Carbon
monoxide reduces the amount of oxygen that blood can carry, and
thus is hard on the heart. If a person has coronary artery disease,
even low levels of CO can be harmful. A study cited by the
Environmental Protection Agency in drawing up the federal standard
for CO noted that at a fairly low level "... there is evidence of
physiologic stress in patients with heart disease." Effects may be
present at even lower levels. (see Tables 6-2 and 6-3). CO
pollution is expressed in milligrams per cubic meter of air
(mg/m3) and the federal standard, at 10
mg/m3, is lower than levels at which physiological
effects may occur—at 35 mg/m3 or even 23
mg/m3. The effects of SO2, particulates, and
CO, the levels of concentration where the effects take place, and
the current federal standards are presented in Tables 6-2 and 6-3.
As is readily apparent, the standards, especially for particulates
and SO2, were not set much lower than the thresholds of
significant effects.
Hydrocarbons by themselves evidently do not
threaten health. But in the presence of sunlight they react with
nitrogen dioxide to form ozone, a main ingredient of photochemical
smog. Ozone irritates the eyes, but beyond that its effects have
not been established. However, some authorities cite dangers that
could lead to ill health. For example, Dr. Oscar J. Balchum of the
University of Southern California states:
It is
apparent that ozone results in sensory irritation, inflammation of
the airways and alveoli of the lungs, and reacts with cell membrane
and lung tissue components.... morphological and cellular
alterations... could be the inception of chronic processes,
resulting in persisting functional aberrations or even
disease.
In any case, control of ozone means control of hydrocarbons, and
the government has set standards.
Professor
Lyndon Babcock of the University of Illinois has estimated the
relative damage from air pollutants. Since some air pollutants
damage health more than others, there is little use in simply
adding together the various amounts. So Professor Babcock has
developed a way to measure air pollution's overall harm to health.
The method estimates roughly that effects of total suspended
particulates (TSP) are three times the effects of their emissions
(15 percent to 45 percent) and the effect of SO2 is
twice as large as its emission effect (15 percent to 30 percent).
On the other hand, CO, which makes up nearly 50 percent of total
pollution emissions, accounts for only 5 percent of total damage
according to Babcock. HC makes up about 15 percent of emissions and
causes around 5 percent of total effects.
These and
other effects of air pollution are expensive. Estimated costs for
1970 were $12.3 billion. Of that, damage to human health was $4.6
billion; reduced property values $5.8 billion; materials damage
$1.7 billion; and