Editor, Manteca Bulletin,

I think your column on lawn blower use in the San Joaquin Valley (Dennis Wyatt’s Oct. 25 column: “The answer, my friend, to better air quality is blowing in the wind”) described a pretty accurate pattern of use based on what I have observed in Fresno.

I ride a bike to and from work each day, often going home for lunch, for a total of 18 miles per day. I am in a position to observe a great deal of lawn blower use, and have gotten used to squinting and holding my breath.

The San Joaquin Valley Air Pollution Control District is hosting a conference on March 21 of 2012 on lawn care practices in the Valley and how the air pollution impacts can be reduced.  As part of the preparation, we have funded UCSF-Fresno to measure ultrafine particles or UFP (less than PM 0.1 rather than the current fine particulate size category of PM2.5) in Fresno from lawn care operations and other urban sources such as household wood smoke. 

We have found that lawn blowers and other two-stroke engines used in lawn care emit very high levels of UFP, which ultimately morph into PM2.5 sized particles over time and space. UFPs are of concern because a high fraction of the particles are deposited in deep in the lungs.  They are small but have large surface areas and are capable of avoiding the defense mechanisms of the lung.  And as hydrocarbon combustion products, they contain a high percentage of the organic carbon compounds, e.g. PAH, that are known to create pulmonary inflammation and sensitization of the immune system.

 The Valley is highly unlikely to ever meet the new standards for PM2.5 (2006 standards plus 2012 is likely to see a tougher annual daily standard) that have been set by the EPA unless we can get a handle on PM emissions from lawn care. 

David Lighthall
Health Science Advisor
San Joaquin Valley Air
Pollution Control District
Fresno