Planning for Particulate Standards

Particulate pollution can be a concern in Yolo-Solano, especially during the winter and during wildfires. The U.S. Environmental Protection Agency (EPA) separates harmful particulate pollution into two categories – coarse particulate and fine particulate. The District conducts air quality monitoring for both pollutants, but most of its planning efforts are focused on fine particulates.

Fine particulates are very small — it would take 25 of them lined up end to end to span the width of one human hair. Fine particulates can travel deep into your lungs, bypassing the body’s natural defenses. As a result, the lungs can be aggravated, especially for children, the elderly and those with respiratory ailments including asthma. Fine particulates have also been linked to heart disease.

Learn more about the health effects of particulate pollution »

Most of the time, fine particulate pollution levels in Yolo-Solano are in the healthy range. However, there are typically several days a year in which air quality is considered unhealthy for sensitive groups due to increased particulate pollution. In 2013, there were five days in which local air quality was unhealthy for sensitive groups because of particulate pollution. Four of those days were in the winter, and one was during a statewide wildfire episode.

Although the District generally does not experience unhealthy levels of particulates, the U.S. Environmental Protection Agency (EPA) has included the Yolo-Solano AQMD is included in the Sacramento Federal Non-Attainment Area for fine particulate pollution. The Clean Air Act requires areas not meeting health standards to develop strategies to achieve those standards by federal deadlines. The regional air districts work together closely to develop these plans and update them as required.

Regional air quality plans contain inventories of current and projected emissions from all relevant sources as well as proposed control measures intended to reduce these emissions in order to achieve healthy air quality levels. These control measures typically come in the form of new rules or revisions to acceptable emission limits for stationary sources.

Current Planning Effort

In order to show attainment of the 24-hour fine particulate standard, an area must demonstrate that it has met the standard during three consecutive years.  The Sacramento region was able to show that the standard had been achieved during the 2010-2012 period.  The Yolo-Solano AQMD and the other air districts of the region subsequently submitted a request to the U.S. EPA for a redesignation to attainment of the standard.  The districts also developed and submitted a “clean data finding” and a maintenance plan to EPA.  The clean data finding demonstrates that the standard has been met during a given three-year period, and the maintenance plan demonstrates how the standard will continue to be met in future years.

See the maintenance plan »

While achieving the 24-hour national standard for fine particulates is the primary focus for the Sacramento Region, the EPA has also adopted an annual standard for fine particulates.  This standard was tightened in 2012, but the Yolo-Solano AQMD and the rest of the Sacramento Region are consistently below it.