More than hot air | News | Palo Alto Online |


More than hot air

Research shows health risks in air pollution caused by leaf blowers, but industry disputes implications

• Read Gas-powered leaf blowers are banned from neighborhoods — so why are they being used everywhere?

• Read What to know about 'mow and blow'

Blasting air at up to 185 mph, leaf blowers can whip up hazardous particles and contaminants from the ground at speeds greater than a Category 5 hurricane, sending them long distances.

Epidemiological studies have long recognized the harm these particles — including hydrocarbons from gasoline, animal droppings, spores, fungi, pollens, pesticides and herbicides, fertilizers, brake-lining dust and tire residue and heavy metals — cause to people's respiratory systems, according to Bay Area Air Quality Management District reports.

Exposure to particulate matter is rarely, if ever, cited as the cause of death in a coroner's report when someone dies of a heart attack or stroke or lung disease, a 2012 district study noted. "However, epidemiological studies indicate that exposure to particulate matter is an important contributing factor in hundreds, perhaps thousands, of deaths in the Bay Area each year."

The district has called particulate matter "the air pollutant that poses by far the greatest health risk to Bay Area residents."

The average adult inhales 450 cubic centimeters (roughly one pint) of air per breath, which includes 1 million to 10 million tiny particles with each breath.

"But that figure can spike to much higher levels in close proximity to high-volume roadways or other major outdoor emission sources," the district's "Bay Area 2010 Clean Air Plan" noted.

The contribution of leaf blowers to air pollution isn't to be underestimated. About 5 pounds of particulate matter per leaf blower per hour are swept into the air and take hours to settle, according to a widely cited leaf-blower pollution report by the Orange County, California grand jury in 1999.

An Air District program aimed at replacing up to 50,000 leaf blowers and 10,000 lawn mowers by 2020 would reduce the most dangerous small-particle emissions (sized 2.5 and 10 microns) by 0.12 tons (240 pounds) per day, according to the 2010 Clean Air Plan.

Fine particles measuring 2.5 microns and coarser material measuring 10 microns are more readily absorbed into the lungs. The smaller 2.5-micron particles are associated with hazardous organic compounds and heavy metals, according to the U.S. Environmental Protection Agency (E.P.A.). Particles measuring 10 microns are typically composed of smoke, dirt, dust, mold, spores and pollen.

Particulates in the 2.5-micron range can migrate many hundreds of miles and stay the air for days or weeks; 10-micron particles can travel up to 30 miles and stay aloft for hours, according the U.S. E.P.A.

Besides what they kick up off the ground, gas-powered leaf blowers themselves emit specific pollutants the State of California has identified as of concern: hydrocarbons from both burned and unburned fuel, which combine with other gases to form ozone; carbon monoxide; and toxic contaminants such as benzene, 1,3-butadiene, acetaldehyde and formaldehyde, according to a widely quoted 2000 California Environmental Protection Agency Air Resources Board report.

The Air Quality District in 2010 estimated there were approximately 258,000 two-stroke leaf blowers in the Bay Area, which generate significantly more air pollution than four-stroke engines.

Testing in 2011 by the vehicle reviewer showed just how dirty leaf blowers remain, even 11 years after new emission standards for blowers went into effect.

Pitting leaf blowers against a Ford F-150 SVT Raptor crew cab, the leaf blowers were the big dogs when it came to spewing non-methane hydrocarbons, oxides of nitrogen and carbon monoxide — the three pollutants that the EPA and the California Air Resources Board find most concerning.

The two-stroke blower generated 23 times the carbon monoxide and nearly 300 times more non-methane hydrocarbons as the truck.

"To equate the hydrocarbon emissions of about a half-hour of yard work with this two-stroke leaf blower, you'd have to drive a Raptor for 3,887 miles, or the distance from northern Texas to Anchorage, Alaska," the article noted.

Officials from local lung-health organizations said the contribution of leaf blowers to pollution can't be ignored.

"It should be of great concern," said Lynn Smith, interim executive director of Breathe California of the Bay Area, also noting the huge discrepancy between leaf blower and car emissions.

Various arguments have been made by some environmental groups that blowers should be entirely banned in favor of a return to old-fashioned brooms and rakes.

A 1999 study by the University of California Riverside and San Joaquin Valley Unified Air Pollution Control District, the first of its kind, attempted to quantify the differences. Leaf blowers produced about 30 milligrams per square meter of 2.5-micron-sized particulates and 80 mg per square meter of 10-micron particles.

The results were similar for push brooms used on a concrete surface, probably because of the smoother surface, the researchers found. But using a push broom on asphalt produced no 2.5-micron particles and only 20 mg in the 10-micron range.

And raking on either surface produced no particulates in either range, the study found.

The California Landscape Contractors Association, however, disputes the allegations of the air pollution caused by leaf blowers, calling concerns over air emissions "spurious," according to a 1999 letter from its board of directors that was confirmed as current on July 20.

"Properly used leaf blowers do not raise inordinate amounts of dust. Rule 403 of the South Coast Air Quality Management District states that 'a person shall not cause or allow the emissions of fugitive dust from any active operation, open storage pile, or disturbed surface area such that the presence of such dust remains visible in the atmosphere beyond the property line of the emission source.' Blower users can and should follow this rule," the letter states.

In addition to arguing that emissions standards from the California Air Resources Board implemented in 2000 would significantly reduce emissions from handheld equipment, the association pointed to the intermittent use of blowers.

"Portable lawn and garden equipment contributes only 0.8 percent of all U.S. VOC (volatile organic compound) emissions, 0.6 percent of carbon monoxide emissions, and no nitrogen oxide emissions."

Debates over air pollution aside, there's also noise — perhaps the most evident pollution caused by leaf blowers. The City of Palo Alto requires leaf blowers to emit no more than 65 decibels, when measured from 50 feet away.

The Occupational Safety and Health Administration (OSHA) has determined that decibel levels above 85 cause permanent hearing loss. The World Health Organization recommends a general outdoor noise level of 55 decibels or less and 45 or less for sleeping restfully.

Excessive noise has been implicated in higher heart-attack rates, gastrointestinal disturbances, sleep problems, social discord and psychological problems, according to the U.S. E.P.A.

Ironically, metal rakes aren't much quieter, though the sound is less constant: The City of Palo Alto noted in a 2005 report that metal rakes used on concrete can generate 58-60 decibels at 50 feet.

When it comes to encouraging gardeners to forego their gas-powered machines, one air quality district in southern California has had significant success with its leaf blower exchange. The South Coast Air Quality Management District, which covers Orange County, urban Los Angeles, San Bernardino and Riverside, has held a leaf blower buy-back program since 2006 for professional gardeners. In that time, the district has put more than 12,000 reduced-noise and lower-emissions leaf blowers in the hands of professional gardeners.

The agency distributes about 1,500 new leaf blowers annually, said spokesman Sam Atwood.

"According to the E.P.A., a commercial blower emits 93 pounds per year of air pollutants. Multiplied out times 12,000, the units we have distributed have reduced 500 tons of pollutants since 2006," he said.

So far, the district has distributed cleaner blowers manufactured by the company Stihl. The company has supplied trainings at the exchanges. Operators learn to use the blower like a broom, rolling the debris from one area to another where it can be collected, rather than blasting it in a cloud of dust, he said.

The district helped support the development of backpack electric leaf blowers, which are just now becoming commercially available, he said. Atwood said the district hopes that it will get at least one proposal this year for a truly zero-emission, battery-powered leaf blower as part of its request for proposals.

"In demos, they seem to work very well, equal at least to a gas-powered blower. But it's a little premature to say how they will compare in the field to their gasoline counterparts," he said.

For its part, the Bay Area Air Quality Management District is running a program to fund the purchase of new, battery-powered, zero-emission electric lawn and garden equipment in exchange for gasoline-powered lawn and garden equipment. The program is currently only operating in Alameda and Contra Costa counties, however.

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17 people like this
Posted by Interesting
a resident of Another Palo Alto neighborhood
on Aug 21, 2015 at 8:58 am

I wonder how many people that are so proud of their electric vehicles and "green" lifestyles are still allowing their gardeners to use gas blowers to clean their yards.

Seems a bit hypocritical.

8 people like this
Posted by Resident
a resident of Walter Hays School
on Aug 21, 2015 at 10:47 am

I've been concerned about the regular use of leaf blowers at Walter Hays and wanted to bring up the issue this year, so this is an interesting timing. Almost every morning before start of classes, a "gardener" was going around the school with his blower and sending all this dust into the air, just as the students were arriving at school. This needs to stop, it's not just a question of nuisance caused by noise or energy used by these devices, it's also as the article points out exposing our kids to dust and potentially harmful particles.

10 people like this
Posted by ChrisC
a resident of College Terrace
on Aug 21, 2015 at 2:55 pm

ChrisC is a registered user.

Gas fumes, without dust, come into my second floor apartment. Sometimes I rush to close windows, sometimes I don't. This bothers me more than noise, although the blower used behind our building is deafening. There used to be a city employee whose raison d'être was catching illegal blower activity. He helped stop the 5:30 a.m. Firing up of sleep shattering leaf blowers at the Mormon Institute of Religion on Stanford Ave. BTW- no police were involved. (I thought the city was beefing up it's code enforcement staff.) Also, Menlo Park has a fact sheet in Spanish that can be handed to the mostly Spanish speaking blower operators. I called City Hall once trying to find one for our city, but to no avail. Might there be a follow-up to this story with information ab

1 person likes this
Posted by ChrisC
a resident of College Terrace
on Aug 21, 2015 at 3:01 pm

ChrisC is a registered user.

Continuing...information regarding any new or existing enforcement procedures. Ten years ago I just phoned "the enforcer." all one had to do was tell him the address and the time he was likely to catch them. Another idea: couldn't we report the address to city hall and couldn't they send a letter to the owner quoting the ordinance and saying there had been a report filed? Isn't that what we can do to report exhaust belching vehicles to the state?

Like this comment
Posted by Jocelyn Dong
editor of the Palo Alto Weekly
on Aug 21, 2015 at 10:00 pm

Jocelyn Dong is a registered user.

ChrisC - The City does plan to hire a new code-enforcement officer. Among this person's tasks will be "supporting" the police department in enforcement of the leaf blower ordinance, according to Planning Director Hillary Gitelman. See our main article on the ordinance here: Web Link

As for what can be done now, the City has an online site (and app called PaloAlto311) through which residents can file complaints about a range of problems, including gas leaf blowers: Web Link Photographing or reporting the license plate number of the gardener's truck could help the police identify repeat violators of the ordinance.

9 people like this
Posted by Klara
a resident of Charleston Meadows
on Aug 22, 2015 at 1:31 pm

Thank you for writing this very informative wake up call article!

I'm advocating for years to ban the leaf blowers for the same reasons mentioned.

It is should be not just the Police's job to enforce the Ordinance and issue a fine for $ 100. This is not productive at all!

The Gardener's Licence should be revoked if continues to use the blowers.

4 people like this
Posted by reg
a resident of Atherton
on Aug 22, 2015 at 1:37 pm

Leaf blowers do have mufflers. How about doing something about all the motorcycles that are lacking mufflers, and have had their emission systems altered so that they are running dirty?

3 people like this
Posted by Innovative answers
a resident of Green Acres
on Aug 24, 2015 at 9:02 am

Hmmm. This is Silicon Valley. Why hasn't someone made a robotic rake? And outdoor Roomba that follows the robotic rake and gets smaller stuff, not by blowing and filtering (for air) but by a convered contained whirlwind that could potentially filter some nasty stuff? (Gardeners might be careful complaining about the raking themselves.)

7 people like this
a resident of Gunn High School
on Aug 24, 2015 at 10:15 am

[Post removed.]

5 people like this
Posted by Curmudgeon
a resident of Downtown North
on Aug 24, 2015 at 11:00 am

'Poisoning the air is legal in Palo Alto if you do it electrically. Case closed.

7 people like this
Posted by inmby
a resident of Downtown North
on Aug 24, 2015 at 11:40 am

[Post removed.]

10 people like this
Posted by VACUUMLeavesInsteadOfBlow
a resident of Downtown North
on Aug 24, 2015 at 11:56 am

I would like to suggest to require gardeners use VACUUMs/MULCHERS and to BAN BLOWERS. See Web Link.

1 person likes this
Posted by Hooray
a resident of Another Palo Alto neighborhood
on Aug 24, 2015 at 12:23 pm

As the Aussies say, there's a bonzer gem--a grand idea!

Very tempted to buy one or two for my gardener.

9 people like this
Posted by Innovative answers
a resident of Another Palo Alto neighborhood
on Aug 24, 2015 at 12:27 pm

" dont want leaf blowers around, do your own landscaping , hmmmm, thought not "

Actually, in rentals, we always offered to pay the difference for raking to avoid leaf blowing, and even when it got set up and we were paying more, the services would inevitably forget.

One of my top enjoyments of having our own home again was to NOT hire someone mainly so we could avoid the leaf blowers.

Did you even READ the article?? Ever heard of "asthma"? I agree with inmby, enough of this name calling of people trying to keep our town healthy and a nice place to live. You sound just like the tobacco companies and their lackeys/addicts/adherents when it came to smoking. Your counter to scientific evidence is nastiness and namecalling. Enough already.

9 people like this
Posted by Nayeli
a resident of Midtown
on Aug 24, 2015 at 1:03 pm

Nayeli is a registered user.

When the gardeners come to our apartment to blow leaves, our apartment becomes a nightmare! Like many people in Palo Alto, we do not have an air conditioner. We rely upon open windows (and a couple of window fans) to cool our home. When the gardeners arrive (typically unannounced), they blow leaves near every windows. However, they are also blowing in fumes from their leaf blowers. If the fan is on (which is usually is), the fumes funnel into our home very quickly.

We usually are forced to take off the fans and close the windows and quickly depart the premises. It is bad for me (usually results in a headache from the fumes) and I know that it is bad on my child.

I am not necessarily saying that leaf blowers should be banned. However, there should be a rule that individuals with open windows be warned prior to a leaf blower being used near their open doors or windows. At least this would give us the opportunity to close our windows BEFORE a leaf blower is turned on next to us.

7 people like this
Posted by Not a PA resident
a resident of another community
on Aug 24, 2015 at 1:44 pm

I totally agree - no gas and electric blower, no leaf blowers at all. Only vacuums to be used for outdoor cleaning.

This problem is not a problem only for Palo Alto residents, it is a problem for who comes to work in the town.

I hate to breath dust around leaf blower even though the gardeners are very kind to stop when a pedestrian is around. Also, I hate, I hate when my car gets dirty the first day after I washed it. Thanks God I do not have allergies.
So, thank you for the discussion, and I will appreciate it if City of PA permits only vacuums for outdoor dirt. I think the first vacuum was invented for outdoor cleaning in UK. So, nothing new, just let's stand for it.

3 people like this
Posted by mauricio
a resident of Embarcadero Oaks/Leland
on Aug 24, 2015 at 3:37 pm

mauricio is a registered user.

All these health risks had been known ten years ago, yet the council legislated a very weak, pretty unenforceable ordinance that didn't deter anyone from using gas leaf blowers. The most pathetic thing is that on save the air days, gardeners are using gas blowers freely and with impunity.

5 people like this
Posted by Jim H
a resident of Community Center
on Aug 24, 2015 at 5:21 pm

If you would like to get involved in getting rid of leaf blowers in Palo Alto, please get in touch with me at

Even if you do not wish to actively participate, we could keep you alerted to progress on this issue.
I will not use your email address in a mass mailing, just to get back to you.

9 people like this
Posted by Sunshine
a resident of Barron Park
on Aug 24, 2015 at 5:28 pm

There was a time, I moved here then, when people did not use leaf blowers.
Palo Alto should ban ALL leaf blowers. They all blow noxious, dangerous particles into the air. There is nothing wrong with using a rake. It is better for your cardio fitness and easier on everyone's hearing.
All leaf blowers are bad for our lungs.
Let's ban them now and enforce the ban for a change.

Like this comment
Posted by PaloAAAlto
a resident of Midtown
on Aug 24, 2015 at 9:27 pm

I would like to suggest that people start using the old (non-motored) lawnmowers with just a spinning set of blades. It feels quite good/rewarding feeling the vibration(s) of the grass when it is cut using this instrument. :)

Like this comment
Posted by Member
a resident of Fairmeadow
on Aug 25, 2015 at 7:32 am

Ran by Eichler Club on Louis Road a few minutes ago. Leaf blower was blowing at 7:10am!

Like this comment
Posted by Midtown
a resident of Midtown
on Aug 25, 2015 at 7:44 am

Go with the Santa Monica solutions: fine the home owners when a gas blower is used. Send out citations based on photo evidence from cell phones. Solved the problem in Santa Monica in several months.

Like this comment
Posted by Greg M. Bell
a resident of Midtown
on Aug 27, 2015 at 5:26 pm

Leaf blower noise, the gasoline pollution and dust in the air are all concerns to me. These issue are not healthy for the operators either.

2 people like this
Posted by Wildman
a resident of another community
on Aug 27, 2015 at 6:36 pm

For the people operating the leaf blowers, it's a choice between 2 minutes of leaf blowing vs. 20 minutes of raking. Which would you choose?

If you want to get your way, make it look like a safety issue. OMG, it's a HURRICANE! RUN FOR YOUR LIVES, EVERYONE!

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