‘Background’ Pollution

September 30, 2015

EmissionsConsidered ‘partly cloudy’ just after the noon hour here on California’s north coast with maybe some sunshine for later.
Rain forecast for the end of next week, but we’ll just wait and see…

In the meantime, we’re up to our necks in what’s called ‘background ozone,’ and it’s not good.
Via Capital Public Radio yesterday:

Northern California and Nevada may need to ask for exemptions to a federal air quality rule the EPA is expected to issue this week, according to a NASA-led study.
Ozone pollution — the main ingredient in smog — can be in a region but not originate from there or from human-produced sources.

The study indicates 77 percent of the total ozone up here is this ‘background’ stuff.

(Illustration found here).

And to deal with this problem, the EPA has proposed lowering the ozone standard from 75 parts per billion to between 65 and 70, which still might not be be enough for northern California because of our crazy wildfires that can push that ‘background ozone’ closer even to the proposed new limit.
The EPA is suppose to make its final ruling by Thursday.

The problem was spotted by NASA satellites:

Integrating Aura satellite data into the study increased the estimates of background ozone by an average of 2.4 parts per billion (ppb) over previous estimates, an amount that varied by 4 to 11 ppb over the two states.

Background ozone can be produced from natural local sources such as wildfires, and transported via winds from distant sources, such as the stratosphere or another region or country.
The NASA study found that, on average, background ozone sources generated about 48.3 ppb, or 77 percent, of the total ozone in the study region of California and Nevada.
The findings are particularly important in Northern California and Nevada, where wildfires and ozone transported to the region from abroad can cause background ozone to exceed 60 ppb.
The lowest background ozone levels were seen in Southern California, where topography helps trap local emissions.
“Our study shows background ozone plays a significant role in Western U.S. ozone levels under high-ozone conditions, and varies considerably by region, with higher values in many rural regions,” said Kevin Bowman, study co-author and principal investigator of Aura’s Tropospheric Emission Spectrometer (TES) instrument at JPL.
“Some regions in the West have high background ozone levels that leave less than 10 parts per billion for local ozone production under the EPA’s most aggressive proposed ground-level ozone standards.”

The Clean Air Act allows states to request an exemption to the ozone standard if they can show that the cause of an air-quality violation is due to ozone from outside the country or from natural causes.
To date, only Wyoming has been granted an exceptional event clearance by EPA due to high background ozone levels.

Nowadays it seems, weird-bad shit is turning up all the time…

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