Woodburning is relatively controlled, while wildfires are unpredictable and can quickly become uncontrolled if not contained quickly.
Since most of Napa County (including Napa itself) is too far north of the San Pablo Bay (located on the county’s southern border) to enjoy its moderating effect on temperatures, residents endure some of the coldest nights in the Bay Area.Winter months bring increased woodburning and winds that can cause air saturated with fine particle pollutants to move from the Central Valley to southern Napa County.Wildfires often cause a rapid rise in air pollution, which occurred in late summer 2020 when the Hennessey, Walbridge, and other wildfires triggered a Spare the Air alert.This can happen in Napa County due to several interdependent factors: Spare the Air days occur when PM2.5 particle concentrations rise to unhealthy levels. When pollution levels are high, follow recommend health advice to reduce your pollution exposure. To know what air quality in Napa Valley is, check this page regularly for data describing how healthy the air in Napa is at the present time and the Napa air quality index (AQI) for today as well as for the rest of this week. Napa County nonetheless experiences consistent fine particulate matter (PM2.5) pollution.įrom 2016 to 2018, the county averaged 10 days of air that was unhealthy for sensitive populations, 13 days when air was unhealthy for all, and two days when air was designated as “very unhealthy.”Īn increase in wildfire smoke during this period, caused by events such as the October 2017 Tubbs, Partrick, Nuns, and Atlas fires, was a major contributor to Napa County’s failing grade, along with woodburning and other sources. The data behind Napa County’s “B” grade for ground-level ozone (smog) showed that, in three years, the county averaged just two days of unhealthy air for sensitive populations, and no days with stronger health warnings. Historically, ground-level ozone formation has not been as prevalent in Napa County compared to other parts of the Bay Area closer to San Francisco, Oakland, and San Jose. To achieve an “A” rating, the county must have zero unhealthy air quality days.
3 The ALA assigns pollution grades by calculating a rolling three-year average of data for multiple types of pollution, then ranking air quality in the USA by compiling statistics for every county in the nation. The American Lung Association (ALA) rated the county a “B” for ozone and an “F” for 24-hour particle pollution. 1,2Īir pollution in Napa County receives mixed assessments.
Napa features a generally warm and temperate Mediterranean climate, with winters tending to be rainier than the summer months.
Napa County is part of a wider region known as Wine Country, named after its globally recognized wine exports. Napa, the seat of Napa County, is located in Northern California, approximately 48 miles north of San Francisco.