Most of the smoke blanketing northern Utah is not from the monster fire burning up much of Beaver and Millard counties. It's blowing in from other states, the chief of the Utah Department of Environmental Quality says.

"There's kind of a southeasterly flow that's pumping smoke from Idaho and the Northwest into northern Utah," said Rick Sprott, executive director of the DEQ. Smoke is blowing across the West from giant wildfires throughout the region.

The smoke causes coughing, headaches, red eyes and poor visibility for motorists and, presumably, pilots.

(Salt Lake International Airport officials did not immediately respond to several messages seeking information about visibility and aircraft delays.)

In addition, it can be dangerous to the health of sensitive people and might have long-term impacts for the healthy.

The smoke is so bad that it's triggered red alerts for several days. The alerts are to continue today, according to advisories issued Monday afternoon by the Utah Division of Air Quality. Unhealthy air quality was forecast for Cache, Salt Lake, Davis, Utah and Weber counties.

As Sprott noted, "You can even taste it in your mouth."

People with respiratory problems, plus the elderly and children, should "reduce prolonged or heavy exertion outside," according to state standards.

The Salt Lake Valley Health Department postponed its seasonal kick-off of the "Weigh Active and Healthy" event that had been scheduled for Monday at Liberty Park. Reasons cited by the health department were "extreme temperatures and poor air quality."

The weekly walks, about 1 mile long and starting at 6 p.m., were rescheduled to start Sept. 17. Other events are still slated for July 16 through Sept. 10 at sites throughout the county.

"We've really got two problems going here," Sprott explained.

They are:

• Ozone. "We have the traditional ozone issues and the ozone levels have been high." However, they're not as high as he would have expected, given the temperatures. The smoke may be reducing ultraviolet radiation reaching the lower atmosphere, and the ultraviolet is involved in forming ozone.

Still, he said on Monday, "Today we're starting to see some higher hourly values on ozone than we've seen here for a little while." And with grilling heat expected to continue for days, he believes, the Wasatch Front should have high ozone levels for several days.

For most of the Wasatch Front, ozone was in the "moderate" level Monday afternoon. But it reached a concentration considered "unhealthy for sensitive groups" in Ogden.