AIR QUALITY INDICATORS

The EPA uses six "criteria pollutants" as indicators of air quality and has

set standards for each of these under the NAAQS. When an area does not

meet these standards, it is designated as a nonattainment area and must

develop and implement a plan for attainment. The six criteria pollutants

are ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, particulate

matter, and lead.

OZONE

Ozone, an odorless, colorless gas, made up of three atoms of oxygen, is

the major component in smog. There is "good" ozone and "bad" ozone

depending on its location. The "good" ozone is in the upper atmosphere

and provides a shield from harmful ultraviolet radiation. 
(This ozone shield is being seriously threatened 
by various global warming processes.) 
The "bad" ozone is at ground level where it poses a significant threat to human

health by damaging lung tissue, reducing lung function, and sensitizing

the lung to other irritants, causing a range of symptoms including coughing,

sneezing, pulmonary congestion, and chest pain.

Ozone is created by a complex set of Volitile Organic compounds (VOCs)

and oxides of nitrogen in the presence of sunlight. These chemical reactions

are affected by sunlight and heat, resulting in greater production of

ozone in warmer seasons. Volatile organic compounds are emitted by a

wide range of polluting sources, including dry cleaners, cars, chemical

manufacturers, paint shops, and many others.

CARBON MONOXIDE

Carbon monoxide is a colorless, odorless, and poisonous gas produced

during the burning of fossil fuels (coal and oil). The vast majority of carbon

monoxide is produced by automobiles. However, incinerators, woodburning

stoves, and other industrial sources also contribute. Carbon

monoxide binds with human hemoglobin in a way that precludes the binding

of oxygen. This results in anoxia. The most sensitive populations to

carbon monoxide poisoning are people with cardiovascular diseases and

chronic obstructive pulmonary disease (COPD) and smokers. There is some

evidence that carbon monoxide exposure may actually accelerate atherosclerosis.

Flu-like symptoms such as headache and fatigue are associated

with low-level exposures. Neurologic manifestations include changes in

auditory and visual perception, psychomotor function, and dexterity.

SULFUR DIOXIDE

Sulfur dioxide is a gas that is formed during the combustion of fossil fuels,

during an array of industrial processes, and during the production of energy

from coal, oil, and biomass. It is a major contributor to acid rain. Sulfur

dioxide is also associated with a constellation of health effects, including

respiratory illness, alterations in pulmonary function, aggravation of existing

cardiovascular diseases, and exacerbations in asthma.

AIR QUALITY THREATS

In agricultural areas, where aerial pesticide applications are made, pesticides

may drift, volatilize, and disperse downwind. Ground water, surface

water, soil, and food may become contaminated. The indoor air is also

likely to become contaminated with the pesticide drift. General population

exposure has been well documented, with residues of pesticides and

metabolites found in blood, urine, breast milk, fat tissue, and other tissues.

Health practitioners should factor such potential exposures into their patient

and community assessments.

Incinerators pose a threat to air quality, releasing a range of pollutants

depending on the waste stream composition. They will typically include

the metals (mercury, lead, arsenic, cadmium, chromium, manganese, nickel,

antimony, selenium, zinc, and vanadium); PCBs, furans, polycyclic aromatic

hydrocarbons, and acid gases and oxides of nitrogen, sulfur, and carbon.

Proximity to incinerators is associated with increased local soil lead levels.

A particular concern arising from our poor air quality is global warming,

a change in our global climate resulting from the changes in industrial

and agricultural processes that, in turn, have changed the gases in our

atmosphere. So-called greenhouse gases are those gases (both naturally

occurring and man-made) that are capable of adsorbing heat in the atmosphere.

The naturally occurring greenhouse gases are water vapor, carbon

dioxide, methane, nitrous oxide, and ozone. Man-made contributions to

these gases include carbon dioxide, methane, nitrous oxide, and several

very powerful greenhouse gases: hydrofluorocarbons (MFCs), perfluorocarbons

(PFCs), and sulfur hexafluoride (SF6), which are generated by

industrial processes.

The resulting climate changes occurring from the extraordinary addition

of man-made, greenhouse gases are rising temperatures (.5-1 degree

since the nineteenth century) and a rise in the sea level (4-8 inches in the

last century). Alterations in forests, crop yield, and water supplies are predicted.

There is nothing that will reverse this trajectory in the near future,

and only a global strategy will succeed in addressing the long-term trends.

Because of the inevitability of the warming processes and the potential

public health ramifications of global warming, health professionals should

be educating themselves and weighing in on this very important issue.