overview

PM2.5 particulates are fine, inhalable particles or droplets with a diameter of 2.5 microns or smaller. These fine particulates, about 30 times smaller than the width of a human hair, can travel deeply into the lungs and cause both short-term and long-term health effects.

 

PM10 is particulate matter 10 microns (μm) or less in diameter. It is a mixture of materials, including soot, metals, salt, and dust. It can also be inhaled into the upper airways, causing irritation and health problems.


Learn more about the different types of particulate matter here.

Emissions come from three primary sources – vehicles, area sources, and industry. Cars, trucks, and heavy-duty vehicles are the biggest contributors to our air quality problems. Area sources, including buildings, homes, development projects, wood burning, and agriculture, collectively comprise the second largest source of emissions. Finally, industry, such as refineries, mines, power plants, and waste facilities, comprises the smallest overall source of emissions. However, significant state and federal regulations have helped them reach their current levels.

In the short term, exposure can irritate the lungs, making it difficult to breathe and worsening symptoms of those who have respiratory diseases, including asthma, bronchitis, and lung cancer. Spikes in PM levels correspond to increased hospitalizations and emergency room visits. Long-term exposure can cause the development of respiratory diseases, including asthma and emphysema, as well as heart conditions, such as congestive heart failure and coronary artery disease. Exposure to particulate matter contributes to premature mortality and reduced lung development in children.  



What steps can we take as individuals to clean our air?

C: CARPOOL WHENEVER POSSIBLE

L: LIMIT COLD STARTS AND COMBINE TRIPS

E: ENGAGE IN CLEAN AIR ADVOCACY

A: ACCESS PUBLIC TRANSPORTATION

N: NAVIGATE SMOG RATINGS AND ENGINE TYPES

A: AVOID UNNECESSARY COMMUTES

I: IDLE LESS OR NOT AT ALL

R: RIDE A BIKE OR WALK