Why is this important?
Ozone in the upper atmosphere is necessary for our survival. Chemicals
from car exhaust and some industries can react with sunlight to produce
ground level ozone and smog, which are harmful to health. Severe
smog can cause acute symptoms, such as shortness of breath and throat
irritation. Even at lower levels, smog aggravates asthma and breathing
problems, and slows plant growth.
What is the measure?
The charts summarize progress made toward meeting state ambient
air quality standards.
How are we doing?
In May 2006, a new, more restrictive state 8-hour ozone standard
was adopted. This standard, set at 0.07 ppm (parts per million),
is intended to provide further protection for the public. Regulations
require that all air districts attain these new standards at the
earliest practical date.
However, the county is classified as "nonattainment" for
this standard because we emit only a small percentage of the total
emissions affecting our air quality. Pollutants generated and rising
from the Central Valley are a critical factor in the county’s
failure to meet the standards, and one over which we have no control.
The state recognizes this by designating Tuolumne County as an Overwhelming
Transport Area (see note at bottom of page), which does not require
any regulatory action being implemented.
Another challenge is balancing air quality goals with the need to
reduce wildfire risks through prescribed burning. Short-term exposure
to smoke from prescribed burns is one of the trade-offs for reducing
flammable forest fuels that could otherwise create extremely high
levels of pollution from wildfires.