Polluter Scooters (and mowers)

July 26, 2008 | By | 16 Replies More

Several of my friends have recently purchased scooters. They are thrilled that they are now doing something good for the environment. They point to the 90 miles they will now get for each gallon of gasoline burned.

Despite the good gas mileage, not all scooters are good for the environment. Those thinking about purchasing a scooter should be aware that two-stroke engines contribute mightily to pollution. Not all scooters are two-stroke engines, but many of them are. The special Science, Technology and the Future issue of Discover magazine (Dated May, 2008, but not available online) indicates that throughout Asia, scooters with two-stroke engines are producing a vast amount of pollution.

How bad for the environment are two-stroke engine scooters?

Unlike the developed nations’ larger but much more efficient automobiles, which views four-stroke engines, two-stroke vehicles spew great volumes of dangerous hydrocarbons, carbon monoxide and smoke. A single two-stroke engine produces pollution equivalent to that of 30 to 50 four-stroke automobiles. With roughly 100 million motorcycles in Asia–roughly half of them using two-stroke engines–that translates into as much as 2.5 billion cars’ worth of smog.

Two-stroke engines produce a lot of pollution because the fuel-air mixture in them gets contaminated with the engines lubricating oils. Simultaneously the combustion chamber draws in the contaminated mixture as exhaust gases are expelled through an exhaust port. Some of the fuel and oil gets mixed up with the exhaust.

Two-stroke engines show up in many other contexts too, including many machines used for yard work. For instance, most gas burning lawnmowers using two-stroke engines.  How much pollution do gas-powered lawn mowers cause?  Boulder and County News has some shocking answers:

Traditional gas-powered lawn mowers are responsible for 5 percent of the nation’s air pollution, according to the Environmental Protection Agency, which recently created emission regulations for small engines like those that lawn mowers use. One gas mower running for an hour emits the same amount of pollutants as eight new cars driving 55 mph for the same amount of time, according to the Union of Concerned Scientists.

This is a good reason to consider using a push mower without a gasoline engine if you have a small to medium sized yard (here are more lawn mower stats from the EPA).  Today’s push mowers are much smaller and lighter than the push mowers used by your grandparents. It’s really a good option for a lot of reasons, including a reduction in both air pollution and noise pollution.


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Category: Environment

About the Author ()

Erich Vieth is an attorney focusing on consumer law litigation and appellate practice. He is also a working musician and a writer, having founded Dangerous Intersection in 2006. Erich lives in the Shaw Neighborhood of St. Louis, Missouri, where he lives half-time with his two extraordinary daughters.

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  1. Polluter Scooters (and mowers) | Dangerous Intersection | Sense Humor Blog | February 28, 2009
  1. Niklaus Pfirsig says:

    I used a cordless electric mower and I really liked it. But it wore out and was replaced by a less expensive gas burner, Now the gass burner is worn out and the creeping decrepitude of arthrits has me considering a robotic lawnmower. Looking at the available models, I noticed that there is one that with solar assisted charging.

    Actually most lawnmowers use four-stroke engines. The real offenders of the lawn care tools are the leaf blowers, chainsaws and gasoline powered weed- whackers which use traditional slotted port 2-stroke engines. The traditional two-stroke design requires lubricating oil to be added to the fuel.This is because the fuel is also used as a lubricant in the crankcase. The slotted port design coupled with the additional oil results in a high level of hydrocarbons in the exhaust.

    Some newer two-stroke designs use electronic fuel injection which isolates the fuel path from the crankcase, thus making it unnecessary to mix oil into the fuel, Also, since the fuel is metered in near the end of the compression stroke, the design is cleaner burning and more efficient than a carburetted four stroke engine. EFI 2-stroke engins are used in snowmobiles, outboard motors, and in many of the top of the line scooters.

  2. Erich Vieth says:


    Thanks for the correction regarding lawn mowers. I should have done my research better before assuming they were mostly two stroke engines. Nonetheless, they are horrific polluters, as are (as you point out) so many of those other yard toys.

    Check out these incredible statistics regarding gas-powered lawn mowers (from Wikipedia):

    The main issues with the gasoline mowers are air pollution and safety. A 2001 study showed that such a mower emits the same amount of pollution (emissions other than carbon dioxide) in one hour as driving a 1992 model car for 650 miles.[1] Another estimate puts the amount of pollution from a lawn mower at four times the amount from a car, per hour.[2] This is largely due to the lack of any emissions equipment on most lawn mowers; cars have had catalytic converters, fuel injection, and other emissions-control devices for decades, while most mowers have little more than a simple muffler and carburetor. Their single-cylinder engines also need to run with a richer fuel-air mixture because of the irregular flow through the carburetor, leading to incomplete combustion. This is true of all small gasoline engines; the United States Environmental Protection Agency reports, for example, that "recreational watercraft can emit as much as 348 cars".[3]

    In addition to air pollution, the EPA states that 17 million gallons of fuel, mostly gasoline, are spilled each year while refueling lawn equipment. That is more than all the oil spilled by the Exxon Valdez, in the Gulf of Alaska. Oil spills contaminate groundwater as well as evaporate into the air making smog-forming ozone when heated by sunlight.

    This amount of spilled fuel is ghastly. I had no idea. This is even more reason to buy a non-engine push more if you have a small to medium yard (or to convert your grass lawn to an alternative!).

    My wife and I both use our $100 push mower to cut our 1/5 acre yard. It really doesn't take any more effort that cutting the yard with a gas powered mower, because modern push mowers are so incredibly light and well-designed. Here's the company that made our lawn mower (which we bought at Home Depot): American Lawn Mower Company. https://www.reelin.com/ At the American website, the company touts that you can fuel it's lawn mowers "for the price of a banana." https://www.reelin.com/Advantages.aspx

  3. Edgar Montrose says:

    I'm glad to see the correction about 4-stroke lawn mowers. The only mainstream 2-stroke lawn mowers in my memory were from the old Lawn Boy brand, which I haven't seen in quite some time.

    In addition, there is an almost complete abandonment of 2-stroke engines in all other applications. While there have been prototypes of "clean" 2-stroke street motorcycles, you won't find a single production model. Even off-road motorcycles are making the switch to 4-stroke engines. Ditto for snowmobiles, personal watercraft, marine outboard motors, even model airplanes. The only holdouts seem to be chain saws and leaf blowers. So, in general, this is a known problem and solutions are already being put into effect.

    Regarding pollution from lawn mowers, there is more to the story than just the emissions from an individual engine. A mower may emit more pollution than an auto, but the mower is typically used for about an hour a week, six months a year. An auto is probably driven more than an hour a day, year-round. I'm not saying that lawn mower pollution is not a problem; I'm saying that it's not as big a problem as the raw numbers imply.

    Finally, while I would love to be able to use a push mower, currently I mow almost an acre, once a week, with a walk-behind power mower. That alone is strenuous enough for me.

  4. Dan Klarmann says:

    Let's also consider the word "pollution". A hundred years ago, the internal combustion engine was hailed as the way to end pollution! No longer would one have to watch ones every step when crossing the street, nor would the air be filled with the dry dust produced by all the horse droppings that didn't make their way onto ones shoes.

    Always consider the qualitative difference between the particulate "pollution" produced by a small 2-stroke engine, a local problem that washes right out of the air, and the sulfates, nitrates, and carbon-dioxide massively produced by the million-fold more popular 4-stroke engines, that can take generations to reabsorb into the ecosystem, drifting around the world creating acid rain and probably accelerating global warming.

    Also consider the difference in the cost of the engines, a good measure of how much energy goes into producing and delivering them. A cheap 2-stroke starts quickly, runs for short periods, and then spends most of its time at rest (outside of the marine sphere).

    I use a plug-in electric mulching lawnmower that I salvaged from the trash and repaired. It cost no energy to produce, compared to buying a new one. And I kept it out of the landfill.

    Sure, it uses energy. I live above a big coal field, a nuclear plant is nearby, and wind credits are available from my utility. Big power plants convert fuel to useful energy much more efficiently than any small engine, whatever the design. Mowing my whole lawn uses as much energy as two minutes of central air conditioning (one zone). And I don't have central air.

    If this electric ever dies beyond my ability to repair it, I do have an old, salvaged push mower back in the depths of my garage. It'll need sharpening. I also have a vintage scythe, but I don't think the city will let me grow the grass long enough to be able to mow with it.

  5. Marlon says:


    Since you are a bike guy, you'll like this:


  6. Alison says:

    Lawns themselves, of course, are also wasteful. I know I'm preaching to the choir, although my neighbors would beg to differ. I'm surrounded by people whose automatic sprinkler systems keep their lawns drenched even during drought restrictions (and in the middle of rainstorms!) and who don't seem to worry about the chemicals they apply regularly getting into our water table or into the bay, even if they themselves have well water or fish the bay for food. The clippings go into the trashcans even though we have a huge town facility for processing yard waste, and we've been scolded by the neighbors for composting (one neighbor, even, whose dog waste smells worse and might even take up more space than our grass clippings.)

    Bit by bit, I'm terracing the yard with found rocks and stones, making beds of perennials and evergreens, and letting the moss take over. It probably doesn't make up for using our central air or driving a van, or using plastic bags or any number of other things, but even making a small compromise is better than none at all. That's probably what your friends are feeling about their scooter purchases. While they might have done something even better, at least they're showing a willingness to start making a change. Even if you have reason to criticize their possible misdirection, you might instead want to take that ball and run with it – use their feeling of satisfaction with this step as an opportunity to open up a dialogue about other things they could do.

    Most people make a lot of small steps, picking up information as they go, before they make any big changes. If you make them think, make them ask themselves questions, it's more likely that they'll be motivated to make informed choices than if you criticize a choice they've already made without considering how it might show a change in their direction. I'm sure you aren't getting in their faces and screaming, "You moron! You really think you're helping the environment with that @#@** thing?!?!?" but asking questions about how much gas they've actually saved, how many trips they've used it instead of the car, anything that gets them talking about the desired result of their purchase will start them thinking about what to do next.

  7. Erich Vieth says:

    Alison: I haven't criticized the new scooter buyers, although I did ask them both whether they had bought two stroke versus four stroke scooters. Neither of them knew. I wish that this information was made salient at the dealers, but it apparently isn't. Your main point is a good one: encourage all attempts to change for the better regarding the environment. After all, it's often that first, sometimes flawed, step that is the most difficult.

    Edgar: I appreciate that mowers aren't used many hours per week, but there are a lot of them in America, so that quantity somewhat makes up for the limited hours of use when considering the overall impact. Actually, a few of my neighbors take an awfully long time to cut their one-fifth acre lots. They walk around with that mower engine roaring, seemingly hypnotized by the sound. They cut their loans at a snail's pace, sometimes cutting it this way and then that (two complete cuts) in pursuit of the perfect lawn, I suspect. It takes me about 20 to cut my front and back yards with a non-engine mower. A couple of my neighbors seem to be out their for an hour with the mower and then additional time for the other yard toys. I think that there's a deep psychology of lawn mowing, via the hypnotizing roar of an engine, waiting to be explored.

  8. Erika Price says:

    Alison: You beat me to the punch in pointing out the absurd waste associated with keeping a big, lush lawn. The space, water, the fertilizer, the man-hours pushing a heavy, polluting mower- can the average couch-potato family justify such expense with their limited use of a lawn? The typical family, it seems, hauls out into the backyard once or twice a year for a barbecue, and otherwise leaves their well-manicured lawn to lay out in the sun, unused, for months at a time serving as only a glorified rug.

    In my mid-teens, I dabbled in landscaping work, mowing and clipping and weed-whacking for pay. I mowed for all kinds of people, both the elderly and the able-bodied, the busy and the slothful. It seems to me that very few people even bother to take care of their lands themselves- even lower-middle-class families shell out a needless amount of money so that someone else will take care of their lawn. Instead, these people could purchase a cheap push mower, eschew lawn mowing services and even get some exercise while saving themselves money on gasoline and labor.

  9. Edgar Montrose says:

    Erich: Yes, I am familiar with the activity you describe. My father calls it "manicuring" the lawn. I think it's some kind of primal grooming ritual.

    It takes me a minimum of 75 minutes to cut nearly an acre. In round numbers, figure 40000 square feet in 4500 seconds or 8.89 square feet per second. If each swath of my 22" mower cuts an actual 18" (because of slight overlap), that means that I must PUSH the mower (not self-propelled) at 5.9 feet per second, or 4 mph, the whole time. That's MY snail's pace!

  10. Alison says:

    Erich, I actually found an article when I googled "psychology, lawn mowing," but I didn't want to pay $31.50 to see what it said! I do know that guys and gadgets go together so often that it's easy to assume that the newest, most powerful, loudest, or most numerous yard machines would hold the same kind of appeal for one type of guy as cars or audio equipment might for others. There's got to be something to it – I've had neighbors who would spend entire weekends operating one machine or another even when it was raining, or when the stuff in the yard was starting to go dormant. I used to pass by this itsy bitsy house, with a front yard only about 25 feet wide and maybe 10 feet deep, and see the homeowner mowing it with a ride-on mower. If someone has this kind of feeling towards his machinery, he won't likely be influenced by concern for its environmental impact (or how much it annoys his neighbors. . .)

  11. Vicki Baker says:

    I'm sure Erich could come up with an ev. psych explanation – something to do with our ancestors' preference for open savannah over jungle.

    We know for instance that Native Americans spent a lot of time and effort maintaining open meadow spaces with healthy grass. The largest "lawn" of this type was the Great Plains. Many people today would probably consider their methods quite environmentally destructive.

  12. Erich Vieth says:

    Vicki: Perhaps I could come up with an ultimate explanation — actually, no, I KNOW I could — just give me a quiet place for a few hours and I'll make it look professional! I was actually thinking about a proximate explanation–something to do with the hypnotizing roar of a small engine.

    Or maybe my "proximate explanation" would be the illusion that doing something anything–even something useless or destructive–is more progress than doing nothing (this might have been the main justification for invading Iraq).

    One spouse to the other: "For God's sake, do SOMETHING!"

    The other spouse: "Hey, OK. I'm going to mow the lawn!"

    Really, "motion is progress" is one of the biggest illusions out there.

    "I'm edging the lawn, Damn it!" or "Of COURSE I'm accomplishing something! I'm using the leaf blower to make certain that every molecule of leaf-related matter has been blown over our property line into the yards of our neighbors." And in the process of sterilizing our lawn of dead leaves, I'm soothing my stressed psyche with the roaring of our leaf blower's small rampantly polluting engine!"

  13. Erich Vieth says:

    Marlon: Your photo made me laugh out loud. OK, I'll buy it, but I'll only pay half-price because it's got a quarter inch of rust over the entire apparatus.

  14. Niklaus Pfirsig says:

    We might be walking on dangerous ground with this thread. Back in the 1950's an Egyptian named Sayyid Qotb, was so appalled by what he saw as an American obsession with lawns, that he started the Islamist movement, which advocates the idea of a world government united under Islamic law. The movement is extremely anti democratic, as it assumes that most people are too selfish and greedy to do that which benefits society. The Islamist movement is the driving force in the Middle East against western influence from Europe and America. The beliefs of the Taliban and Al-Queda draw heavily from Qotb's writings.

    It all started with an obsession against lawns.

    Lawns are not as wasteful as many of you think. Lawns stabilize the soil, and help moderate temperature extremes, and the grass on the lawn takes a lot of co2 from the atmosphere and releases oxygen, while acting as a short-term carbon sink.

  15. Erich Vieth says:

    Niklaus: Thanks for the tie-in with Qotb. I learned of him months ago when watching a documentary called "The Power of Nightmares." I didn't know (until you mentioned it) that American lawns had a special place in Qotb's thinking. Here's a post where I did recount some information on Qotb: http://dangerousintersection.org/2006/11/10/terro

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