Breakup is in the air, and so is all the dust that lies dormant throughout the winter, waiting for the day when warmer weather allows it to be released. Gravel, sand and dirt get pulverized on roads and highways into dust particles that fly through the air come springtime.
Of particular concern for air quality and public health experts are tiny particles that comprise just 10 microns of space or less — one-tenth the width of a human hair. These minute dust devils, collectively called particulate matter 10, or PM10 for short, can become lodged in human lung tissue.
Every year, the spike in PM10 that occurs during breakup correlates with an increase in hospital visits for asthma-related problems and upper respiratory infections, according to one state and two municipal studies on the problem locally.
“Typically, it starts about now, the end of March, and the very worst goes through mid-April, maybe on bad years to the end of April,” said Steve Morris, an air quality program manager for the Municipality of Anchorage. His program monitors PM10 concentrations at several sites, including the one in Eagle River on the roof of the Park Gate Building near Old Glenn Highway and Easy Street.
The monitoring program, which has been in existence since 1985 when the Environmental Protection Agency (EPA) instituted safety guidelines for PM10, has consistently shown a peak in PM10 during springtime for all areas where samples are collected and a smaller peak during the fall.
All three studies on PM10 in the Anchorage area have shown measurable health impacts at levels well below the EPA safety standard of 150 micrograms per cubic meter of air in any given 24-hour period.
The higher the PM10 concentration, the more marked are the effects on public health. A study entitled Particulate Area Pollution and Repertory Disease in Anchorage, Alaska, which was co-authored by physician and researcher Mary Ellen Gordian in 1996, identified a 1 to 3 percent increase in asthma-related outpatient visits and a 3 to 6 percent increase in upper respiratory infection outpatient visits for every increase of 10 micrograms of PM10 per cubic meter of air.
"The cleaner the air, the healthier the people," said Gordian. "They've not found a threshold level that seems safe. Obviously we can't eliminate all dust pollution, but all dust pollution is associated with increases in respiratory problems." Gordian said she thinks PM10 pollution aggravates, but doesn't cause, illnesses such as asthma and upper respiratory infections.
"We see (the) highest dust levels on big roads,” Morris said. “Old Glenn Highway is similar to heavily-traveled roads in Anchorage.”
Unlike some other urban areas, where PM10 sources are primarily from industrial pollution, over 90 percent of PM10 comes from dirt from roads.
Gordian said it's a good idea to avoid exercising outdoors when PM10 levels are high.
"Also, PM10 is associated with roadways, but it drops off very quickly away from roadways," Gordian said. "People who are exercising should do so away from the roadway."
Eagle River exceeded EPA safety standards for PM10 on several occasions in the 1980s, when much of its transportation infrastructure consisted of unpaved roads. Paving and surfacing of roads in 1988 led to a marked decline in Eagle River's PM10 pollution. Measurements for the pollutant in Eagle River have remained comparable to those in Anchorage since then, with the overall trend for PM10 staying about the same. Annual highs in Eagle River from 1995 to 2005 ranged from 59 to 90 micrograms of PM10 per cubic meter of air, with the exception of a windstorm in 2003 that drove PM10 concentrations up to 590 micrograms per cubic meter of air.
According to a report conducted by the Midwest Research Institute in 1999 on local PM10 measurement and control, the municipality took several measures to put a damper on particulate pollution starting in 1996. It halved the volume of traction sand applied to roads, lowered contract specifications for the sand it uses to contain less than 1 percent fine particles (down from 7 percent in the late 90s) and increased the use of magnesium chloride de-icer in its winter battle against slick roads.
Morris said the air quality program is working with street maintenance to reduce PM10 pollution in the Anchorage area. This spring, the municipality is putting magnesium chloride to the test against spring dust. In addition to being a commonly used de-icer, the salty substance is used in many areas nationally to contain road dust. Morris said the city will experiment with different solution strengths and frequencies of application on approximately 18 miles of road in Anchorage, including a section of Muldoon Road, to determine the most effective application.
The city will also try out a new street sweeper that does a better job of controlling dust, Morris said.
Further, Eagle River will soon be the home of a new PM10 monitor. The one currently in use at the Park Gate Building requires manual installation and retrieval of its specialized filters to obtain data for the PM10 concentration over a 24-hour period, a process completed once every six days at the Eagle River location.
Once installed, the new monitoring equipment will take hourly measurements and feed the data to a computer, which will then be posted on the Web for public access. Residents will be able to go to the air quality Web site and check reported PM10 levels measured at the Park Gate Building hourly. Morris estimates the new monitoring system for Eagle River will be in place by this summer.
For more information on the municipality's air quality program, go to http://www.ci.anchorage.ak.us/healthesd/air.cfm.
Reach the reporter at news@alaskastar.com.
