Air quality

Finding solutions to improve air quality

Find out how our clean and efficient power systems reduce energy emissions every year

Clearing the air with our idle reduction program

See how our idle reduction program has reduced the equivalent of 617 car trips across the state annually


Due to its unique topography and quickly growing population, Utah experiences a number of challenges in maintaining healthy air quality for its citizens, particularly in the more densely populated areas along the Wasatch Front. Rio Tinto Kennecott is aware of these issues and the impacts we have on air quality, and we are working hard to reduce harmful impacts on Utah’s air quality.

We have an ongoing commitment to build sustainable development into all of our business decisions, and we are focused on helping maintain clean air quality for Utah.

Kennecott’s emissions contribution

Technical analysis conducted by the Utah Division of Air Quality (UDAQ) indicates that Kennecott’s annual emissions are a minor contributor to total annual emissions in the Salt Lake air shed, as compared to area sources — such as urban activities, home heating, small businesses, solvent use and graphics; and mobile sources — such as cars, trucks and other mobile equipment.

More specifically, based upon the most recent UDAQ data, Kennecott’s total annual emissions of PM2.5 particles and PM2.5 precursors represent approximately 5.8 percent of total annual PM2.5 and precursor emissions in the Salt Lake air shed. This compares with 57.4 percent from area sources and 29 percent from mobile sources.

See how particulate matter forms here.

(The Salt Lake air shed is currently in a non-attainment status regarding the U.S. EPA’s NAAQS for PM2.5. In this regard, PM2.5 particulates and PM2.5 precursors are the primary emissions of concern that affect Salt Lake City’s winter inversion episodes that are the cause of Salt Lake’s non-attainment status).

PM2.5 = particulates that are smaller than 2.5 micometers in diameter.

PM2.5 precursors = emissions that are not particles originally but which can turn into particles when they react in the atmosphere. Pollutants that can react to form PM2.5 are SO2, NOX, and VOCs

This information is further summarized in the graph below:

Moreover, the contribution of Kennecott’s emissions during winter inversion episodes (the periodic winter-time meteorological events that cause the Salt Lake air shed to not attain USEPA NAAQS for PM2.5) is significantly less than this annual 5.8 percent because:

• 43.9 percent of Kennecott’s annual PM2.5 and precursor emissions are generated from Kennecott’s power plant. The power plant does not operate during the winter months – so does not contribute any emissions during wintertime inversion events.

• 46.2 percent of Kennecott’s annual PM2.5 and precursor emissions are generated from Kennecott’s mining operations (generally tailpipe emissions from Kennecott’s fleet of haul trucks and associated equipment). The geographical position and elevation of the Bingham Canyon Mine is such that emissions during wintertime inversion events are effectively trapped within the mine by the same meteorological conditions that trap emissions within the Salt Lake Valley — meaning they also do not contribute to the elevated PM2.5 levels that are experienced within the Salt Lake Valley during winter inversion events.

The majority of Kennecott’s PM2.5 precursor emissions are NOx (or oxides of nitrogen). These are less impactful than PM2.5 precursor constituents more commonly emitted by transportation and urban sources.

UDAQ's most recent technical analysis indicates that of all sources present in the Salt Lake Valley, small sources of volatile organic compounds (VOCs) (such as paint shops, dry cleaners, auto body shops and cars) have the most impact on formation of pollution during an inversion. Using the model, UDAQ has demonstrated that a decrease in VOC emissions from those sources would result in the largest decrease in pollution during an inversion, compared to decreases of other emission types (such as NOx).

These factors are supported by independent air monitors operated by the State of Utah, which consistently demonstrate that the ambient air surrounding Kennecott’s operations has the best quality (lowest monitored impacts) in the Salt Lake Valley, and that the ambient air surrounding Kennecott is significantly below the national ambient air quality standards.

Kennecott’s role in reducing emissions

At Kennecott, we are proud of the role we have played and continue to play in reducing our emissions. We are also proud to work with other air quality improvement champions in the community to support the reduction of emissions within the Salt Lake air shed.

Some key specific examples include:

• Combined heat & power plants: Kennecott has installed a 6.2 MW Combined Heat and Power (CHP) system at the Kennecott refinery and a second system is being installed at our Molybdenum Autoclave Process (MAP) facility currently under construction. CHP systems reduce air emissions by more than 90 percent compared to traditional steam and electric systems.

• Smelter cogeneration: Kennecott’s smelter captures and converts the waste heat from the flash smelting and converting furnaces at the acid plant to generate about two-thirds of its electrical demands.

• Smelter emissions capture: Kennecott’s smelter captures 99.9 percent of all sulfur emissions and is considered one of the cleanest in the world.

• Power plant upgrade: Kennecott plans to convert three existing boilers at our onsite power plant to combined cycle natural gas, resulting in a reduction of 3,400 tons per year in emissions of PM2.5 and precursors.

This change will double the amount of power while reducing emissions by more than half at the plant.

Read more about how our improved power-generation strategy helps improve air quality in the Salt Lake Valley.

• Upgraded truck fleet: Larger payload capacity and higher efficiency engines result in a reduction in tailpipe emissions. Learn how our haul trucks are made and how they support our commitment to sustainable development by watching the video.

• LEED-certified buildings: Kennecott’s portfolio contains five high-performing LEED-certified buildings with several more awaiting certification. The Rio Tinto Regional Center was the first LEED Platinum-rated building in Utah.

• Daybreak community: Every new home in Daybreak is energy-star rated and comes with a Home Energy Rating System (HERS), which provides an index rating of each home’s energy efficiency. Kennecott played a pivotal role in the development of the TRAX Mid-Jordan light rail line, which connects Daybreak with the north-south main line.

• Idling program: Kennecott has implemented two vehicle idling reduction programs: one for light/medium duty vehicles throughout the operation and one for haul trucks at the mine. The idling programs have resulted in a reduction in tailpipe emissions. Read more...

• CNG vehicle program: Kennecott has implemented a CNG vehicle pilot program resulting in a reduction in tailpipe emissions.

• Renewable energy research: Kennecott has installed more than 40 kWs of solar and wind generation at seven individual project sites.