Posted: No Idling!

The author of today’s post, Sheryl Canter, is an Online Writer and Editorial Manager at Environmental Defense.

Forward-looking New Jersey has done it again with its "Stop the Soot" initiative – an outreach program to educate people about the impact of idling car and truck engines. Idling spews pollutants into the atmosphere and burns a surprising amount of fuel. As noted on our driving tips page, idling for more than 10 seconds uses more gas and creates more global warming pollution than simply restarting your engine.

The New Jersey initiative has teeth: revised idling regulations went into effect on July 25. Diesel-powered vehicles may no longer idle for more than three minutes unless it’s very cold out, or they are picking up or discharging passengers – and even then they can idle for no longer than 15 minutes. There are a few exceptions – notably truckers using sleeper berths. They will be able to idle to power heating and cooling systems until May 1, 2010, but after that alternate power sources must be used.

I hope New Jersey’s initiative starts a movement across the country. No more idling – pass it on!

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  1. eschneider
    Posted August 29, 2007 at 7:45 am | Permalink

    I’m stunned. To state that idling for more than 10 seconds uses more gas / creates more emissions than restarting is absolutely false!

    When an automobile is started the computer is pre-programmed to enrichen the fuel mixture. On most fuel-injection systems, this condition lasts for about 8 seconds. After that, the computer transistions from “open loop” mode (pre-programmed settings, relatively inefficient) to “closed loop” mode (computer adjusts fuel mixture and timing according to input from engine sensors) This transition isn’t instantaneous, even on a warm vehicle.

    When an engine is at steady state condition (single speed, constant load), the combustion process can be at optimum combustion efficiency. The ONLY time a car is at steady state is at idle. Idling is when a car pollutes the least.

    So lets compare idling for 10 seconds vs. shutting the car down for 10 seconds and restarting.

    Idling for 10 seconds – engine runs at ideal combustion efficiency, with no load, no variations in engine speed, and at the lowest speed at which an engine operates.

    Starting after 10 seconds:
    – fuel mixture is enrichened for a default period (at least a few seconds)
    – the idle speed is increased for a period of time by the computer
    – the engine has to transition from closed loop to open loop mode

    Technical corrections aside — why, if we are going to create new laws to reduce emissions, are we targeting the least polluting condition of the already highest-regulated and enforced source of pollution – the automobile? Doesn’t it make more sense to spend our time and money enabling the enforcement of industrial pollution regulations?

    I compliment New Jersey for taking action. However, this measure is going to offer miniscule results. We can do much, much better by holding industrial and governmental polluters accountable, rather than letting those institutions buy and regulate forgiveness with lobbying and beaurocracy.

    To be clear – I would not propose reducing the regulation of automobile emissions. I am merely suggesting that the industrial and governmental sources of pollution be held to the same standards.

    With respect,

  2. Posted August 29, 2007 at 4:34 pm | Permalink

    Hi Eric,

    You’re describing just one type of vehicle – fuel-injected, gasoline-powered cars. The New Jersey law (and others like it) covers much more than that - old and new cars, and most notably diesel trucks and buses. That said, the 10-second rule for cars has been proven empirically. Here are some links:

    Canadian Office of Energy Efficiency – Idle-Free Zone – originally published the 10-second rule.

    American Society of Mechanical Engineers  – study of fuel use when idling versus restarting. Results show that restarting uses the same amount of fuel as idling with the air conditioner on for 6 seconds.

    Diesel engines can use more fuel idling than they do moving – as much as four times more (see this study on school buses in Los Angeles, and also this recent EPA study with similar findings). Studies have shown that soot from diesel engines can cause a whole host of health problems – asthma attacks, impaired lung function, heart problems, and even death. 

    Idling is a significant problem in large cities like New York and Los Angeles where people are often stuck in traffic. A car in gridlock emits up to three times the pollution compared to one in free-flowing driving conditions. You can learn about Environmental Defense’s work in New York on reducing traffic congestion at

    We’re also working with the mayor of New York on tougher enforcement of the existing idling law, which has been in effect for five years. Plus we are working on a no-idling policy for school buses in Texas, and Truck Stop Electrification (TSE) expansion so truckers won’t need to idle overnight while sleeping. Our GreenFleet initiative helps fleet owners reduce emissions.

    Many people idle their car engine in winter because they think it needs time to warm up. Not true! Today’s fuel-injected engines don’t need a warm-up period, and idling for long periods can lead to excessive engine wear.

    Avoiding pollution and engine wear are not the only benefits to not idling. You also can save gas and money. Here are some studies that demonstrate it: – "…you can drastically improve your gas mileage."

    Homemade Hybrids – "I kicked the idling habit and saved a gallon of gas per tank."

    With this Cost of Idling worksheet [PDF] from Argonne National Laboratories, you can calculate the savings for your own vehicle. For more tips on clean driving, visit Car Talk’s "Driving Tips for Tree-huggers".

    Not idling is good for the environment, good for your wallet, good for engines, and good for health. Everyone wins by simply shutting off an idling engine.

    Mel Peffers
    Air Quality Project Manager
    Environmental Defense

  3. eschneider
    Posted August 30, 2007 at 7:38 am | Permalink

    Hi Mel;

    Thankyou for the response. Discussions on these issues can only educate everyone (including myself).

    I did follow the links you posted, and they made some very good and valid points (and some unrelated very irresponsible claims) The Canada link made the point that allowing an engine to warm up for extended periods at idle is a very good one. I wholeheartedly agree that we should educate everyone that it would be more responsible to “hop in the car and go” rather than waiting for the heater to warm the car for 30 minutes when it’s cold outside.

    I also agree that traffic congestion is a huge contributor to automobile emissions output; however the effects of accelerating and decelerating on emissions are far greater than the idling problem. We need to figure out how to curb the influences of developers and law enforcement entities so we can get rid of those stoplights on major traffic arteries.

    However, I fear that I did not communicate my primary point well enough. Automobile emission regulations have come a long way, and continue to decrease with progressive reductions in noxious gasses. By comparison, the industrial sector has not made comparable progress, and in fact was DE-regulated by the current administration. Further, government entities – federal, state, and local – are mostly EXEMPT from regulation (police cars and school busses don’t have to pass emissions tests in New Jersey!!!!)

    here’s my point: if we are going to commit resources beyond existing regulations to reduce emissions, it is far more effective to address the largest contributor to the problem. As an air quality specialist, I’m certain you can agree that cars idling for 10-second intervals is not the biggest target on the dart board.

    It’s probably the easiest target, though.

    We can do better.


  4. Posted August 31, 2007 at 1:55 pm | Permalink

    Hi Eric,

    Thanks for the dialog on this. I agree that we all can be doing much more than not idling to reduce air pollution. We have many folks here at Environmental Defense working on several approaches including innovative transportation options and targeting reductions in the dirtiest sectors, not just cars. And we do target reductions of the the largest contributing sectors. We are actively trying to work with constraints like jurisdictional issues and technological limitations to find the best solutions in the real world. It is all about “finding the ways that work”.

    Luckily anti-idling is a simple thing to do to reduce emissions and it cost nothing – no new technology is needed to simply turn an engine off. Enforcement of anti-idling laws is often not as rigorous as it could be and any cost associated with enforcement can be offset with the penalty fine. Some may call it a low-hanging-fruit item on the clean air agenda but it does help. I appreciate your interest in the discussion. We can do more and we are working towards more reductions.

    All the best,
    Mel Peffers

  5. KingdomofOz
    Posted August 31, 2007 at 8:58 pm | Permalink

    Just today, I was looking out of the office tower I work in and observed the massive backup of traffic on our downtown interstate link. Everyday the same old jam up. Thousands of autos all moving at idle speed.

    Although there is constant highway construction in an attempt to curb the congestion, it is alarming that we ignore the real problem. Too many cars period. To that end it is popular to say mass transit is a complete failure in America. But the answer to this problem has already been proposed.

    First a little background on the subject. Public transit is in fact a failure in every city that still has passable roads. But the reasoning behind madness may be a surprise. Our rail systems, even with agressive expansion, could not dent the demand for transport. They are difficult to manage and people use them as a last resort.

    Buses are the obvious choice for virtually every city that wishes to place a band-aid on the situation and immediately sweep it under the rug. which leaves us with what other options?

    Well in the 70s, many companies small and large with some being rather well known, proposed PRT programs. PRT (Personal Rapid Transit) now carries a black eye for many reasons, most of which were and still are political.

    As the age of computers approached and everyone wanted to marry them to machines, the unproven technology proved to be not just a hard sell to voters who would have to pay for the them, but a political football that could easily be put to the side while retaining bragging rights for those who claimed to be addressing the transit problem.

    So here is solution: PRT Here is what it can do for any city, county or state. It can replace the auto. Sounds impossible right? Well don’t rush to judgement just yet. Lets push forward to the present day and note what proven technologies are available for such an undertaking.

    Ever wonder how all those products get to the grocery store shelves? Well maybe you haven’t, but the process is not very different from your daily commute to work. Tangible items must be moved from point A to point B. A large part of the process is a conveyor ride through a city sized warehouse.

    Computers and sensors control the whole shooting match. In short, if we want to replace the car, especially for people in the cities whom battle large traffic jams, we can do it.

    I personally have a PRT design that is environment friendly and efficient. It has been difficult to get governement types interested in this concept, mostly because they would rather leave infrastructure costs to somone else.

    Regardless of current reactions to PRT, it will become the answer to the car. Magically, one day a government official will back a PRT initiative thinking he has discovered the path to re-election, and the obvious will finally become reality.

  6. Posted May 23, 2010 at 9:52 am | Permalink

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