Inversion season is here! What can we do?

November 1 is the official start of inversion season along the Wasatch Front and it certainly feels like  winter is settling in around us!

But what exactly is an inversion? This natural phenomenon occurs when a high-pressure system is setting up, trapping cold air on the valley floors with warmer air above it. This warm air also traps all our pollution with the cold air, keeping it contained in the valley until the inversion breaks. 

What causes an inversion? 

Meteorologists on the news and the Utah Division of Air Quality will  warn you in advance before an inversion happens. Here are some signs that you can keep a look out for: 

• Calm winds: this reduces the natural mixing of air temperatures. 
• Clear skies: this increases the rate of cooling for air close to the ground. 
• Long nights allow the cooling of the ground to continue over a longer period of time, resulting in a greater decrease in temperature near the surface. 
• The sun is lower on the horizon during the winter, so it supplies less warmth to the earth’s surface and more to the atmosphere. 

In Utah, our inversions often occur right after snowstorms due to the increase in cold air near the ground and the clear skies warming up the upper atmosphere and acting as a lid to the cooler air below. 

Inversions are meteorological events that are common in mountain/valley geographies with our weather patterns.  When you pair inversions with human activity, you often wind up with pollution that sticks around.  Here along the Wasatch Front, a significant source of pollution comes from transportation(roughly 50%), as well as our homes and buildings (roughly 35%). That means each of us can make a difference to our air quality. 

What can you do? 

• Drive less! Aiming for more car free days is one of the most impactful activities we can do to help improve our air quality. Take the bus, bike, walk, or work from home if you have the option! Check out this link to see if you’re eligible for a Hive Pass, Salt Lake City’s discounted transit pass. 

• Be idle free! Vehicle exhaust makes up nearly half of the air pollution on the Wasatch Front during a winter day– that’s huge! But many of us must still drive at least some of the time. So when you do drive, drive smarter to save pollution. Limit your idling to two minutes, or not at all. Learn more about Salt Lake City’s Idle Free Ordinance.  
• Skip the woodburning! Burning wood contributes to particle pollution, carbon dioxide, nitrogen oxides, and other hazardous compounds. These pollutants not only harm our outdoor environment, they also contribute to indoor air pollution. If you can’t skip it all together, avoid wood burning on bad air days and during inversions, and consider building a DIY air purifier, or buying one to protect your indoor air! 
• Go electric! Switching to electric appliances, heating/cooling systems, and vehicles is a direct way to reduce air pollution.  
• Sign up for air quality alerts! One of the best things you can do is be informed- the Division of Air Quality sends alerts through their apps for iOS or Android so you can be up to date on the situation surrounding our air. 

What is Salt Lake City doing? 

There are a lot of historical initiatives, ordinances, and programs we’ve developed over the years to improve air quality. Take a look at them on our air quality page. 

Most recently, here is a small sample of what the City is working on to help clear the air: 

TRANSPORTATION: 

• Giving free UTA transit passes to all students and staff in the Salt Lake City School District! This initiative was funded by the City Council and other partners this budget year and will provide equitable transportation access to all of our city’s schoolchildren, while also helping reduce emissions. 
• Salt Lake City continues to invest in bike lanes and active transportation infrastructure when resurfacing Salt Lake City roadways. Check out Transportation’s list of projects here. 
• Investing in cleaner vehicles: Over 25% of our fleet is comprised of clean vehicles – meaning all-electric, hybrid, or Compressed Natural Gas, and at the Airport, this number is reaching 40%.  The Airport also recently purchased 11 all-electric Ford-150 Lightnings that they expect to have delivered soon!  
• The City’s goal over the next couple of years is to ensure that all sedans/passenger vehicles we purchase for our fleet are electric. Then we will target pickup trucks and the cleanest options for our largest equipment when it is replaced.  
• Salt Lake City is in the process of assessing where to install more public electric vehicle (EV) charging stations to support the community-wide transition to cleaner vehicles. The City currently has 20 Level 2 public stations with 2 ports each.  
• Providing other incentives to support the transition to electric vehicles, like free parking at City meters for the cleanest vehicles as part of the “Green Sticker” program.  
• We are in the process of proposing requirements for new multi-family developments to have EV-ready parking – meaning that as the EV market continues to grow, it will be more cost-effective and easy for EV stations to be installed, because the wiring and capacity will already be sufficient in new construction. Look for this update to come before City Council in the coming weeks. 
• Last week, Sustainability and Economic Development staff hosted the Electric Vehicle Adoption for Businesses event. The event included presentations from Sustainability, Utah Clean Cities, and Leaders for Clean Air to help businesses plan for switching to electric vehicles and installing charging infrastructure for their fleets, customers, and employees. Participants also had the opportunity to engage in roundtable discussions to share their perspectives and experiences on this topic. The input received during this event helped City staff better understand the challenges specific to the business community and will be used to develop future City programs to advance electrified transportation charging stations to businesses.  

BUILDINGS

• This year, at the urging of Mayor Mendenhall, the Sustainability Department expanded the City’s Comprehensive Sustainability Policy to include all-electric provisions. This means that all new construction and major renovations of occupied City buildings more than 10,000 square feet will be evaluated for and, when practicable, designed and constructed to use all-electric technologies. 
• Similarly, Salt Lake City recently created financial incentives through our Redevelopment Agency for developers to build all electric buildings, eliminating the pollution from fossil fuel combustion in buildings 

SMALL EQUIPMENT EXCHANGES 

• The City is continuing a partnership with Utah Department of Environmental Quality to offer a gas-powered lawnmower exchange. In 2021, a total of 582 residents participated and Salt Lake City exchanged 509 gas powered mowers for electric options, which is the equivalent of removing 4.02 tons of pollution from the airshed annually. This year Salt Lake City residents exchanged a total of 539 gas powered mowers, contributing to a total of 8.28 tons of air pollution removed annually. 
• The Fiscal Year 2023 budget includes funding to transition Public Lands away from gas-powered riding lawnmowers to all-electric versions, as well as other equipment exchanges. 

RENEWABLE ENERGY 

• And we’re working hard to achieve net-100% renewable electricity for our entire community by 2030.

Let’s all work together this inversion season to keep the air clear!