As County Fire rages, what's the risk from breathing? Here's air quality info for the region

Smoke obscured the skies and ash dusted windshields in the Bay Area and Sacramento regions the past two mornings as the 60,000-acre County Fire continued to grow, miles away in Yolo County.

The fire and its byproducts were jeopardizing air quality and public to varying extents depending on location as of Monday morning.

The Yolo-Solano Air Quality Management District issued a Smoke Alert extending from Monday through Saturday, including the Fourth of July. Winds are expected to carry the most smoke into Esparto, Vacaville, Winters, Davis and Woodland, but all parts of Yolo County and northeast Solano County are expected to be affected.

As the week progresses, winds are predicted to "continue to transport smoke from the fire into the region," according to the district.

Ozone levels rose to unsafe levels by Monday afternoon in Sacramento County for at-risk groups such as young children, pregnant women, older people and individuals with respiratory conditions like asthma or heart disease.

The smoke is certainly worsening ozone production, but these levels are not unusual for this time of year, said Thomas Hall, spokesperson for the Sacramento Metropolitan Air Quality District.

Air quality in the Sacramento area was worst in Elk Grove and Vacaville, according to a 2:30 p.m. tweet by the Sacramento Metropolitan Air Quality District.

Although smoke may have been visible in Sacramento County by Monday morning, it had not descended to breathing altitude and was not adversely affecting air quality in the county, Hall said.

When it comes to smoke detection, "we really encourage folks to use their nose," Hall said. Residents who smell smoke are advised to head indoors.

In general, residents should avoid outdoor physical activity, close windows and doors that might let in smoke, turn off all wood-burning appliances and turn on their air conditioners, according to the Yolo-Solano Air Quality Management District.

If outside, residents should consider donning face masks with high efficiency particulate air (HEPA) filters or an N-95 mask, as regular dust masks don't filter out wildfire air pollution safely, the American Lung Association advises. These warnings are especially pertinent for the aforementioned at-risk groups.

All air quality monitoring stations in the Bay Area were reporting good or moderate AQI levels of particulate matter (PM) and ozone as of 8 a.m. Monday, which means that even groups predisposed to sensitivity should be safe to spend time outside, according to the Bay Area Air Quality Management District. Hall said he expects the Delta breeze to send smoke eastward and away from the Bay Area as the week progresses.

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The predicted wind direction and its effect on the County Fire for July 2. Bay Area Air Quality Management District

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The predicted wind direction and its effect on the County Fire for July 3 & 4. Bay Area Air Quality Management District

Along with wildfire air quality concerns, Californians should also weigh the air pollution risks posed by fireworks, the San Joaquin Valley Air Pollution Control District said in a news release.

Fireworks release hazardous particles such as soot, ash and metals into the atmosphere, and air monitors in the San Joaquin Valley have accordingly detected unsafe spikes in PM concentrations every July 4 evening, the district said.

As such, the city of Winters in Yolo County had canceled its July 3 fireworks show as of Monday morning, according to the city's website. The city does not appear to have scheduled a fireworks show on July 4.

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On July 4, 2017, in the city of Visalia, particulate matter levels in the air exceeded the "Heavily Polluted" benchmark around 10 p.m., rendering the air unsafe. San Joaquin Valley Air Pollution Control District

In general, smoke may look entirely gaseous, but it contains miniscule chunks of PM that pose health risks ranging from headaches to heart problems.

Combined with cloudless weather and hot temperatures, smoke concentration increases the production of ozone. The molecule is an essential component of the Earth's upper atmosphere, but it's unhealthy and synonymous with smog when present in altitudes closer to sea level.

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