Air Quality DivisionOklahoma Department of Environmental Quality

An idling vehicle is one whose engine is running when it is parked or not in use. Common reasons for engine idling are:◦ warming up the vehicle◦ waiting for someone◦ doing an errand◦ personal comfort◦ Listening to the radio

These examples are NOT considered idling:◦ regular stopping in traffic◦ stopping at loading/unloading zones...

Air PollutionIdling school buses and refuse trucks can pollute air in and around the vehicle. Exhaust from heavy-duty diesel engines can also enter buildings through air intakes, doors, and open windows. Diesel exhaust from buses and refuse trucks created by excessive idling can be a health concern.

Wasted Fuel and MoneyIdling buses and refuse trucks waste fuel and money. When idling, a typical school bus engine burns approximately half a gallon of fuel per hour. School bus fleets and refuse truck fleets that eliminate unnecessary idling can save a significant amount of money in fuel costs each year.

Example of how much money can be saved:

◦ Fleet Size = 50 buses or 50 refuse trucks◦ Reduced Idling Time = 60 minutes per day

Saves you a total of:◦ 4,500 gallons of diesel fuel per year◦ $18,000 per year

Engine Wear-and-TearSchool bus engines and refuse truck engines do not need to idle more than a few minutes to warm up. In fact extended idling causes engine damage. Engine manufacturers generally recommend no more than three to five minutes of idling.

Diesel exhaust contains significant levels of small particles, known as fine particulate matter

Fine particles pose a significant health risk because they can pass through the nose and throat and lodge themselves in the lungs

These fine particles can cause lung damage and aggravate conditions such as asthma and bronchitis

According to the EPA, particulate matter, especially fine particles, is responsible for thousands of premature deaths across the U.S. every year

EPA has determined that diesel exhaust is a likely human carcinogen

People with existing heart or lung disease, asthma or other respiratory problems are most sensitive to the health effects of fine particles

Children are more susceptible to air pollution than healthy adults because their respiratory systems are still developing and they have a faster breathing rate

The elderly

Myth: It's important to warm up the engine with a long idle period, especially in cold weather. ◦ Fact: With today's diesel engines, bus and engine

manufacturers routinely suggest a warm up time of less than five minutes. In fact, running an engine at low speed (idling) causes significantly more wear on internal parts compared to driving at regular speeds.

Myth: It's better for an engine to run at low speed (idling) than to run at regular speeds. ◦ Fact: Running an engine at low speed causes twice the

wear on internal parts compared to driving at regular speeds. 

Myth: The engine must be kept running in order to operate the school bus safety equipment (flashing lights, stop sign). ◦ Fact: Safety equipment can be operated without the engine

running through re-wired circuitry for up to an hour with no ill-effects on the electrical system of the bus.

Myth: Idling is necessary to keep the cabin comfortable. ◦ Fact: Depending on the weather, many buses and trucks will

maintain a comfortable interior temperature for a while without idling. Idling is not an efficient way to keep the cabin warm. Routes should be timed so occupants do not need to spend a lot of extra time on the bus when it is not en route. In addition, auxiliary heaters can be purchased.

Myth: It’s better to just leave the engine idling because a "cold start" produces more pollution.◦ Fact: A recent EPA study found that the emission pulse

measured after the school bus is restarted contains less carbon monoxide, nitrogen oxides, and other pollutants than if the school bus idled continuously over a 10-minute period. The analysis indicated that continuous idling for more than three minutes emitted more fine particle (soot) emissions than at restart.

Reduce early morning idling time to limit exhaust build up in buses and refuse trucks

Designate an indoor area for drivers to wait if they arrive early

Position buses and refuse trucks away from building air intake vents so pollution does not accumulate inside the building

Change vehicle circuit configuration to run the lights and heating/cooling off the battery

Limit caravanning-position buses and refuse trucks so tailpipes do not blow directly towards another bus/truck

No Yes

Encourage children to sit near front of bus when not full

An Idling reduction policy is a required component of the application and award

In the applications, applicants will need to describe the idling reduction policy to be implemented

Include how all unnecessary idling will be eliminated by your organization such that idling time is minimized in all aspects of fleet operation

An Idling reduction policy is a required component of the application and award

Include current annual idling times and current annual fuel usage and anticipated annual idling times and anticipated annual fuel usage after policy implementation

Include time limits, exceptions and anticipated training

If a current policy is in place, please thoroughly describe the policy