Aspen air: clean but warm |

Aspen air: clean but warm

Aspen Times writer

Aspen’s latest air quality report offers good and bad news: Particulate pollution is relatively low, but air temperatures are on the rise.

Particulate pollution known as PM-10 – particulate matter smaller than 10 millionths of a meter in size – is the air pollutant monitored in Aspen. The resort was once in violation of federal health standards for PM-10, but has since implemented several measures that successfully lowered PM-10 levels.

In 2003, Aspen’s highest PM-10 reading was 70 millionths of a gram in a cubic meter of air. The federal standard is 150 – not to be exceeded more than once per year. Aspen’s highest reading in 2002 was 59.

In the previous decade, three years produced PM-10 highs that were lower than 2003’s worst day for PM-10, while seven years saw higher readings than the worst day in 2003, according to the city’s Environmental Health Department.

Discounted last year was a reading of 102 on Oct. 30. The reading was the result of large wildfires in the western United States rather than pollution produced locally, according to Lee Cassin, the city’s environmental health director.

The more worrisome news in Aspen’s air quality report, Cassin contends, is the increasing trend toward longer summers and shorter winters. The resort’s summers have increased an average of four and a half days per decade since record keeping began in 1949. Most of the gain has come in the last 20 years, when summers have gotten longer at a rate of 13 days per decade, according to Cassin.

In Aspen and worldwide, spring is coming earlier each year and fall is arriving later. The number of below-zero days in Aspen was also lower than usual. Scientists believe that the recent rise in the Earth’s surface temperature is caused mostly by human activities, not natural variations in climate, according to Cassin.

Aspen is doing its part by generating 57 percent of its electricity from renewable wind and hydropower that do not contribute to global warming, she noted.

The air quality report can be viewed on the city’s Web site at and free copies are available from the Environmental Health Department on the second floor of City Hall.

Aspen’s summers have increased an average of four and a half days per decade since record keeping began in 1949.


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