This Astounding Stat Shows How Staggering The California Wildfires Have Been

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In Northern California's Butte County, firefighters continued to battle what has become the deadliest wildfire in California's history on Friday as the number of people reported missing doubled to more than 600. But the effects of the Camp Fire are also being felt well outside of Butte County. Smoke from the Camp Fire hangs heavy in the air in the San Francisco Bay Area, nearly 200 miles south of the fire, causing a number of residents to don face respirator masks. In fact, wildfire smoke brought the air quality in Northern California down to rank worst in the world, according to air monitoring groups.

According to PurpleAir, an air quality monitoring app that maps data from the Federal Environmental Protection Agency's Air Quality Index (AQI) scale, air quality in cities throughout California's Bay Area ranked worst in the world, prompting school closures and warnings to limit time outdoors as pollutants reached hazardous levels. As of Friday morning, San Francisco had an air quality index rating ranging from the high 200s to 313 in different parts of the city.

Across the Bay, in Oakland and Hayward, the air quality hovered in the mid to high 200s. In the South Bay, it was recorded as ranging from 160 to 245. And in the East Bay's Contra Costa County, the air quality index ranged from 197 in Dublin to 345 in Lafayette to 356 in parts of Walnut Creek.

According to AirNow, "good" air quality — meaning, the air is "satisfactory and poses little or no health risk" — is ranked as ranging from zero to 50 on the air quality index. "Moderate" air quality falls between 51 to 100, while air reported to be "unhealthy for sensitive groups" ranks between 101 to 150. "Unhealthy" air, which AirNow notes means "everyone may begin to experience health effects," falls between 151 and 200 on the air quality index.

Air rated as being "very unhealthy," meaning more serious health effects may be felt by everyone, ranks from 201 to 300, while "hazardous" air is anything ranking above 300. According to AirNow, "very unhealthy" air often triggers a health alert while "hazardous" air, which has been reported in various parts of Northern California, triggers warnings of emergency conditions. As a result of the air quality warnings, schools and universities across the Bay Area were closed Friday, according to The Mercury News.

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Earlier this week, California Public Health officials warned those living or working in areas where smoke is present to reduce their exposure to the outdoors and to wear a respirator mask if they must go outside. But not all masks are created equally. According to ABC News, California Public Health officials have recommended using masks labeled with "N95," "P95," "R95," or with an even higher filter rating of "N100," "P100," and "R100" to filter out smoke particles.

Unfortunately, meteorologists don't think Northern California is likely to get a respite from the bad air quality until late next week. A potential rain storm is then expected to sweep the smoke away, The San Francisco Chronicle has reported.