This is the Denver Metro Air Pollution Forecast effective 4PM on Friday, 11/20/2009:

No Advisories are in effect for the seven-county Denver-Boulder metropolitan area until at least 4 PM Saturday, 11/21/2009. Good or moderate air quality conditions are expected.

Good mixing of the atmosphere is expected to keep air quality in the good-to-moderate range Friday evening and on Saturday.

For statewide conditions, forecasts and advisories, visit:
http://www.colorado.gov/airquality/colorado_summary.aspx

A poorly maintained vehicle pollutes more than a well maintained one. If you must drive, properly maintain your vehicle. We'll all breathe easier!

At 4PM (MST), Friday, 11/20/2009 the highest AQI value was 40 for Particulate < 10 micrometers which indicates Good air quality.

Friday, November 20, 2009, 3:00 PM: FRONT RANGE AIR QUALITY FORECAST: Ozone concentrations are expected to be in the Good category on Friday and Saturday. Fine particulates are expected to be in the Good Range on Friday and Saturday. Carbon Monoxide levels are expected to remain in the Good category on Friday and Saturday. Moderate visibility is forecast for Saturday. COLORADO SMOKE OUTLOOK: There could be areas of light to moderate smoke in the immediate vicinity of controlled burns and small wildfires. For satellite analysis of smoke over the U.S., visit: http://www.firedetect.noaa.gov/viewer.htm IF VISIBILITY IS LESS THAN 5 MILES IN SMOKE IN YOUR NEIGHBORHOOD DUE TO A WILDFIRE OR CONTROLLED BURN, SMOKE HAS REACHED LEVELS THAT ARE UNHEALTHY. If smoke is thick or becomes thick in your neighborhood you may want to remain indoors. This is especially true for those with heart disease, respiratory illnesses, the very young, and the elderly. Consider limiting outdoor activity when moderate to heavy smoke is present. Consider relocating temporarily if smoke is present indoors and is making you ill.

The Winter High Pollution Advisory Program is coordinated by the Air Pollution Control Division of the Colorado Department of Public Health and Environment.

Winter season air pollution forecasts are issued daily from October 31 through March 31 at 4 p.m. When conditions warrant, forecasts will include information about Action Days and subsequent residential burning restrictions.

An Action Day for fine particulates, carbon monoxide or ozone indicates that either current air quality is unhealthy or conditions are expected to worsen later in the day or on the next day. Action Days for air pollutants generally indicate that air quality will be in either the Unhealthy or Unhealthy-for-Sensitive-Groups categories according to the Air Quality Index. Action Days trigger mandatory residential burning restrictions (see residential burning below), voluntary driving reductions, and public health recommendations.

An Action Day for Visibility alone indicates that the Visibility Standard Index for visual air quality is expected to be poor on the current or following day. An Action Day for Visibility will trigger mandatory residential burning restrictions and voluntary driving reductions for the seven-county Denver-Boulder metropolitan area only (see residential burning below).

When no advisories are issued, air quality is good or moderate and is expected to remain so during the effective period of the forecast. No restrictions are in place.

The VISIBILITY STANDARD INDEX reports the air's visual quality in the seven-county Denver-Boulder metropolitan area. The visibility standard is 0.076 per kilometer of atmospheric extinction, which means that 7.6 percent of the light in a kilometer of air is blocked. The level must exceed the standard based on a four-hour average for a violation to occur. On the Visibility Standard Index Scale, a value of 101 equates to the 0.076/km standard. Values between 0-50 are good, 51-100 moderate, 101-200 poor and 201-plus extremely poor.

The AIR QUALITY INDEX reports the daily level of air pollution on an hourly basis. The index reports the highest level of either carbon monoxide, fine particulates or ozone depending on which pollutant has the greatest hourly concentration. Values greater than 100 for carbon monoxide, fine particulates and ozone indicate exceedances of the pollutant's state and federal standards. Air Quality Index values between 0-50 are good, 51-100 moderate, 101-150 unhealthy for sensitive groups, 151-200 unhealthy, 201-300 very unhealthy, and over 300 hazardous.

RESIDENTIAL BURNING: During Action Days, mandatory residential burning restrictions generally apply to everyone in the entire seven-county Denver-Boulder metropolitan area below 7,000 feet. The restrictions will be enforced through local ordinances or a state regulation.

The state regulation applies to any community in the seven-county Denver-Boulder metropolitan area that did not have its own mandatory residential burning ordinance in effect on January 1, 1990. Under this regulation, the only exceptions to the residential burning restrictions are for residences above 7,000 feet in the seven-county Denver-Boulder metropolitan area; and those who use Colorado Phase III (Phase II EPA) certified woodburning stoves, Colorado approved pellet stoves, approved masonry heaters or those whose stoves or fireplaces are their primary source of heat. For more information on residential burning restrictions, call the Air Pollution Control Division at (303) 692-3100.
For more, go to: http://www.cdphe.state.co.us/ap/woodhome.html

For current air quality information and updates:
http://www.colorado.gov/airquality/advisory.aspx
http://www.colorado.gov/airquality/air_quality.aspx

About the Air Quality Index:
http://www.epa.gov/airnow/aqi_brochure_08-09.pdf