Riding The Air Quality Rollercoaster In Roseville

Left: Here are the hourly concentrations of fine particulate matter (PM2.5, meaning particulate matter below 2.5 microns in diameter) at Roseville's PM2.5 monitor. The new national 24-hour average PM2.5 standard (35 ug/m3) is also indicated (the pre-2006 standard was 65 ug/m3).

Interestingly, there is a big, big peak of 180 ug/m3 on the evening of July 4th. What, oh what, could have been happening right at that moment that might generate smoke?


Courtesy of Bruce, here's what the Placer County air quality folks are recommending in their territory:

Air Quality Advisory for Mon., July 7, through Thurs., July 10, 2008

Placer County, CA July 7, 2008 – Widespread smoky conditions continue to affect Placer County from the valley floor to the Lake Tahoe area from fires inside and outside of the county. Average concentrations of fine particulates (PM2.5) continue to fluctuate throughout the day, with conditions ranging from hazardous to moderate.

With the continued smoke episode, Tom Christofk, Placer County Air Pollution Control Officer and Dr. Richard Burton, MD, Placer County’s Health Officer, are issuing this updated air quality advisory for July 7th through July 10th. The weather forecast for this week with the strong high pressure, very warm temperatures and little wind, combined with smoke, make for very stagnant conditions.

With cooler temperatures in the early morning, smoke tends to move down the western slope becoming more concentrated in foothill locations. In the afternoon hours and early evening, conditions appear to improve in the foothills as smoke rises into higher elevations, including the Lake Tahoe area.

The public is reminded to take common-sense precautions as Placer County will continue to be affected by very unhealthy or even hazardous air quality at times. If visibility is poor in your area, then you should strongly consider postponing outdoor activities until later in the day or when conditions improve.