How to Reduce The Environmental Impact of Mowing Your Lawn

Mowing your lawn for an hour is equivalent to driving 150 kilometers (93 miles), at least in terms of polycyclic aromatic hydrocarbon emissions. This is according to a Swedish study examining the impact of typical four-stroke, four horsepower lawn mowers.

For the average American, who spends 25 hours a year mowing the lawn, this works out to about 3,750 km of driving.

This just goes to show that the environmental impact of lawn mowers can really add up.

So, if you’re already concerned about the carbon footprint of your driving, it’s also worth looking at what’s lurking in your shed.

Are mowers really all that bad?

Fortunately, things have improved (a little) since the Swedish researchers ran their tests more than two decades ago.

For one thing, the U.S. Environmental Protection Agency (EPA) implemented new regulations to curb emissions from smaller ‘non-road’ engines. Their first stab at this was actually back in 1998, with ‘Phase I’ rules mandating a 32% reduction in emission from these engines.

The EPA brought in these regulations because data showed that almost 9% of some types of air pollution were due to:

• Lawn mowers
• Leaf blowers
• Chain saws
• Other garden equipment.

Phase 3 exhaust emissions standards took effect in 2011 or 2012, depending on the size of the engine. These standards have further helped to reduce emissions, but the fact remains that gas powered lawn mowers produce far more emissions than electric lawn mowers, even when accounting for upstream emissions from power plants.

Air pollution from gas lawn mowers

Older two-stroke engines are terribly inefficient at turning gasoline into energy. In fact, about 30% of engine fuel fails to undergo complete combustion in such engines.

That incomplete combustion produces high amounts of air pollutants, including:

• Methane – a powerful greenhouse gas
• Carbon monoxide – a colorless, odorless, poisonous gas
• Nitrous oxide
• Hydrocarbons – including known carcinogens.

NO and hydrocarbons also cause smog.

Other emissions from lawn mowers include ethane, ethene, ethanol, and:

• Particulates – microscopic airborne particles that contribute to smokiness and that gas mower smell; these also damage the respiratory system, causing breathing difficulties, especially in infants, seniors, and anyone with pre-existing health concerns

• Carbon dioxide – a greenhouse gas that contributes to climate change
• Nitrogen oxides – which contribute to acid rain and react with hydrocarbons in the atmosphere to form ground-level ozone that can damage lungs.

Oh, the irony – gas mowers can emit pollutants that cause acid rain that damages infrastructure, buildings, wildlife and vegetation, including your lawn.

Air quality

Cities with lots of auto-rickshaws with two-stroke engines have some of the worst air pollution and heavy soot. This was the case in Delhi, in India, before the wider adoption of four-stroke engines, which has helped lower smog levels.

Unfortunately, as some cities take steps to reduce small engine pollution, others are seeing an uptick from increased use of gas-powered leaf blowers and snow blowers. This creates a double whammy for respiratory health:

• More air pollution
• Less physical activity to clear snow and leaves.

In the US, all gas mowers sold since 2012 should meet the CARB/EPA 50-state emissions standards for emissions. Some mowers exceed these standards, which further lowers emissions and keeps your running costs low.

For example, Honda consistently exceeds requirements for small engine emissions, which is why I tend to favor Honda for my top picks for gas mowers.

Still, the best lawn mower for reducing air pollution is one with no tailpipe emissions at all. And that means either going manual or going electric, ideally powered by renewable energy.

Are electric lawn mowers really better for the environment?

Electric mowers are quieter and better for the immediate environment (i.e., your back yard) than a gas guzzling mower.

Are they really eco-friendly, though?

That depends.

If the electricity that runs your lawn mower is green, you’re onto a winner. If your electric mower battery or corded mower uses energy from coal -burning power plants though, the pollution is just out of sight, upstream.

That said, even an electric mower powered by fossil fuel derived electricity is still ‘cleaner’ than a gas mower. The same is true of induction and electric stoves versus gas stoves.

This is because power plants are far more efficient than small engines at using carbon-based fuels and have a range of mechanisms in place to reduce and capture emissions (although these standards are being eroded in the US currently). Using electricity also totally eliminates the risk of fuel spills and gas emissions in your back yard.

Going greener

Ideally, your electric mower will be both energy efficient and powered by clean energy. In practice, this means:

• Being able to choose a clean energy provider
• Pressuring government to implement more robust clean energy policies
• Setting up a micro hydro system, wind turbine, or solar panels to charge the batteries. 

To save on your gym membership and get real green, you could also use a reel mower like the Earthwise 16-Inch Reel Lawn Mower. This is designed to cut Bermuda and Zoysia grass and produces no emissions at all.

In my experience though, this kind of manual mower does produce a lot of noise pollution in the way of expletives. Cutting a decent sized lawn with a reel mower is hard, hot, thankless work. Definitely don’t try this at home if you have a lawn bigger than 10,000 square feet, unless you’re a masochist.

The downside of electric mowers

Before wrapping up, it’s worth mentioning one major downside of electric cordless mowers: dead batteries ending up in landfill.

Sadly, simple economics mean most dead batteries are usually frozen, crushed, and sent to landfill.

The chemicals in lithium ion batteries aren’t a big cause for concern when this happens (unlike older lead acid batteries). Nonetheless, dumped rechargeable batteries contribute to waste in landfill. And resource extraction to produce new batteries is a problem in itself.

Depending on where you live, you may be able to take your old batteries to be recycled. Check with your local government office or look for recycling services locally.

Aside from the environmental impact of lawn mowers, there are, of course, plenty of other things to consider when buying a new lawn mower:

• Power, battery run-time, and charge time
• Cutting deck width and size
• Noise and vibration
• Wheel size
• Drive function
• Cutting height and adjustments
• Storage.

These are all key factors that can mean you love or hate your mower. Happily, four years on, I still love my electric mower, and there’s no way I’d go back to gas (or that infernal reel mower!).

See my recommendations for the best electric mowers and gas powered mowers.