leaf blowers zero air pollution
research regarding leaf blower laws

Distribution of Contaminants in Polluted Air

Emissions and Fuel Spills


Fugitive Dust

Particulate Matter

Noise is an Emission, Too

ANSI Standards

Decibel Table

About 8 printed pages.


Causes: Distribution of Contaminants

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Exhaust emissions, fuel spills, and fugitive dust contaminants (all of which contribute to air pollution) and noise from blowers can all impact overall health, from subtle changes in well being to death.  Air pollution includes both smog and air toxics, which are chemicals that may not be considered safe at any level, (97.7.10) and which are known to cause cancer, or lead to other critical illness.  Noise can cause hearing loss, interfere with communication, cause rest and sleep disturbance and changes in performance and behavior, and other psychological and physiological changes that may lead to overall poor health. (ARB Report)

“Potential health effects from exhaust emissions, fugitive dust, and noise range from mild to serious.” -- ARB Report

We recommend “Poisoning the Air: Airborne Pesticides in California”, CALPIRG/ Californians for Pesticide Reform, by Zev Ross and Jonathan Kaplan (IGC), or see their homepage, to learn more about pesticides.

The Zero Air Pollution four-minute Video shows the dust drift caused by blowers, and describes the Orange County Grand Jury Report, that recommended blowers not be used.  The written Video transcript is available on this site.

Blowers create an illusion of usefulness

Polluted Air
In Los Angeles and nearby counties, according to the Air Quality Management District, “thermal inversions act like a lid over the basin. Bright sunshine and warm temperatures cause some pollutants to react with each other, forming even more pollution . . .. Different types and levels of air pollution can cause everything from watery eyes and fatigue to respiratory disease, lung damage--even cancer.”  See Maps of specific pollutants in LA or your own area. (Source).

A Natural Resources Defense Council report estimates that, in the Los Angeles-Long Beach, California area alone, in 1989, Adult Cardio-pulmonary deaths attributable to Particulate Air Pollution were between 3,550 and 7,933.  “The Breath-taking report estimates that approximately 65,000 premature deaths from cardiopulmonary cause may be attributable to particulate air pollution each year.”

Joel Schwartz, Harvard School of Public Health, “You find people dying from chronic lung disease, pneumonia, and sudden heart attacks. These aren’t people [already] lying in the hospital with tubes stuck in them.  The biggest increase we find on high air-pollution days is in people dead on arrival at the hospital” and:

Linking environmental pollution to specific disease is overwhelming, but studies linking it to poor health are consistent, with significant results.   In response to stronger air pollution standards, “Industries have launched a direct attack on the science itself.”  (97.8.1) We recommend this whole Consumer Reports article, August 1997 “Clearing the Air, Is Our Air Clean Enough?”

Polluted air “Reduces the capacity of red blood cells to carry oxygen to the body.  It promotes and aggravates heart, blood and other diseases. . .Alters behavior and may decrease mental performance; Brings on headaches and irritability.”  (96.11.2)

“A lot of our pollution comes from the products and services we use every day.  All of us can help by making some simple changes in the way we live.” and, “Ozone, the worst ingredient of smog, is not emitted directly into the air from any source.  It is formed when two other pollutants – hydrocarbons . . .and nitrogen oxides—react in sunlight.” (96.11.2)

“A large body of research has proven that people suffer serious health effects at pollutant levels below the current standards.”  (CEHN Source)

“Air toxics are chemicals that may not be considered safe at any level.  they are known to cause cancer, or lead to other critical illness, birth defects or genetic mutations.  One example is benzene, a component of gasoline, which has been linked to leukemia”  (96.11.2)

“The American Lung Association recommends that passersby avoid blowers if possible, especially if they suffer from respiratory problems” (98.11.1)

Toxic matter widely distributed by blowers may settle, unseen, on infant and children’s outdoor play equipment and toys, which are often sucked on by those children.  It may drift or be drawn inside their homes with the same results.
Emissions And Fuel Spills
The Federal Environmental Protection Agency (EPA) and the State Air Quality Resources Board (ARB) are charged with protecting the health of all residents of California.  They have waged an uphill struggle to reduce air pollution from all sources, not just motor vehicles.  This makes sense, when you consider that only 50% of our air pollution comes from these vehicles.  By 1997, their efforts resulted in 70% reduced pollution by industries, and automobiles were running more than ten times cleaner than in 1966. (97.7.10) Around this time, the AQMD began to emphasize pollution from millions of everyday single uses of consumer products.

The AQMD is charged with regulating “utility” engines, also known as “non road” engines, which include lawn and garden equipment.  A July 1997 AQMD report states, “Commercial equipment is responsible for the lion’s share of 14 tons per day of smog-forming volatile organic compounds emitted by all lawn and garden equipment in the Southland.” (97.7.10)

An Air Resources Board report on the health and environmental impacts of leaf blowers points out, “Exhaust emissions from leaf blowers consist of the following specific pollutants of concern:  hydrocarbons from both burned and unburned fuel, and which combine with other gases in the atmosphere to form ozone; carbon monoxide; fine particulate matter; and other toxic air contaminants in the unburned fuel. . ., including benzene, 1.3-butadiene, acetaldehyde, and formaldehyde.”. (ARB Report)  While manufacturers have made great improvements, in some cases even meeting or exceeding standards not yet in effect, older machines still in use are of concern.

Toxic compounds in gasoline are carcinogens; e.g. benzene has been linked to leukemia (96.8.2).  At low exposures, carbon monoxide causes headaches, dizziness, weakness and nausea.  Ozone can cause constriction of airways, coughing, sore throat and shortness of breath.  “Acetaldehyde is a probable human carcinogen . . .and acute exposures lead to eye, skin, and respiratory tract irritation. 1,3-Butadiene is classified as a probable human carcinogen, is mildly irritating to the eyes and mucous membranes, and can cause neurological effects at very high levels. Formaldehyde is highly irritating to the eyes and respiratory tract and can induce or exacerbate asthma. It is classified as a probable human carcinogen.”  (ARB Report)
Irritating to Living Tissue

(Source p.4 of 7)
Since 1995, when initial standards were set, however, manufacturers “have done an acceptable job certifying and producing engines that are below the regulated limits.”  By 1999, “Exhaust standards already in place have reduced exhaust emissions from the engines used on leaf blowers, and manufacturers have significantly reduced CO [carbon monoxide] emissions further than required by the standards.”  In addition, new designs and methods of refueling have reduced fuel spills, and their resultant pollution.

Even so, “Ultra-low or zero exhaust emitting leaf blowers could further reduce public and worker exposures.”  What is an “acceptable job” to the ARB may be lacking to environmentalists and health care professionals, but it is a step forward.

It must also be remembered that air pollution standards are set amid much uproar from manufacturers, other related businesses, and the politicians they influence.  The standards achieved by manufacturers may still be set far below what would most benefit the health of state residents.  In efforts to avoid economic hardship for manufacturers and distributors, safer emission and pollution standards may be phased into effect only over a number of years.
Air Quality: 

Fugitive Dust
Historically referred to by many families as “Dust and Grime”

Some people may experience severe respiratory or other reactions from the distribution of dust, alone.  The term “fugitive dust” accurately describes the dust and fine debris distributed by the powerful air velocity of blowers.  Once airborne, it cannot be controlled.  It is a mixture of many pollutants propelled from landscape and hardscape alike (patios, decks, walkways, driveways, sidewalks, gutters, streets).  Especially where blowers are used on residential landscape and hardscape, it may contain dried fecal material, fertilizers, fungal spores, mold, pesticides, and herbicides.

Blowers are designed to move relatively large piles of leaves and debris.  In efforts to satisfy customers, manufacturers promote blowers with “more power”:  i.e. higher air velocity, which equals a greater distribution of fugitive dust and Particulate matter.  This air speed may be up to 120mph.  Hurricane winds start at about 117mph.  Where only “gasoline blowers” are banned or restricted, yard workers look to alternative fuels and for more power in the electric models.  This defeats the intent of restrictive laws, which is cleaner air.

The ARB 2000 Report states “Banning or restricting the use of leaf blowers would reduce fugitive dust emissions.”  Many air quality districts prohibit the generation of dust which becomes visible in the atmosphere beyond the property line of its generation. 
Air Quality

Particulate Matter (PM)

Smog has long been recognized as a danger to health.  Only recently has Particulate matter, which is a part of the dust made airborne by blowers, been recognized as even more of a danger. 

Particulate Matter (“PM”) contains both fine and coarse particles, all of which are re-suspended into the air over and over again by blowers.  They may remain, unseen, in the air we breathe for hours to days at a time.  Even when below current standards, PM is associated with increases in mortality and morbidity.

“Coarse particles” come from paved road dust, and are a major contributor to airborne PM in Los Angeles.  Road dust may contain small amounts of toxic metals arsenic, chromium, lead and mercury, as well as soil, tire and brake particles and allergens (including pollens, pollen fragments, animal dander and molds) which can cause or intensify allergenic disease.” (ARB Report)

PM may contain carbon, soot, sulfur (97.7.2), lead.  Coarse particles are also formed by ammonium nitrate. (97.11.3)

“Fine particulate matter (PM10) . . .(finer than a human hair), takes the form of either liquid droplets or solids.  The particles are mixtures of man-made and natural substances including sulfates, nitrates, metals, carbon, rubber, sea salt, soil, soot and organic material.” (96.11.2)

“We know that breathing fine particulates causes premature death.” (97.7.10)  It now seems probable that fine particles are more toxic than coarse particles.  It may help that manufacturers have reduced the emissions of new blowers in the past few years.

When blower advocates point out that it also contains dried animal feces, it usually triggers an “E-e-e-u-u-w-w-w!” response from listeners.  “Here’s the poop on pigeons.  They carry and transmit diseases such as encephalitis, salmonella and histoplasmosis. They’re loaded with ectoparasites like fleas, ticks and mites. . .” (98.12.2) 

Because some people have expressed the fear that hantavirus found in the urine leavings of rats could be spread by blowers, ZAP sought information from James N. Mills, Ph.D, chief, Medical Ecology Unit, at the CDC. He was gracious enough to give us a full explanation. Because the blowing air would dissipate the virus, and it would likely be exposed to ultraviolate sun, it is very unlikely to be spread by blowers. The power of the virus decreases rapidly once outside the rodent's body, and doesn't last more than two or three days. It is more likely spread by exposure to enough of the urine, especially at the site of broken skin or eyes, in a shaded or dark environment where there is an active infestation of infected rodents. That situation does not match up with common residential landscape maintenance practices.

He does, however, recommend blower operators wear hepa/N100 filtered face masks (for small particle aerosols), wrap-around goggles, and protect areas of broken skin.

No studies have been done on the impact of blower use on the spread of pesticide residues.  However, there is a widespread use of pesticides in California, and “the use of pesticides on home lawns is heavier than comparable area use in agriculture.” (The Ecology of Eden)  A USGS survey of air monitoring studies shows airborne pesticides travel far from their original source. and. . .”. . . may pose significant risk particularly to pregnant women, children or chemically sensitive/immune system compromised individuals.” (Poisoning the Air report, p.3)

Between 1991 and 1995, use of cancer causing pesticides more than doubled.  Some pesticides break down very quickly.  Others adhere to soil or dust particles, or vaporize, and could easily be blown, along with dust and gasoline fumes, right into neighboring homes.  Symptoms of exposure, such as nausea, vomiting, and/or headaches, could be mistaken for the flu. (Poisoning the Air report, p.12)

The things we don’t know could be harmful to our health.  No “safe” levels for exposure to a combination of pesticides and chemicals have been identified.  The results of low exposures over long periods of time need to be studied. 

“Chronic toxicity [of pesticides] refers to long-term health effects that occur months or years after the toxic exposure. Health effects may be delayed consequences of past exposures, or a result of continuing low-level exposures over time. Effects can include respiratory problems, cancer and other tumors, neurological damage, and reproductive effects such as birth defects, stillbirth, spontaneous abortion and infertility.” (Poisoning the Air report, p.11)

Compared with short term effects:

“Acute Toxicity of Pesticides:  Acute toxicity refers to short-term adverse health effects that occur after recent exposure to the toxic substance. Usually this is within a few minutes to a few hours—at the most a few days. Effects can include: stinging, burning, rashes, blisters, scarring, blindness, convulsions, nausea and dizziness.”  (Poisoning the Air report, p.11)
“Noise is an emission, too!”
Noise:  any unwanted sound:  probably loud, unmusical, and disagreeable, with potential of causing hearing loss and other adverse health impacts.  In addition, the quality of the noise has a bearing.  High pitched sounds, whatever their volume, may be “noise” to sensitive individuals. 

“. . .there is a growing recognition that continued noise exposure can trigger physiological changes in blood pressure, sleep, digestion, and other stress-related disorders.” (01.3.2)

Where unwanted airport noise levels reach 65 dB, as monitored continuously in Westchester, Play del Rey and South Los Angeles, about 9,000 residences are eligible for funds for soundproofing; dual-paned windows, solid-core doors and attic insulation.  The quietest gas blower on the market at the time this web site was created, claimed to be 65 db by ANSI standards – which are explained below.

Los Angeles has noise restrictions on machinery used in or within 500 feet of any residential zone of the City.  “Powered equipment intended for repetitive use in residential areas, including lawn mowers, backpack blowers, small lawn and garden tools and riding tractors . . .” (Section 112.05 LAMC) including electric blowers, which are not banned, are restricted to a maximum of 65 decibels at 50 feet.  This is a standard that few gas blowers operated in residential neighborhoods could meet. 

Los Angeles blower supporters requested a “compromise” of banning only blowers that registered over 65 decibels by the American National Standards Institute, Inc. (“ANSI” herein).  The ANSI Accredited Standard Committee, which developed the method for measuring blower sound, includes blower manufacturers and trade associations.  We applaud their interest in finding a workable standard that, at least, gives consumers a formula for comparison-shopping amongst various models and manufacturers of gardening equipment. 

The method of testing, however, does not represent actual sound levels resulting from blower use in residential areas, and leads to erroneous conclusions on the part of lawmakers.  The ANSI sound test score, an average of several readings taken at a distance of 50 feet, may have been explained to them as “normal conversation level.” 

When advised that a new machine on the market is “65 decibels”, press and politicians frequently conclude that is the same level of noise heard by all people who are within hearing range of the machine.  They also may conclude that the machine with the lowest standard possible is the only one that will be used in a typical neighborhood.  In addition, the ANSI dB label on new machines may not represent the noise level of that machine as it sounds after a period of use, particularly if it is not well maintained. 

ANSI STANDARD: Also referred to as "Industry Standards."

The ANSI tests take place in an open field, with ground cover lower than 3 inches, and where large reflecting surfaces (such as property-line fences and walls, houses and cars) must be at least 100 feet from the blower.  The sound meter microphone is 50 feet from the operator of the machine and four feet above ground.  Eight readings are taken in a circle every 45 degrees as either the operator rotates, or the microphone is moved.  The eight readings are then averaged to the nearest decibel.  They are set to “A” for weighting, which evaluates high or low frequencies.

Average, remember, is neither the lowest, nor the highest reading.  One very low reading can bring down other fairly high readings.  When a blower is five feet from an open window of one’s home, blowing between and echoing off the neighbor’s stucco house exterior and a cement wall, the noise entering one’s home is not averaged, it is direct and may be much higher than 65dB.

Doubling the distance between the source and the person hearing a sound drops the sound level by approximately 6 dB.  With the logarithmic scale used to rate noise, 80 dB is 10 times as loud as 70dB.  90dB is a hundred times as loud. (Source).  Since sound pressure levels are not directly additive, see the ARB 2000 Report (Source) and/or go to noise pollution web sites (Noise Pollution Clearninghouse and National Institute on Deafness and Other Communication Disorders) to figure out what this means to listeners who are closer than 50 feet, or for machines with decibel levels higher than 65. 

For comparison of sounds which, when controlled or chosen by a listener, are acceptable, but which become “noise” when unwanted and/or unexpected, consider the following table: 
Note: These decibel level comparisons may refer to the levels of older appliances, not the quieter versions available today.
45dB Maximum level for uninterrupted sleep (World Health Organization)
45-70dB Moderately Loud. 75-95dB Very Loud.

About 25% of people will be awakened or delayed in falling asleep (Human Factors)

Light traffic, Normal conversation, quiet office. (Sony headset brochure)

50-60dB Quiet Office (WISE)
50-65dB Normal conversation (WISE)
55dB Upper acceptance level for spaces where quiet is expected.  People will have to raise their voices slightly to converse over distances greater than 8 feet.  Will awaken about half the population about half of the time. Still annoying to those sensitive to noise (Human Factors)

Dining, social conversation (Human Factors)

Air conditioner at 20 feet, sewing machine (Sony)

60-65dB Laughter (WISE)

A generally noisy environment, sporadic conversation is acceptable.  About half the people will experience difficulty sleeping (Human Factors)

Only one or two newer blower models, at 50 feet.

68dB Top level for telephone conversation without difficulty (Human Factors)

Vacuum cleaner, hair dryer (WISE)

The upper level for normal conversation, even when close together.  At six feet, must shout.  Telephone conversation will be difficult. (Human Factors)

Noisy restaurant (Sony)

75dB Dishwasher (WISE)

Too noisy for adequate telephone conversation.  A raised voice required at a distance of two feet apart.  (Human Factors)

Recreational vehicle

LEAF BLOWER at your next door neighbor's.


Garbage disposal (WISE)

Conversation is difficult, must be in a loud voice less than one foot apart.  It is difficult to think clearly after about an hour, there may be some stomach contraction and an increase in metabolic rate. ( Human Factors)

Average city traffic, alarm clock at two feet (Sony)

88dB Subway or motorcycle


Up to 110 dB or more

Lawnmower (WISE)

Some blowers, next to operator's ear.