Can You Hear the Difference Between High- and Low-Frequency Sound? Find Out With This 18-Second Test

In his testimony for the Washington D.C. City Council on June 2, 2018, Chris Pollock, of the Arup consulting firm, presented the results of Arup's original acoustics research, on the sound properties of different kinds of outdoor equipment. 

The most significant part of his statement concerned the surprising difference between the official loudness rating of leaf blowers--say, 75 decibels--and how the machines actually sound.

The difference turns on the contrasting acoustic properties of gas- and battery-powered machinery. Gas-powered blowers with two-stroke engines, the most familiar (and dirtiest) models, produce dramatically more sound energy in the low-frequency spectrum.

This might seem benign, since people associate high-frequency noise with a dental-drill-style annoying whine. But low-frequency waves are in fact more intrusive and nuisance-creating. They travel much farther than high-frequency waves; they penetrate walls and barriers; and they mean that the noise-footprint of a gas blower covers a vastly larger area that a battery-powered machine with the "same" loudness rating. This explains the common-sense observation that neighbors can tell from many blocks away when a crew with gas-powered blowers begins its work.

Here's the data-based, researcher's way to convey that point, as Pollock put it in his testimony:

From the data above, we observe that clearly the group of gas leaf blowers all exhibit a much higher level of sound energy in the low-frequency bands....Based on our experience measuring sound, I witnessed that the three gas-powered leaf blowers at an 800-foot distance were audible, two being clearly audible, the RedMax EBZ8500 and the Stihl BR700X. And the third, the ECHO PB-760, being noticeable. While the battery-powered blowers at that same distance were not distinguishable above the very quiet community sound levels at that distance.... 

Low-frequency noise requires heavy construction and materials to stop sound transmitting from the outside of the building to the inside...The sound levels of gas leaf blowers are measured inside the house are significantly above those of the battery-powered leaf blowers, even when both of the leaf blowers are rated at the same decibel level at 50 feet. 

But a simpler way to grasp the difference may be to listen to the 18-second sound clip below, from the Arup experiments. It's of two blowers that officially have the "same" loudness rating, measured at the same distance.

The first eight seconds are a battery-powered machine, with a distinctive high whine -- but a sound that falls off very rapidly with distance. If this machine were running outside a building, you might not hear it inside.

The second sample is of a gas-powered machine.

See if you can notice the difference! 

One More Advisory Neighborhood Commission Endorses the Bill, Bringing the Total to 14

Over the past two years, Advisory Neighborhood Commissions across the District of Columbia have been voting in favor of Bill 22-234, to phase out noisy, polluting gas-powered leaf-blowers within the District and shift to quiet, clean battery-powered models. (ANCs are elected neighborhood bodies across the District, which have some local jurisdiction and report to the City Council.)

This month ANC6B, which represents Capitol Hill and parts of Southeast Washington, voted in favor of this bill. Its admirably to-the-point endorsement statement is below.

This makes 14 ANCs that have now endorsed the bill. They represent the overwhelming majority of the ANCs that have considered it; more than one-third of all the 40 ANCs that exist (no ANC has opposed it); and coverage from all parts of the city, seven of the eight total wards, reflecting a broad sampling of DC's population. 

For testimony from a hearing before the City Council's Committee of the Whole, on July 2, 2018, please see this full transcript, and this summary introduction.

Thanks to ANC6B and the 13 other ANCs that have weighed in.

Full Transcript of City Council Hearing on Mary Cheh's Leaf Blower Bill Now Available Online

Through the past three years, this site has reported on the progress of legislation to phase out noisy, obsolete, hyper-polluting gas-powered leaf blowers in the nation's capital city, and to phase in quiet, clean battery-powered equipment.

Council Member Mary Cheh has introduced legislation to that effect; Advisory Neighborhood Commissions across the District have endorsed it; and a majority of City Council members have indicated their support.

The crucial next stage of "how a bill becomes a law" was for hearings on the bill by the Council's "Committee of the Whole," whose membership includes the full Council (but which, for procedural reasons, must consider the bill before the whole Council does).

Those hearings, over which Council Chair Phil Mendelson presided, took place on the afternoon of July 2, 2018. As Council members themselves observed, they turned out to be an entirely lopsided contrast of perspectives. 

On the pro-bill side, witnesses produced brand-new and significant acoustic evidence, showing that the sound properties of noise from gas-powered blowers were fundamentally different from those of the battery models, and in a way that made their noise far more disturbing and damaging. (Short version: the gas-powered models produce dramatically greater spikes of low-frequency sound waves, which seems as if would be less annoying than a high-frequency whine. But in fact low-frequency waves travel much greater distances than high-frequency sound waves, and can penetrate walls and windows. The US Navy uses ultra-low-frequency waves to communicate with its submarines when they are beneath the surface, precisely because these waves can travel so far.)

Thus if a gas- and a battery-powered blower have the "same" loudness rating, say of 75 decibels, the gas-powered blower is in fact far louder. The difference is much like the role of humidity in summer weather readings: an 88F degree day in Washington DC, with sweltering humidity, feels much hotter than an 88F degree day in Denver, with bone-dry air. As one expert, Dr. Jamie Banks of Quiet Communities, testified, the noise footprint of a gas-powered leafblower can cover a vastly greater area of a neighborhood than that of a "similarly" loud battery-powered blower. Her testimony explains the significance of the graph below:

The owners of some lawn-maintenance companies also testified for the bill, saying that they had successfully switched their businesses to battery-powered operations. A leading technology writer said that all previous clean-tech legislation, whether it was the switch away from leaded gas or the ban on DDT, had met initial industry opposition as being "impractical," "bad for business," and "intrusive." But after it took effect, people asked, Why did we wait so long?

Citizens and representatives of neighborhood groups talked about the effect that rising levels of ambient noise had on community life and personal health. A career lawn-care worker described the way exposure to gas-powered leaf blowers had deprived him of his hearing.

For their part, the two industry-lobbyist representatives made points that their counterparts have made for decades. One was that the proposed shift would be ruinously expensive for lawn-care companies--despite the testimony of real-world gardening companies that have already made the change successfully. The other was that the "solution" to the problem was "better education" of lawn crews for more "courteous" use of their equipment, a claim for which the lobbyists could offer no real-world evidence (since none exists).

The whole transcript is available now, so you can judge for yourself. Over the two weeks after the hearing, until a July 16 deadline, the Council's record stayed open for supplemental statements. A large number of those arrived, and they'll be presented, in indexed form, in the next few days on this site.

An 18-Second Lesson in the Difference Between Gas-Powered and Battery-Powered Leaf Blowers

For the D.C. City Council's July 2 hearing on a bill to phase-out noisy, dirty gas-powered leaf blowers, and phase in quiet, clean battery-powered models, a well-known research group called Arup conducted original sound-measurement experiments. 

The purpose of the tests was to see whether there was any real difference in the acoustic properties of noise from different kinds of machines. (More of about the hearing, on July 2, here; a full transcript of the proceedings is here; the testimony of Arup's witness, acoustics expert Chris Pollock, is here.)

As it turned out, indeed there is a difference. As Pollock emphasized, the main contrast is in low-frequency sound energy, which gas-powered machines produce at much more intense levels than battery-powered machines.

"Low-frequency" noise seems as if it might be more benign than a high-frequency whine, but in fact it's a much more serious public health and public nuisance problem. That is because low-frequency waves travel much further than high-frequency ones, and penetrate walls, doors, and windows. Thus two leaf blowers with the "same" loudness rating, say of 75 decibels, have vastly different noise footprints, with the gas-powered one affecting a much greater area. At the hearing, Dr. Jamie Banks, of Quiet Communities, illustrated the difference with this chart. The two blowers shown at the top are battery-powered; the two at the bottom, gas-powered. (In their response at the hearing, the two industry lobbyists said that noise and nuisance problems could be solved by training lawn crews in "considerate" use of the equipment. See for yourself.)

But here's an even simpler way to grasp the difference: just listen to the 18-second sound clip below, from the Arup experiments. It's of two blowers that officially have the "same" loudness rating, measured at the same distance.

The first ten seconds are a battery-powered machine, with a distinctive high whine -- but a sound that falls off very rapidly with distance. If this machine were running outside a building, you might not hear it inside.

The second is of a gas-powered machine.

See if you can notice the difference! 

Noise as 'the New Second-Hand Smoke'

Some of the public-health challenges of this era are familiar: diabetes, obesity, and of course the opioid epidemic.

Some are less publicized and just beginning to break into public awareness. Among them is what the CDC (Centers for Disease Control) has noted as an incipient epidemic of hearing loss, at much younger ages than had previously been observed. As the CDC said in a report this spring (emphasis added):

“Noise is damaging hearing before anyone notices or diagnoses it,” said Anne Schuchat, the CDC's acting director. “Because of that, the start of hearing loss is underrecognized.”

The study revealed that 19 percent of people between the ages of 20 and 29 had some hearing loss, a finding that Schuchat called alarming....

Hearing damage results from a combination of volume and the length of the exposure. One minute of hearing a 120-decibel siren can damage hearing, the CDC said. So can two hours of exposure to a 90-decibel leaf blower. 

Now the Pew Trusts have followed up with a report on the increasing toll causes by hearing loss, and the dawning awareness that this is a public-health challenge akin to the second-hand smoke phenomenon of a generation ago. The report is called "Seeking a Quiet Place in a Nation of Noise," and is worth reading in full, here. Some samples:

Noise doesn’t just affect hearing, noise activists say; it can cost your health. A study by the University of Michigan showed a link to cardiovascular disease and heart attacks, according to [Rick] Neitzel, who conducted the study.

“The consensus is that if we can keep noise below 70 decibels on average, that would eliminate hearing loss,” Neitzel said. “But the problem is that if noise is more than 50 decibels, there’s an increased risk of heart attack and hypertension,” he said. “Noise at 70 decibels is not safe.”

And:

Leaf blowers are another noise flashpoint.

Hundreds of cities have leaf blower regulations, but they are difficult to enforce. Regulation has been prevalent in California, Arizona, Hawaii, Illinois, New York and Massachusetts, according to Quiet Communities, a nonprofit that advocates for noise control.

State lawmakers in Hawaii have considered a ban on gas blowers. And cities like Washington, D.C., have been considering a ban for several years, but not passed one.

As chronicled on this site, Washington D.C. is, at last, indeed moving toward action on this front. Stay tuned for updates. 

The Big Picture: 'America's Lawn Obsession,' via Freakonomics

The main theme of the news and analyses on this site is that the modern lawn-care practices should, can, and inevitably will shift away from today's hyper-polluting, obsolescent, dangerous and dirty gas-powered equipment. Better alternatives are at hand, and are appearing in improved versions continually.

Another perspective is to reconsider current highly mechanized landscaping practices more fundamentally. Questions of this sort lead some householders to rely on rakes rather than machinery, and lead others to wonder about the modern American assumption that houses should be surrounded with manicured lawns.

The valuable Noise and the City blog has featured a Freakonomics broadcast from 2017 that asks directly, "How Stupid is Our Obsession With Lawns?" It's fascinating and worth listening to. An embedded player is below.

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WSJ: Big Battery Boost Is on the Horizon

Wall Street Journal headline, March 17, 2018.

The limiting factor in the usability and popularity of clean, electric-powered leaf blowers is the same as the limiting factor in the cost and range of Teslas and other electric cars, or of a new generation of battery-powered airplanes, or even of the spread of solar and wind power systems that need batteries to store power when it's sunny or wind, to use when it is dark or calm.

That factor is the performance and cost of batteries. Through the past decade, innovation (driven mainly by the mobile-phone and other consumer-electronics industry) has made batteries ever cheaper, ever lighter, and ever longer-duration. Now a Wall Street Journal story says that a significant step up is at hand.

The entire story by Christopher Mims is worth reading. Some highlights:

The batteries that power our modern world—from phones to drones to electric cars—will soon experience something not heard of in years: Their capacity to store electricity will jump by double-digit percentages, according to researchers, developers and manufacturers.

The next wave of batteries, long in the pipeline, is ready for commercialization. This will mean, among other things, phones with 10% to 30% more battery life, or phones with the same battery life but faster and lighter or with brighter screens.... As this technology becomes widespread, makers of electric vehicles [and lawn equipment] and home storage batteries will be able to knock thousands of dollars off their prices over the next five to 10 years.

The technical advance, carefully spelled out in the story, involves a move from graphite to silicon as a main component in the battery. Brief summary:

Typically, anodes in lithium-ion batteries are made of graphite, which is carbon in a crystalline form. While graphite anodes hold a substantial number of lithium ions, researchers have long known a different material, silicon, can hold 25 times as many.

For more, please see Mims's article. The big picture, once again, is that the dirty, noisy gas-powered equipment found on many lawns is a rare remnant of very old technology. What is rushing to replace it is part of a sweeping new material-science revolution in power storage. 

The 41 D.C. Neighborhoods (and Counting) That Have Supported Mary Cheh's Bill

Here is the list of neighborhoods across the District of Columbia whose elected representatives, on Advisory Neighborhood Commissions, have supported action on Council Member Mary Cheh's bill to speed the inevitable phase-out of hyper-polluting, obsolete, noisy gas-powered leaf blowers in the District. The neighborhoods are listed alphabetically, followed by their respective ANC numbers.

Congratulations and thanks to these visionary citizen representatives. 

1. American University (3D)
2. American University Park (3E) 
3. Berkley (3D)
4. Bloomingdale (5E)
5. Brookland (5B)
6. Capitol Hill (6B, 6C)
7. Carrollsburg (6D)
8. Cathedral Heights (3B)
9. Columbia Heights (4C)
10. Crestwood (4C)
11. Downtown (2F)
12. Eckington (5E)
13. Edgewood (5E)
14. Fort McNair (6D)
15. Foxhall (3D)
16. Friendship Heights (3E)
17. Glenwood (5E)
18. Glover Park (3B)
19. Kalorama (2D)
20. Kent (3D)
21. Logan Circle (2F)
22. Michigan Park (5B)
23. Navy Yard (6D)
24. Near Northeast (6C)
25. Near Southwest-Southeast (6D)
26. New Mexico-Cathedral (3D)
27. NoMa (6C)
28. North Michigan Park (5B)
29. Palisades (3D)
30. Petworth (4C)
31. Queen’s Chapel (5B)
32. Rhode Island Avenue (5B)
33. Shaw (2F)
34. Sheridan (2D)
35. 16th Street Heights (4C)
36. Spring Valley (3D)
37. Tenleytown (3E)
38. Truxton Circle (5E)
39. Waterfront (6D)
40. Wesley Heights (3D)
41. Woodridge (5B)

We'll update this list as more results come in.

To read more about this issue, and to consider adding your support to the thousand-plus people who have already signed a petition asking the D.C. Council to act, please visit the link below.

And Then There Were Ten: Local ANCs in Washington Supporting Mary Cheh's Bill

As previous installments -- especially here, here, and here -- have recounted, one by one Advisory Neighborhood Commissions in Washington D.C. have endorsed a bill to speed the change away from hyper-polluting, obsolete, dangerous gas-powered leaf blowers and similar equipment, and toward quiet, cleaner electric equipment.

Now a tenth ANC, number 3E, has voted to support the measure, which is proposed by D.C. Council member Mary Cheh. This means that one quarter of all the ANCs in the district, a very significant proportion for an effort like this, have taken the trouble (and paid the attention) to support this bill.

The next step is for Council Chair Phil Mendelson to hold hearings on the measure. A petition urging him to do so has attracted well over 1,000 signatures. Feel free to check it out here or through the link below.

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Here is the text of a resolution that another of the ANCs, number 5B, used in recommending Mary Cheh's measure.

Support at the Local Level Keeps Growing in Washington D.C.

Some quick background: This preceding item explained the two-year effort to have the nation's capital join the growing number of cities that are accelerating an inevitable shift, away from hyper-polluting, noisy, and dangerous gas-powered lawn equipment, and to modern clean and quieter models. This item described the legislation that Washington D.C. Council member Mary Cheh has introduced toward that end. And this item quoted the statements that a growing number of Advisory Neighborhood Commissions (ANCs) -- the branch of D.C. city government closest to the citizens, and reporting up to the City Council -- have made in endorsing the measure.

Since then, two more ANCs have voted to support action on Mary Cheh's bill. (For D.C. residents, these are ANCs 2F and 6C.)  So as of now, nine ANCs from five different wards of the city have voted--usually by lopsided positive margins--to support City Council hearings and action on Mary Cheh's bill, with several more ANC meetings to come soon. This is broad and significant support, which (to be honest) few people would have foreseen when this effort began back in the fall of 2015. Thanks to these visionary Advisory Neighborhood Commissioners, and to the QCDC members who have taken the lead in making the case to them. 

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Below you will find a Change.Org petition asking D.C. Council Chair Phil Mendelson to hold hearings on Mary Cheh's bill, in accord with the wishes of a growing number of ANCs. For an idea of similar efforts across the country, see this link -- and to read and sign the D.C. petition, which so far is nearing 1,000 supporters, see the link below.

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Update: The Change.Org petition linked above, asking Council Chair Phil Mendelson to hold hearings on a bill that a majority of Council members support and that growing numbers of ANC organizations have endorsed, has now crossed the 1,000-signatures mark. Please read it and add yours.

As a look through Change.Org's search function shows, many other communities are acting toward the same end. For instance, the first two items on the search list are:

'Leaves in Piles': A Poem

Stewart Burke, of the Washington D.C. area, has reflected on the modern predicament involving leaves and leaf-related equipment. He sends this explanation, and the resulting poem:

My condo office would cite me if I were to unfurl on my terrace a banner bearing the word noise, but thinks nothing about sending out the cleaning crews to blow leaves around the front drive without hearing protection. Ensconced as I am in the Rosslyn hi-rise condo equivalent of a Daoist sage’s rude hut, the issue of leaf blowers has become a passionate one for me, so much so that I was moved to write a poem:

Congrats and thanks Mr. Burke, herewith the 2018 poet laureate of the Quiet Clean movement.. 

D.C. Local Politics at a Decision Point (and Welcome to Atlantic Readers)

The item below is cross-posted from The Atlantic's site, where over the years Atlantic writer and QCDC member James Fallows had been introducing the story of the effort to phase out gas-powered leaf blowers and other equipment in Washington D.C. and around the country. 

We welcome Atlantic readers, hope you'll explore the site, and invite you to sign this Change.Org petition to request hearings on a bill that already enjoys broad support in the District.

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By James Fallows

Back in the fall of 2015, in the midst of travels around the country in which my wife, Deb, and I saw countless examples of citizens taking responsibility for changing their own communities, I mentioned a specific way Deb and I intended to apply the lessons of what we’d seen. As the first item in this series explained:

Over the past two years, Deb and I have been increasingly impressed by the importance, vitality, difficulty, and effectiveness of local-level activism in the cities we’ve visited across the United States. We’ve interviewed and written about the people who are committed to changing the texture of life—and have!—in Sioux Falls, or in Fresno or San Bernardino, or in Greenville, or in Eastport or Duluth or Columbus or Allentown or Burlington or Redlands or Pittsburgh.

They have done it. What about us?

What about the place where our children were born and where they finished high school, where we own a house and have lived for more years than anyplace else: Washington D.C.? Don’t we have an obligation to keep pitching in too? The District is the site of national / international struggles but also of intense local involvement. Over the years, our local involvement has been mainly with our immediate neighborhood and with youth sports leagues and the public schools, when our children were there.

One way in which we got involved was to join a group of neighbors trying to bring the nation’s capital up to speed with a growing number of other cities, in phasing out use of the (obviously) noisy, but also surprisingly dangerous, polluting, environmentally destructive, and technologically outdated piece of machinery known as the gas-powered leaf blower. Dozens of cities have already done this. A recent example is Key Biscayne, Florida, which mandated a shift to cleaner, quieter battery-powered equipment — and gave lawn-maintenance companies a whole 180 days to comply.

So over the past two years, or the parts of it when we’ve been in D.C,. we have met with our neighbors and friends for the unglamorous but weirdly satisfying slog of trying to change minds and organize support for local legislative action. Specifically, we’ve been urging the District Council to consider and pass a bill proposed by Council Member Mary Cheh, which would phase out gas-powered leaf blowers over the next few years. (You can read its text here.)

The enjoyable part has been regular meetings of our little group of allies, over muffins and coffee at one or another of our houses. It has also meant: talking with experts on air pollution, noise pollution, lawn maintenance, engine-design, regulation-enforcement, and other issues, from all around the country. Plus preparing testimony for City Council appearances. Calling council members one by one, and going downtown to for discussions with them (or first, usually, their staffers). Arranging and attending demos of new clean-tech lawn equipment. Raising money to support a web site and informational videos. Going to local citizen forums to explain the issue. Learning about the regulatory thickets that apply in most U.S. states but are different in California (which has more leeway, under federal clean-air regulations, to set its own standards) and Washington D.C. (which has less leeway on almost everything than “real” states do, as attested by our “Taxation Without Representation” D.C. license plates.)

The most important work of all, done mainly by one of our colleagues and described more fully below, has been going from one Advisory Neighborhood Commission to the next, explaining the arguments, and getting commissioners to vote in favor of changing the District’s policy.

This item, the last in the series in this space, is an account of what has happened since then, what comes next, and where further online updates can be found.

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Mainly this is a story of the effect of hyper-local-level civic engagement—even in a place like the District, which is not fully in control of its own affairs (because of the Congress’s continued control over local governance), which is the center of so many other consequential issues, which has so many divisions within it. What has happened so far falls into these categories:

Local support and involvement. The closest-to-the-citizen unit of government in the District is its set of Advisory Neighborhood Commissions, which answer directly to local people and which report up to the City Council. Our effort began with an 8-1 vote in favor of the phase-out from our own ANC. Over the past year our members (mainly one heroic member) have gone from ANC to ANC, made the presentation, and gotten support, usually by lopsided positive votes. Six ANCs have endorsed the measure, with more continuing to vote. You can read samples of their statements of support here.

Environmental data. The underlying technical problem with gas-powered leaf blowers is that they rely on a technology so obsolete, so polluting, and so primitive that it has been outlawed or phased out in most other uses. These two stroke engines burn a slurry of gasoline and oil – and burn it so inefficiently that some 30% of the fuel is sprayed straight out as polluting aerosols. The fuel that is burned is done so crudely that one little leaf blower can be vastly more polluting than a fleet of modern cars – as cars and trucks have gotten cleaner, and this old tech has stayed the same. One famous study found that running a leaf blower for half an hour was, in terms of certain kinds of pollution, the equivalent of driving a truck for thousands of miles. Some old-tech industry lobbyists complain about these studies, but anyone who recalls tobacco industry denials will recognize the tone of the discussion. And the major manufacturers are moving ahead to promoting their cleaner battery-powered models.

Public health data. The CDC says there is an incipient epidemic of hearing damage, for which nuisance noise like this is a major effect. Acoustic studies have documented the unusually penetrating qualities of very loud and low frequency noise from leaf blowers. Other studies have identified the carcinogenic, asthma-inducing, and other disease-causing elements in the engine emissions and the clouds of fine particulates the blowers produce. These effects extend across neighborhoods, but of course are most intensely concentrated, in much of the country, on hired lawn crews. The members of these teams are usually low-wage, often foreign-born, often not English-speaking. Overall they are much more vulnerable than the people who are paying them, and are far from guaranteed to have good health coverage a decade or so in the future when the pulmonary and auditory effects of their work take their toll.

Technological progress. All the major manufacturers know where technology and policy are leading them, and are featuring new battery-powered models. The revolution in price-and-performance for batteries that is being driven by Elon Musk’s Tesla and many other firms is affecting this business as well.

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As a cumulative effect of trends in all these areas, the most dramatic change is probably in the battlefield of ideas. Several years ago, the standard response to even talking about leaf-blowers was, “Seriously? This is what you’re concerned about?” Now more and more media mentions treat the acceptance of leaf-blowers as an inexplicably unsafe, dirty, socially destructive artifact of modern life.

For instance, from the Wall Street Journal:

From The Week magazine:

From the Washington Post:

From the NYT:

Finally from NJ.Com, the editorial board of the Newark Star-Ledger.

There is much more about the policy and legislative background of the bill, which you can read in detail here. The political reality now is this:

ANC’s from across the District have approved the proposed anti-leafblower bill. A majority of members of the City Council have either co-sponsored the measure or indicated their support of it. But before anything can finally happen, the relevant committee of the City Council must hold hearings. And, by decision of City Council chair Phil Mendelson, the committee that will hold hearings and consider the bill is the “Committee of the Whole” – the entire City Council.

City Council Chair Phil Mendelson (DC City Council)

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Will Chair Mendelson, up for a re-election run this year, agree to schedule hearings – on a measure that most Council members support, and that many ANCs have already endorsed? So far more than 900 people have signed a Change.Org petition requesting that he do so.

Because the Atlantic’s site is meant for analysis and description rather than advocacy, I’ve said nothing more in this space about the D.C. campaign since we got serious about it in the fall of 2016. Instead our group has posted updates—on environmental and public-health research, technical improvements, legislative developments—in the News section at our own independent site, called QuietCleanDC.com. I invite you to visit that site for further news. It’s been a rewarding stage of engagement, which is bound to have a positive outcome – soon, I hope.

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