Our View: Sweeping streets is more than cosmetic
February 28, 2015
The noise made by city street sweepers in the wee hours.
Sweeping city streets is essential to keeping Steamboat on the healthy side of air pollution regs.
We can empathize with downtown residents who are losing sleep over the noise made by the city of Steamboat Springs' pre-dawn street-sweeping operations this winter. However, we believe City Council's plans to exempt street sweeping from the city noise ordinance, as it has already for emergency vehicles and snow plows, is a necessary step.
In fact, we are aware that city officials are obligated, under the terms of agreements with both the Colorado Department of Public Health and Environment (CDPHE) and the federal Environmental Protection Agency, to sweep the streets once they have dried following snow events. That effort is made to reduce a kind of air pollution referred to as "PM-10." The abbreviation refers to tiny particulates suspended in the air that measure 10-microns or less – roughly the diameter of a human hair.
Routt County Environmental Health Director Mike Zopf said Friday that the city renewed its commitment to both the state and federal agencies within the last five years and that agreement is recorded in the Federal Register. His office continues to collect filters from four different air samplers seven days a week and mails them to the CDPHE for testing.
"The city can't ignore it, and the street sweeping has made a huge difference," Zopf said. "I have to take my hat off to them because they have done a great job and it yields public health benefits, no doubt about it."
And the most effective time of day to sweep the streets is when the fewest vehicles are present.
Steamboat was compelled to do something about its air pollution problem after it violated federal air quality standards on three occasions spread between 1989 and 1990. A pallor of wood smoke, which sometimes hung over the valley floor when a strong inversion layer existed, contributed to the problem. And so did the crushed scoria cinders that have long been used here to give traction to icy winter roads.
Zopf told Steamboat Today in 2006 that Steamboat's air has not experienced a violation since 1996 and air quality is well within standards today, thanks to a commitment to street sweeping and an aggressive policy undertaken years ago to drastically reduce the number of wood-burning appliances in the city.
The street sweeping is necessitated in part by the contribution to PM-10 air pollution made by scoria, the readily available volcanic cinders that are spread on our streets to keep motorists safe during the long Steamboat winters.
Scoria is plentiful in South Routt and its sharp edges provide traction even in periods of daily snow. However, it breaks down fairly quickly under the weight of passing vehicles, and the cinders are pulverized into fine dust particles that fit under the PM-10 standard. The scoria dust tends to settle on the shoulder of the road where the effect of passing cars and trucks cause it to become airborne. And the virtual lid that a winter inversion clamps onto the valley floor can trap scoria dust and particles from wood smoke close to the ground.
Zopf said when the state and federal government studied Steamboat's air pollution problem in the 1990s, they analyzed filter samples to find the chemical signature of the pollutants in our air.
Street sand — scoria — was the number-one cause, he said, with fireplaces and wood-burning stoves ranking second. However, restaurant grills, the exhaust from railroad locomotives and airplanes, and on certain days, the Hayden Power plant, were all turning up.
Wood smoke has been drastically reduced here by converting vacation condominiums to cleaner burning gas fireplaces and prohibiting wood-burning stoves and fireplaces in new homes.
Even with wood smoke less of a problem, Zopf said it's important to keep up the street sweeping, because a period of strong temperature inversions could take Steamboat to the edge of a violation.
Unfortunately for the residents of Steamboat who are troubled by the noise, the wee hours, when fewer cars are parked on the street in downtown and traffic is minimal, represent the most effective time of day for the city to live up to its agreement with state and federal agencies.