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.

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