Changes focus on improving efficiency and delivering timely, transparent permit decisions.
Learn about Napa County - its climate, potential air pollution concerns, and current air quality. You can also view upcoming Air District events in Napa County and read about local efforts to improve air quality.
Napa County is nestled in a valley between the Maycamas Mountains in the west and the Vaca Mountains in the east. One Napa County representative sits on the Air District’s Board of Directors.
Changes focus on improving efficiency and delivering timely, transparent permit decisions.
The Air District has fined Chemtrade West US LLC $160,000 for air quality violations at its sulfuric acid manufacturing plant in Richmond, which is connected to the Chevron Richmond refinery. Chemtrade supplies various chemical products to industry, including sulfuric acid, which is a byproduct of refining crude oil.
The Air District is lifting an air quality advisory for wildfire smoke that was originally scheduled to last through tomorrow, Wednesday, August 27.
The Air District has announced a $13.3 million grant to the San Mateo County Transit District toward the installation of new high-capacity electric bus charging infrastructure at its San Carlos facility. This SamTrans project will help accelerate the transition of the SamTrans bus fleet to zero-emission technology and improve air quality in communities most affected by air pollution.
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The mountains bordering Napa Valley block much of the prevailing northwesterly winds throughout the year. Sunshine is plentiful in Napa County, and summertime can be very warm in the valley, particularly in the northern end. Winters are usually mild, with cool temperatures overnight and mild-to-moderate temperatures during the day. Wintertime temperatures tend to be slightly cooler in the northern end of the valley. Winds are generally calm throughout the county. Annual precipitation averages range from about 24 inches in low elevations to more than 40 inches in the mountains.
Interactive Air Monitoring Stations Map
Ozone and fine particle pollution, or PM2.5, are the major regional air pollutants of concern in the San Francisco Bay Area. Ozone is primarily a problem in the summer, and fine particle pollution in the winter.
In Napa County, ozone rarely exceeds health standards, but PM2.5 occasionally does reach unhealthy concentrations. There are multiple reasons for PM2.5 exceedances in Napa County. First, much of the county is wind-sheltered, which tends to trap PM2.5 within the Napa Valley.
Second, much of the area is well north of the moderating temperatures of San Pablo Bay and, as a result, Napa County experiences some of the coldest nights in the Bay Area. This leads to greater fireplace use and, in turn, higher PM2.5 levels. Finally, in the winter easterly winds often move fine-particle-laden air from the Central Valley to the Carquinez Strait and then into western Solano and southern Napa County.
Last Updated: 4/21/2017