2010 March 26: CA Chico: More-rainy season washes particulate from sky, making Chico’s air cleaner.
GRIDLEY — Increased rain this winter cleaned the air, resulting in fewer days when a federal air pollution health standard was exceeded in Chico. While increasing awareness about the effect of residential wood burning contributed to the drop, rain got most of the credit in a report Butte County Air Quality Management District staff gave the district board Thursday.
"The worst air quality issues were when we didn’t have rain," air quality planner Gail Williams said.
"People are thinking about it more," she added. "We get five to 10 calls a week asking ‘can we burn?’" or seeking information on the issue.
But Williams pointed out Chico and the valley are surrounded by hills and prone to inversion layers that trap air close to the ground.
"Any emissions that are produced aren’t going to dissipate without a storm."
Data provided to the board showed two days in November when the federal health standard was exceeded in Chico and nine days in December.
Comparing the district’s pollution data for December with rainfall measurements at the Enterprise-Record’s weather station provides a clear correlation.
The health standard was exceeded six of the first nine days of the month, despite "Check Before You Light" advisories being issued four of those days.
That period was dry. When a series of storms began dropping rain on the 11th and continued on and off for 11 days, a two-week period of clearer air ensued.
The storms ended on Dec. 21, and by the 24th,
the standard had been exceeded again, and stayed high until about a third of an inch of rain fell on the 27th. There were no "exceedences" in January and February, and there was measurable precipitation at Enterprise-Record weather station 21 days in January and 14 days in February.
Williams presented the information during a report on the "Check Before You Light" program in Chico, which asked residents to refrain from lighting fireplaces or older woodstoves on days when poor air quality was forecast.
Wood smoke has been identified as a major component in so-called "small particulate" pollution that can build up to unhealthy levels when the air is still, and dry.
The pollution consists of microscopic bits of soot and other materials that can be inhaled deeply into the lungs and become lodged there.
The 11 days the health standard was exceeded is the lowest in the last nine years. From 2001-02 to 2006-07 the number of unhealthy days fluctuated from 25 to 40.
The "Don’t Light Tonight" and "Check Before You Light" programs were implemented in the Chico area the winter of 2005-06, and have been refined each year. In 2007-08, the number of days was down to 19, dipping to 18 the following year.
This winter, the district aims to improve its forecasting and educational efforts, and seek grants to help residents swap out woodstoves.
There was no mention of the voluntary "Check Before You Light" program, probably because the city of Chico is seeking a mandatory rule.
The city had asked that the matter be placed on the Board of Supervisor’s agenda for Tuesday’s meeting, as it is seeking the rule for the entire Chico sphere of influence, which includes unincorporated pockets.
However, Chico City Councilor Scott Gruendl said City Manager Dave Burkland told him the county administrative offices weren’t ready to pursue the matter yet.
The Air Quality District meeting, normally in Chico, was held in Gridley this month under a plan to rotate them among other cities in the county occasionally. Attendance was larger than is usual.
The Air Quality board and the Butte County Association of Governments will meet in Oroville in June and Paradise in September. The other meetings will be in Chico.
City Editor Steve Schoonover can be reached at 896-7750 or firstname.lastname@example.org.