State officials have cancelled the air pollution health advisory that was in effect for the Twin Cities metro area for Wednesday and part of today.

Fine particles such as soot accumulated in the air, but winds have now moved the pollutants out of the area, said Rick Strassman, air monitoring supervisor for the Minnesota Pollution Control Agency. Strassman said the readings on the state's website still show air quality levels above 100, but that number is a 24-hour average and actual conditions are now in the safe range.

"This episode came and went pretty quick," he said. Air quality should remain good for the next several days and no more alerts are expected, Strassman said.

The Twin Cities metro area remains under an air pollution health advisory this afternoon. Relatively light winds and high mosture levels have allowed fine particles such as soot to accumulate, the Minnesota Pollution Control Agency warned.

Air quality reached the "unhealthy for sensitive groups" status yesterday afternoon. Under that condition, sensitive individuals with asthma, or heart or lung disease, are advised to reduce or postpone heavy exercize or exertion.

Alerts for sensitive individuals are issued when the air quality index exceeds 100. Since midnight the index for the Twin Cities has remained relatively constant between 114 and 118 and stood at 114 at 3 p.m.

If the particulates increase and the air quality index reaches 150 or more, the state would issue an additional warning that conditions are unhealthy for all. In that situation, everyone would be advised to reduce or postpone heavy exertion, indoors or outdoors.State officials issued an air pollution health advisory Wednesday for the Twin Cities metro area that extends through today.

Officials said weather conditions will probably improve air quality slightly on Friday.

• Affected areas: Twin Cities metro area.

• Who is affected: Sensitive individuals, including those with heart or lung disease, including asthma; those older than 50, and healthy adults and children engaged in vigorous exercise.

• Advice: Reduce or postpone heavy exertion, indoors or outdoors. Children can play outside for recess, but those who show symptoms of respiratory problems should be directed to a quieter activity.

• Cause: The small particles come from car exhaust, fireplaces, factories and other sources.

• Prevention: Reduce unnecessary driving, postpone using gasoline or diesel-powered small engines; cut back on use of wood stoves and fireplaces, if possible.

• Updates: Available at www.startribune.com/a1057.

TOM MEERSMAN

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