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 (PM10) and fine particulate (PM2.5). 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.

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 (Yolo-Solano District boundary in red, SFNA boundary in yellow) 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 2009-2011 period.  The Yolo-Solano AQMD and the other air districts of the region subsequently prepared a PM2.5 maintenance plan and redesignation request.  The plan was submitted to ARB, but before it could be forwarded to EPA, there were some PM2.5 exceedances in late 2012.

On May 10, 2017, EPA found that the area attained the 2006 PM2.5 standard by the attainment date of December 31, 2015 (82FR21711). This finding was based on complete, quality-assured and certified PM2.5 monitoring data for 2013 – 2015.   The PM2.5 Maintenance Plan and Redesignation Request will be updated and submitted in the future based on the clean data finding made by the EPA.

The SFNA has been identified by the United States Environmental Protection Agency (EPA) as an area that is required to develop a mitigation plan to minimize the public exposure from PM2.5  emissions generated during wildfire events. Air districts in the SFNA-PM2.5 have jointly prepared the draft Wildfire Mitigation Plan for the Sacramento Federal Nonattainment Area for PM2.5 (Plan) as required by Title 40, Code of Federal Regulations, Part 51.930 (40 CFR 51.930)

This Plan outlines the actions each air district will take to notify the public and minimize the air quality impacts when emissions from wildfires increase PM2.5 concentrations in the region to a level where they exceed or are expected to exceed the 24-hour PM2.5 national ambient air quality standard.

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.