An excessive concentration of dust in the air caused the Anchorage Department of Health and Human Services to issue a health advisory on Tuesday afternoon.
A rolling 24-hour average of particulates as measured at local monitoring sites went past 100 parts per million, which is considered unhealthy for sensitive groups. That would include "anyone with heart or respiratory ailments," like asthma, bronchitis or COPD, said Matt Stichick, an environmental engineer with the municipality's air quality program.
Conditions varied across the city, according to the Anchorage Air Quality Program webpage, from a reading of 25 -- "Good" -- in West Anchorage to 161 -- "Unhealthy" -- in Eagle River. Stichick said the average for the city was 110.
The problem stems from the weekend thaw and rains, Stichick said. "It took away the snow cover and washed a lot of the sediments onto the road surface." The light particles are then tossed into the air by traffic.
"There are similar conditions throughout Southcentral Alaska right now, with the same exposed ground," he said. "But what we're seeing here in town is coming off the roads."
Stichick said that in Anchorage the dust would be particularly bad along major thoroughfares and the high concentrations would continue "until we get some snow cover."
As long as present conditions prevail, the municipality advises people with sensitive heart and lung conditions to avoid dusty areas near major traffic thoroughfares, particularly during peak rush hours. Those with severe lung disease are advised to remain indoors.
The National Weather Service has predicted some snow on Wednesday with cold and dry weather to return at least until the weekend.
Air quality updates are available on the Municipal Air Quality Hotline, 343-4899. Hourly updates of air quality data in Anchorage, Eagle River and Mat-Su are available on the Alaska Air Monitoring Network at anchorageair.info.
Reach Mike Dunham at email@example.com or 257-4332.
By MIKE DUNHAM