The symptoms are familiar
to all those who live in cities where the air is polluted:
aching lungs, wheezing, coughing, headache. Millions of residents
of the South Coast Basin (which includes Los Angeles, Orange,
and parts of San Bernardino and Riverside counties) breathe
dirty air some one-third the days of the year.
Ozone levels here, or what most refer to as
smog, are often twice the federal health standard. In 1995,
the standard was exceeded on 98 days at one or more Basin
locations, most frequently in the east San Gabriel Valley.
What does all of this polluted air do to the
body? The answer depends on the situation. How long a person
is exposed to pollution, the type and concentration, the place,
time and day, temperature, weather and more.
But one thing is certain: Smog is harmful to
your health.
Lungs are ozone's primary target. Studies on
animals show that ozone damages cells in the lung's airways,
causing inflammation and swelling. It also reduces the respiratory
system's ability to fight infection and remove foreign particles.
Ozone may pose a particular health threat to
those who already suffer from respiratory problems such as
asthma, emphysema and chronic bronchitis. About 10% of the
basin's approximately 14 million residents fit into this category.
Ozone may also pose a health threat to the young, elderly
and cardiovascular patients.
Ozone affects healthy people as well. In 1990,
the State Air Resources Board established a new health advisory
level in response to mounting evidence that smog affects healthy,
exercising adults at lower levels than previously believed.
Now, a health advisory is issued at .15 parts per million
(on the pollutant standards index) before a first stage smog
alert is called when ozone levels reach .20 ppm.
During a health advisory, everyone, including
healthy adults and children are advised to avoid prolonged,
vigorous outdoor exercise. Susceptible individuals, including
those with heart or lung disease, should avoid outdoor activities
until the advisory is cancelled.
Currently, the federal Environmental Protection
Agency is reviewing the adequacy of the federal health standard
for ozone and is considering tightening it.
Sources
of Smog
The sources of pollution include emissions from
on-road vehicles, non-road vehicles like planes, ships and
trains, industries, and even small businesses and households
where polluting products are used.
Ozone, an invisible gas, is not emitted directly
into the air, but forms when nitrogen oxides from fuel combustion
and volatile organic gases from evaporated petroleum products
react in the presence of sunshine. Ozone levels are highest
during the warm months when there is strong sunshine, high
temperatures and an inversion layer.
Nitrogen oxides are produced when fossil fuels
are burned in motor vehicles, power plants, furnaces and turbines.
Carbon monoxide is a by-product of combustion
that comes almost entirely from motor vehicles.
Fine particulates, which are emitted directly
as smoke and diesel soot and form in the air out of nitrogen
oxides and sulfur oxides, obscure visibility and can be inhaled
deep into the lungs.
Historical
Perspective
During the early years of World War II, Los
Angeles residents began to realize the consequences of an
increasingly industrialized area. Investigations began to
determine the cause of resident's eye irritation, crop damage,
severe reductions in visibility and the rapid deterioration
of rubber products. "Smog" became a familiar word
and everyday presence and scientists and medical personnel
began to look at its effects on public health.
In the mid-1950s, the state of California's
Public Health division started to step up its efforts to define
the problem of how and where smog forms, as well as address
the health concerns associated with exposure to smog. Ozone
levels were reaching peaks of .68 parts per million, more
than six times the federal health standard. Early efforts
to study the health effects of exposure to air pollution focused
on acute exposure episodes. Only recently have the long-term
exposure effects been addressed.
In a 1956 survey sent out by the Los Angeles
County Medical Association, physicians reported the following:
94.7% recognized the existence of a "smog
complex" involving eye irritation, irritation of the
respiratory tract, chest pains, cough, shortness of breath,
nausea and headache;
56.1% have "authenticated cases of individuals
leaving this area solely because of smog";
43.3% have recommended that patients move
from the area on account of the effect of smog on their
health;
86.7% have observed that patients with respiratory
diseases are more susceptible to smog than healthy adults;
68% believe that patients with cardiac diseases
are more susceptible to smog than healthy adults;
89.6% have noticed patients with allergies
are more susceptible to smog than healthy adults; and
81.3% believe that smog is a contributing
factor to cancer of the lungs and air passages.
Historic
Air Pollution Disasters
There have been several episodes in history
which illustrate the harmful effects of acute short-term exposure
to air pollution. Among those include:
Belgium's Meuse Valley
During a five-day fog in December 1930, 63 people died,
most of the deaths occurring on the fourth and fifth days.
Older persons with previously known diseases of the heart
or lungs accounted for the majority of fatalities. The signs
and symptoms were primarily those caused by a respiratory
irritant. They include chest pain, cough, shortness of breath
and irritation of the eyes. Sulfur dioxide gas is suspected
as the cause of the disaster.
Donora, Pennsylvania
Twenty people died and approximately 7,000 or 50% of the
population, experienced acute illness during the week of
Oct. 25, 1948, when temperature inversion and air stagnation
occurred. Persons of all ages became ill, but those over
55 were more severely affected. Those with previous heart
or respiratory disease, particularly bronchial asthma, suffered
most.
Symptoms were primarily respiratory and secondarily gastrointestinal,
and included cough, sore throat, chest constriction, shortness
of breath, eye irritation, nausea and vomiting. The onset
of the illness for most persons occurred on the evening
of the third day. Of the 20 who died, 14 had some known
heart or lung disease.
London, England
Three episodes during which heavy fogs and air pollution
were associated resulted in the death of nearly 5,000 people
- in 1948, 1952 and 1956.
The episode in December of 1952 alone, resulted in at least
3,000 deaths more than expected for that time of year. Although
the increase was present in every age group, the greatest
increase was in the age group of 45 years and over. More
than 80% of these deaths occurred among individuals with
known heart and respiratory disease.
During each of these incidents, comparable conditions
were present: limited air supplies as a result of low-lying
temperature inversions and faint winds, and a continuing heavy
output of air pollution from multiple sources.
Also, in none of the incidents was technology
sophisticated enough to properly monitor the air and diagnosis
of the specific causes of the illness and deaths were based
on limited evidence gathered after the disasters.
Health
Effects Studies
Since the 1950s, medical evidence chronicling
the effects of air pollution on the human body has continued
to mount. Here are summaries of some of the most recent medical
studies:
A 1989 study funded by AQMD and conducted
by Dr. Jane Hall of Cal State Fullerton found that meeting
federal clean air standards for ozone and fine particulates
in the South Coast region would provide $9.4 billion in
health-related benefits each year. The study found that
98% of the four-county basin's population of 13 million
is exposed to unhealthful air, with children especially
vulnerable. In addition, 1,600 people die prematurely as
a result of exposure to air pollution, according to the
study.
In 1991, as a follow up to the study, Hall
looked at how air quality impacts minority communities.
The study showed that minorities as a whole were shown to
be exposed more often to poor air quality since they tend
to live in more polluted air where housing is affordable.
African-Americans and Hispanics generally breathe the worst
air, partly because they tend to work in outdoor occupations.
Children are the focus of a study funded
by the California Air Resources Board that began in spring
1992 and will track 9,600 fourth, eighth and twelfth grade
students for up to 10 years to assess the potential health
damage from continued exposure to ozone, fine particulates
and atmospheric acidity. The lead scientist on the project
is Dr. John Peters of the University of Southern California.
David Abbey, Ph.D., of Loma Linda University,
studied a group of 6,340 Seventh Day Adventists living throughout
California (62% lived in the Basin). Results of the study
suggest a relationship between long term exposure to air
pollution and the development of specific chronic diseases.
Residents living in areas which exceeded state and federal
standards for suspended particulates on 42 days or more
per year had higher risks of respiratory diseases, including
a 33% greater bronchitis risk and 74% greater asthma risk.
In addition, women living in those high particulate areas
had a 37% higher risk of developing some form of cancer.
In 1987, Drs. Russell Sherwin and Valda Richters
of USC examined the health of 152 young people, between
the ages of 15 and 25, who died suddenly from accidents
or homicide. In lung autopsies of over 100 of the subjects,
slight lung airspace inflammation was found in 75% of the
group, with severe damage in 27%. In addition, all of the
youths examined had some degree of airway inflammation,
while 39% had severe illness in the bronchial glands and
29% had severe illness in their bronchial linings. Combined,
about 54% of the youths examined had at least one site of
severe illness. While no evidence has been found to deter-ine
the levels of smoking or other contributing factors that
could have affected their health, these youths appear to
have provided the first positive proof of health damage
from long-term exposure to poor air quality.
A study conducted by Dr. Roger Detels of
UCLA on chronic obstructive respiratory disease (CORD) looked
at residents of three Southern California areas (Long Beach,
Glendora and Lancaster) with different types and levels
of air pollution.
Participants aged 7 to 59 were questioned about lifestyle
habits and examined using lung function tests and histories
to record exposures to pollutants from workplaces and personal
habits, such as smoking.
Researchers followed those participants for more than five
years and found that the residents who lived in the more
polluted areas, Long Beach and Glendora, which experience
numerous days of unhealthful air, had more symptoms of respiratory
diseases such as bronchitis and asthma, while the residents
of Lancaster had measurably fewer symptoms of those illness.
Athletes may be relatively young, healthy,
physically fit and nonsmokers, but they may be among the
most vulnerable to the effects of inhaled ozone (and other
environmental pollutants), according to Dr. Henry Gong of
UCLA. Endurance studies suggest that athletic performance
may begin to suffer at the .12 ppm level of ozone (the federal
health standard), and is very likely at .20 ppm for most
athletes exercising heavily for one or more hours.
Fine particulate pollution -- even at levels
below the federal health standard -- can shorten lifespans
by two years, according to a 16-year study by Harvard University
researchers. In a study of 8,111 residents of six U.S. cities,
particle pollution was strongly associated with excess deaths
from lung cancer and heart disease -- even when other lifestyle
risks such as cigarette smoking were factored out.
The six cities studied -- Watertown, Mass., Harriman, Tenn.,
St. Louis and Steubenville, Ohio, Portage, Wis. and Topeka,
Kan. -- all have PM10 levels below the federal health standard.
In contrast, the South Coast Air Basin has some of the worst
PM10 pollution in the nation, nearly twice the federal health
standard.
A study by C. Arden Pope III, Ph.D., of Brigham
Young University found that particulate pollution reduces
the average life expectancy by one to three years in some
of the most polluted cities.
There have been many Environmental Protection
Agency studies looking at health effects. Some findings include:
A study of 10 adult men exposed to .12 ppm
ozone for 6.6 hours (including five hours of moderate exercise),
found that lung function decreased and respiratory symptoms
(coughing and breathing discomfort) increased over the more
than six hours of exposure.
In a study done on rats, continuous low level
exposure to ozone caused restrictive lung disease. Removal
of the rats from the ozone environment to one of clean,
filtered air appeared to reverse the disease state back
to normal. However, the study indicated that since people
do not breathe filtered air, ozone exceedances in numerous
cities would appear to promote pulmonary fibrosis.
In a field study of children during normal
activities at summer camp, lung function measurements were
taken before, during and after ozone levels reached above
.12 ppm on four days and .18 ppm on one day. Lung function
failed to return to its pre-episode level for many days
after the ozone episode had passed.
An acute exposure of humans to .40 ppm ozone
initiates biochemical changes in the lung resulting in the
production of components which contribute to inflammation
and acute lung damage and which can lead to long term effects
such as fibrosis. A study was initiated to determine if
prolonged exposure to low levels of ozone would produce
similar biochemical changes. Non-smoking males were randomly
exposed to filtered air and either .10 ppm or .08 ppm of
ozone for 6.6 hours with moderate exercise. The study concluded
that exposure of humans to low levels of ozone is sufficient
to cause an inflammatory reaction in the lungs.
Children
and Smog
A 1984 study conducted by Dr. Kay Kilburn, M.D.,
Professor of Medicine at USC showed that children raised in
the South Coast Air Basin suffer a 10% to 15% decrease in
lung function compared to children who grow up where the air
is less polluted.
The California Air Resources Board has concluded
that "since the lungs of children are not fully developed,
early damage to the respiratory tract could increase the risk
of respiratory disease in adult life."
Jane Hall's 1989 study on the health effects
of air pollution on residents of the South Coast Air Basin
estimated that school-age children, who represent only 20%
of the basin's population, experience more than 40% of the
symptoms associated with exposure to ozone.
Because of their physiology, children are much
more likely than adults to develop smog-related lung damage.
For their body size, children inhale several times more air
than adults, and they breathe faster, particularly during
strenuous physical activity. In addition, they spend more
time outdoors than any other segment of the population according
to the AQMD study.
Dr. Robert F. Phalen, Ph.D., professor of community
and environmental medicine and director of the Air Pollution
Health Effects Laboratory at the University of California,
Irvine, says that when children exercise, they tend to breathe
through their mouths.
According to Phalen, mouth-breathing bypasses
the natural filtering of air pollutants by the nose and allows
large volumes of polluted air to affect the more sensitive
areas of children's lungs which are still developing.
Studies show that children exposed to summer
ozone pollution year in, year out, have a greater susceptibility
to respiratory infections because chronic exposure to smog
impairs their immune system.
Research findings also suggest that, even if
children do not show symptoms while exercising in unhealthful
air, they are likely to suffer a loss in lung function compared
to youngsters who grow up where the air is less polluted.
Air Quality
Standards and Health
State and federal governments have set health
standards for pollutants, specifying levels beyond which the
air is unhealthful.
California's state standards for air pollutants
are more stringent than the federal government's. It is up
to each individual state to determine if they want to set
tougher standards.
Standards are set to provide an adequate margin
of safety in the protection of public health. Under the federal
Clean Air Act, EPA must base standards solely on health considerations
and not economics or technology.
The standards for pollutants in California include:
Ozone (one-hour average)
Federal = Not to exceed .12 ppm (parts per million) more
than one day per year. That means no more than .12 of a
volume of ozone per million volumes of air.
State = Not to equal or exceed .09 ppm
Carbon Monoxide
Federal = Not to exceed 35 ppm for one-hour average; 9.4
ppm for eight-hour average
State = Not to exceed 20 ppm for one-hour average; 9 ppm
for eight-hour average
PM 10 (particles 10 micrometers (millionths
of a meter) or less in diameter)
Federal = 150 micrograms per cubic meter of air for 24-hour
average (arithmetic mean); 50 micrograms per cubic meter
of air for annual average (arithmetic mean)
State = 50 micrograms per cubic meter of air for 24-hour
average; 30 micrograms per cubic meter of air for annual
average (geometric mean).
Nitrogen Dioxide
Federal = .52 ppm for one-hour average
State = .25 for one-hour average
Smog
episodes and what they mean
Various levels of smog episodes are reported
for the pollutant ozone. The declaration of a first, second
or third stage smog alert is based on the degree of health
risk. The protective actions help to reduce exposure to unhealthful
levels of ozone, but those who are especially sensitive should
contact their physician for more specific advice.
Generally, in the event of a smog alert, outdoor
activities should be scheduled for morning or early evening
hours to avoid the mid-day peak when ozone levels are at their
highest.
Some
Informational Telephone Numbers
Hourly updates on air pollution levels are available
to the public through the AQMD's toll-free, taped telephone
information service. AQMD's automated phone number to hear air quality reports by zip code is (800)
242-4022. Or go to AQMD's clickable map for hourly smog updates in Southern California.
Reprinted with permission.
First Published: late January 2003
Updated: April 2007
