State of Illinois
Pat Quinn, Governor
Illinois Environmental Protection Agency
Douglas P. Scott, Director
Illinois Environmental Protection Agency Fact Sheet
“Ladies and Gentlemen: Turn Off Your Engines!”
What You Should Know About Diesel Truck Idling
FACT: More states and local governments are passing laws or ordinances to limit
idling and to get truck and bus drivers to turn off the engine.
Idling has become a major issue with the public, due to the nuisances, public health,
and environmental concerns related to parked diesel trucks or buses whose engines
are unnecessarily left running. This is especially prevalent at truck stops, at loading
docks where product pickup and delivery takes place, and at schools where a large
number of trucks or buses are often left idling. The goal of the laws and ordinances
is to restrict occurrences of “unnecessary idling” where the engines of parked trucks
or buses are left running without any need or purpose.
The State of Illinois passed an idling law (625 ILCS 5/11-
1429) effective July 2006 for the air quality nonattainment
areas of the state, specifically the Metropolitan Chicago and
East St. Louis regions.
The law prohibits a truck or bus from idling for more than ten
minutes during any sixty minute period. There are several exceptions to the law,
addressing operational needs for when the engine needs to run for a specific
purpose. Several municipalities are considering adopting ordinances to address
truck idling and to complement the State law as needed. The intent of the law is to
ensure that a truck or bus driver shuts the engine off when it is unnecessary for the
engine to be left idling.
FACT: Idling is detrimental to the driver and to the public.
For drivers that sleep in their cabs, the noise of the diesel engine often keeps them
awake, resulting in poor rest. In addition, driver exposure to the diesel emissions
that enter the truck cab is not only a nuisance but it also aggravates existing
respiratory problems, increases the risk of future respiratory ailments, and may lead
to other types of adverse health conditions. Since an idling truck does not move, the
diesel fumes and associated pollutants, including several types of air toxics, build up
in and around the truck creating a “cloud” of emissions. If several trucks are parked
in the area, this “cloud” can linger and build up to very unhealthy levels, impacting
people living in nearby residential areas or visiting nearby businesses. It is not
uncommon for exposure to diesel emissions to be higher inside the cab than outside
of it. Nationally, the idling of trucks collectively accounts for 11 million tons of
carbon dioxide (a greenhouse gas), 200,000 tons of nitrogen oxides (a “smog” or
ground-level ozone forming pollutant), and 5,000 tons of particulate matter (the
“sooty emissions” coming off the stack) being emitted into the air each year.
FACT: Idling causes increased maintenance costs and engine wear.
An idling engine operates below its optimum temperature, and due to this lower
temperature, fuel is not fully burned during the combustion process. The unburned
residues contaminate the oil and form deposits within the engine, which can
decrease fuel economy up to five percent as well as reduce engine life. In addition,
lower engine temperatures resulting from idling allow water to condense within the
exhaust pipes and mufflers, leading to premature corrosion. The trucking industry
has analyzed the impact of idling on diesel engines, both in terms of maintenance
and engine wear costs. Long-duration idling creates the need for more oil and oil
filter changes and accelerates the timeframe for scheduled maintenance. Similarly,
the longer the idling time and the more frequent the idling, the sooner the engine
will need to be rebuilt or replaced.
FACT: A diesel engine will restart after it is turned off.
In the past, drivers were instructed to NOT turn off a diesel engine out of concern
that the engine would not readily restart. Contrary to these types of idling practices
once utilized in the industry with much older engines, diesel engine manufacturers
insist that engines will restart after being turned off, and that starter technology has
improved so the increased frequency of restarts will not harm the truck’s ignition.
This is true of diesel engines of all types and sizes, including the larger engines used
in over-the-road trucks. Many drivers still use outdated idling practices prevalent
for much older diesel engines and starters when leaving the vehicle unattended, and
this practice has long been outdated. Exceptions are noted when the weather is
extremely cold and engine block freezing or fuel gelling are a concern, but under
typical conditions, diesel engines can be turned off when the driver leaves the truck
unattended and readily restarted upon his or her return.
For more information, please contact:
Illinois Environmental Protection Agency
Division of Mobile Source Programs
1021 North Grand Avenue East
Springfield, Illinois 62794-9276
217/557-1441
www.epa.state.il.us
Printed by authority of
the State of Illinois
Revised Aug 2008 36015 500 copies
