Clean Air – Nitrogen Oxide Emissions Reductions

Nitrogen oxides (NOx) are a group of gases that usually come from high-temperature fuel burning processes like those in cars, trucks and other vehicles; power plants; cement kilns; oil and gas activities; and off-road equipment. Nitrogen dioxide (NO2) is the gas of greatest concern because it can damage the environment and cause harmful health effects. While some nitrogen dioxide comes from natural sources, such as lightning, wildfires, and microbial activity in soils, human actions are the primary source of nitrogen oxides.

Why is this important?

High levels of NO2 can cause respiratory problems, harm plants, decrease visibility and increase acid deposition. NO2 adds to small particle pollution, which can reduce lung function and cause or worsen respiratory problems while increasing long-term risk for lung cancer and other lung diseases. NOx emissions are a large source of smog and can form harmful ground-level ozone. Ground-level ozone is a major public health issue in Colorado, especially along the Front Range, in some Western Slope communities and in the Four Corners area. It has been connected to decreases in lung function, inflammation of the airways, and increased respiratory symptoms. It can worsen lung diseases such as asthma and emphysema, and is linked to increased use of medication, hospital admissions and emergency room visits. NOx pollution also harms Colorado’s environment, including trees and forest ecosystems through acid rain and other types of deposition.   

Who is most at risk? Active children are at greater risk from ground-level ozone because their respiratory systems are still developing and they often spend time playing outdoors. Individuals with lung diseases such as asthma, emphysema and chronic obstructive pulmonary disease (COPD) are more at risk because their respiratory systems already are weakened. Active adults who work outside (i.e. construction workers) or exercise outside (i.e. runners, bikers) are at higher risk.

What is being done?

CDPHE regulates and makes plans to reduce NOx emissions in Colorado. NOx reductions are a key part of ground-level ozone reduction efforts, Colorado’s Regional Haze State Implementation Plan and the 2010 Colorado Clean Air-Clean Jobs Act. As part of the Regional Haze and Clean Air Clean Jobs, 16 older, coal-fired power plants and cement kilns will close, convert to using cleaner-burning natural gas, or add additional emission control equipment in the coming years. A major ozone reduction effort is the Colorado Automobile Inspection and Readjustment (AIR) Program (the vehicle emission testing program), which reduces pollution from the dirtiest

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vehicles in Denver and the North Front Range area by limiting the amount of NOx that vehicles are allowed to release. Since 1995, the program has required cars to meet clearer standards several times. Federal on/off road vehicle standards are also being phased in through 2025. In addition to these efforts, Colorado regulates engines that are used in oil and gas exploration and production activities and enforces Clean Air Act emissions standards for NOx that target things like engines, motor vehicles, small equipment to power plant boilers and diesel generators. NOx emissions controls are very effective and widely used in cars and power plants. In fact, NOx levels have decreased by about 50% in the Northern Front Range since the 1980s.

Where do we want to be?

Statewide, NOx emissions are expected to decrease about 30% from 2011 - 2023. The following graph shows where most NOx emissions were coming from in 2006-2013. Other than the recent increases in the Oil and Gas (O&G) category, NOx emissions by category have either decreased or stayed flat over the past 19 years. Because ozone levels are high in Denver and the North Front Range area, CDPHE may look into additional NOx emission controls in the future to further reduce ozone. With current controls, overall NOx emissions in the Denver area are expected to decrease 27% from 2011 – 2017.

What can you do?

To Protect yourself:  Sign up to get air quality health advisories through: https://www.colorado.gov/airquality/req uest_alerts.aspx  Before heading out, check the air quality in your area at AirNow: https://airnow.gov/  If air quality is bad, people who are more sensitive to air quality, like those with heart or lung disease, older adults, and children, should try not to do long or difficult work outside. Everyone else should try to reduce long or difficult work outside.

To Protect our Air:  Keep your car well maintained and tires well inflated.  Try not to idle your car while waiting. Turn off your engine instead.  Refuel in the evening.  Skip unnecessary car trips or combine them to minimize the number of trips you take.  Take the bus, carpool, walk or ride your bike to work or school at least once a week.  Delay mowing until evening (after 5 p.m.)  Maintain your gas-powered mower or switch to new earth friendly lawn equipment.  Xeriscape to reduce lawn area and reduce the need for watering and mowing.

Colorado’s 10 Winnable Battles Clean Air Clean Water Infectious Disease Prevention Mental Health and Substance Abuse Obesity Oral Health Safe Food

Injury Prevention Tobacco Unintended Pregnancy