Sources of Emissions

Did you know that vehicles are the primary source of precursor emissions for PM2.5 pollutants? They account for almost half of the typical winter workday emissions, with area sources (homes, small businesses, buildings, etc.) close behind contributing 39 percent and industry point sources contributing 13 percent.

Sources of PM2.5

Because the DAQ has been actively working to reduce larger particulates (PM10) in the state in recent years, it has already implemented a number of emissions control strategies. These strategies have resulted in significant particulate reductions. Historically, the primary reduction strategies have been directed at industrial emissions. But with PM2.5, industry currently contributes to only approximately eleven percent of the pollution. This leaves reductions in mobile and area sources as the critical focus areas for reducing the emissions that form PM2.5. Here is a description of the non-industrial sources:

  • Mobile sources – On-road vehicles
  • Area sources – Small industrial and commercial sources that emit less than 100 tons per year of pollution and sources generally associated with urban living, including gas and wood stoves, dry cleaning facilities, gas stations and water treatment facilities.

Summer Ozone

Summer time ozone is pollution created by a mix of emissions combined with high temperatures and bright sunshine. Even though it’s harder to see than winter inversion, summer zone issues do exist and can cause harmful risks to those who are very young, elderly and have pre-existing health problems. In order to determine whether Utah’s pollution levels are above or below the current ozone standard (.75 parts per million), the Division of Air Quality uses 15 monitors to record ozone pollution levels in real time. The hotter the weather, the higher the pollution level spikes. The good news is that summer ozone has a daily cycle of lower pollution levels with lower temperatures in the morning and evening. This means that Utahns can still enjoy summer by staying inside during the afternoon and enjoying the cooler parts of the day without exposure to high ozone.


While it might not seem like hair spray, carpet cleaner or air fresheners could contribute to Utah’s PM2.5 problem, they do. Solvents contained in common products such as paints, varnishes, preservatives, waxes, dry cleaning products, polishes, degreasers, and automotive products emit VOCs, which contribute to the formation of fine particulates. New carpeting, backing and adhesives; wood products manufactured using certain glues; finishes and vinyl type flooring and wall coverings can also release VOCs into the air.For consumers looking for a way to make more air-friendly purchases, the EPA’s Design for the Environment (DfE) program screens and identifies products through a stringent scientific review process. Chemical-based products carrying the DfE logo meet strict EPA standards. The DfE Standard for Safer Products incorporates the California Air Resource Board’s VOC regulations, which limit the amount of VOCs that can be used in various cleaning product categories. The EPA has a list of DfE labeled products on its website.


How to Idle Less
While there are some circumstances where idling is unavoidable, there are a lot of ways drivers can idle less. If the line at the drive-through restaurant or bank is slow, consider turning off your vehicle while you wait. You can also park and go into the building. When waiting for passengers, consider the weather. If the temperature is moderate, it is a good idea to turn off the engine. This is especially important while waiting to pick up school children since a child’s lungs are more susceptible to damage an adult’s. Unnecessary idling around schools can exacerbate childhood asthma and other respiratory ailments.The best technology to reduce idling is driving a hybrid vehicle. A hybrid shuts off the engine when stationary so there are no emissions from the tailpipe while waiting in traffic or a drive-through. As hybrid vehicles gain a larger market share, it is likely that fewer vehicles on the road will idle unnecessarily.Idling problems extend beyond consumer vehicles. Reducing idling in community vehicles, such as police cruisers, school buses, taxis, ambulances and government fleets, can bring even larger benefits. While emergency vehicles (ambulances, police cars, and fire engines) are usually exempt from anti-idling regulations, there is equipment that can be added to these vehicles to prevent idling while providing power and comfort. Ambulances can plug in at hospitals to keep equipment running, police vehicles can use automatic start-stop devices or supplementary power sources and school buses can use block heaters to warm the engines to
operating temperatures in the morning.Here are some simple things you can do to reduce idling courtesy of Idle Free Utah, California Energy Center, Natural Resources Canada and the U.S. Department of Energy Vehicle Technologies Program:

  • If you are going to stop your car for more than 30 seconds, turn off the engine. When you start your engine, do not step down on the accelerator, simply turn the key to start.
  • Rather than using a drive-through window, park your car, walk inside, do your business and then return to your car.
  • Warm your car in the winter by driving rather than idling.
  • In colder areas, use an engine block heater to warm the engine. This improves fuel efficiency and reduces emissions.
  • Use remote starters wisely. Don’t turn your vehicle on before you are ready to leave.
  • Track your emissions reductions using the TravelWise Tracker.
  • Talk to the principal of your child’s school about posting anti-idling signs in areas that school buses and parents wait for pick-up and drop-off.
  • Work with your school board on a district-wide anti-idling campaign.
  • Talk to the manager of your bank, drive-through restaurant or pharmacy about ways to reduce wait times in drive-through lines. Suggest that signs be posted to remind patrons not to idle while waiting.
  • Encourage your employer to implement anti-idling policies at the workplace.

Idling Facts
Research indicates that the average person idles their car five to ten minutes a day. Cutting idle time makes sense during inversions, because reduced idling also reduces the emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs), both precursor gases for the formation of PM2.5 during inversions.

Idling also increases fuel costs. Ten seconds of idling can use more fuel than turning off the engine and restarting it. A car idling for two minutes uses about the same amount of fuel it takes to drive one mile.

Idling your vehicle also increases our nation’s dependence on petroleum, reduces the fuel economy of your vehicle, costs you money, emits pollutants, and wastes natural resources. Researchers estimate that idling from heavy-duty and light-duty vehicles wastes about 6 billion gallons of fuel annually.

UCAIR’s Idle-Free Program provides information about idling, including health impacts, calculators that can help you see how much money you could save by idling less and a list of partners and resources.

Modern Vehicles Don’t Need to Idle
Advances in vehicle technology have eliminated much of the need for idling. Computerized controls in today’s vehicles bring the engine up to operating temperatures more quickly when the vehicle is moving than when it is idling.

The catalytic converter that reduces emissions also operates much sooner if the car is driven right away rather than idled. Even on the coldest day, it takes a modern vehicle almost twice as long (about 10 minutes) to warm the engine when the car is idling than when it is moving.

In moderate weather, the catalytic converter can even maintain its operating temperature and immediately resume emissions reduction if the driver restarts the car for up to 30 minutes after he or she turns off the ignition. Similarly, today’s gasoline and diesel vehicles alike do not suffer damage from turning the key on and off. Starters and batteries are much more durable than people believed they were in the past. In fact, today’s owner’s manuals, which usually contain information on how to get the best and most economical fuel and engine performance, generally do not recommend idling.

Myths About Idling
Take the quiz below to test your knowledge about idling.

Idling is good for your engine.
FALSE: Excessive idling can actually damage your engine components, including cylinders, spark plugs, and exhaust systems. Most car manufacturers believe that idling more than 30 seconds is not only unnecessary, but actually unadvisable.

Idling wastes fuel, costs money, and harms air quality.
TRUE: Idling wastes an enormous amount of money because it burns fuel that isn’t used to drive the vehicle. A car that is idling gets zero mpg. Idling also harms air quality by producing exhaust emissions that emit fine particulates into the air and increase the formation of ozone.

It is necessary to idle your car on cold winter days.
FALSE: Many components of the vehicle—including the wheel bearings, tires and suspension system—will warm up only when the vehicle is moving. You need to idle no more than 30 seconds to get the oil circulating through the engine.

It is a good practice to shut off the engine when your vehicle is stopped for more than:
A – 10 seconds
B – 10 minutes
C – 30 minutes

A – More than 10 seconds of idling can use more fuel than turning off the engine and restarting it. If you are stopped for more than 10 seconds, you’ll save fuel and money by turning off the vehicle and then restarting it when you’re ready to drive away.

I should turn my vehicle off when I am caught in stop-and-go traffic or at a long stoplight.
FALSE: The 10-second rule is a good one, but you can’t avoid all idling. Turning off your vehicle in these situations might disrupt traffic. It could also cause you to speed away after you restart the engine, which would offset any fuel savings and increase emissions.

Idling is a problem only in winter.
FALSE: While we tend to associate idling with warming up cars in the winter, idling is a problem year round. Motor vehicles emit numerous pollutants, including carbon monoxide, nitrogen dioxide, and volatile organic compounds. Some of these pollutants lead to the formation of ozone, which is a major problem in Utah during the summer months.

I need to idle my car on cold and hot days to stay comfortable.
FALSE: Idling on a warm day with the air conditioning on burns even more fuel than idling without the air conditioner. Opening a window in the summer or putting on warm clothes in the winter can reduce the need for idling. Alternative technologies to idling can provide comfortable conditions for drivers of heavy-duty vehicles.

Which of the following are common reasons for idling?
A – Warming up a vehicle.
B – Sitting in the drive-through lane of a fast-food restaurant.
C – Stopping to talk to a friend.
D – Waiting for someone.
E – All of the above.

E – All of these are common reasons for idling and all of them can be avoided.

Restarting my car many times, rather than letting it idle, is hard on the starter and other parts.
FALSE: Studies show that restarting the engine many times has little impact on components such as the battery and the starter motor. Component wear caused by restarting the engine is estimated to add $10 per year to the cost of driving, money that will likely be recovered several times over in fuel savings from idle reduction.