Outdoor Air Quality and Asthma
Outdoor air pollutants can be separated into two main groups, criteria
pollutants and hazardous air pollutants. The criteria pollutants include six compounds: ozone, particulate matter, sulfur dioxide, nitrogen dioxide, carbon monoxide and lead. Of these six compounds, ozone and particulate matter are most commonly linked with triggering asthma symptoms. At high levels, nitrogen dioxide and sulfur dioxide may
also be asthma triggers.
What Is Ozone Air Pollution?
Ground-level ozone, sometimes referred to as "smog," is created when a mixture
of air pollutants "bake" in the hot, summer sun. Ozone forms
in the atmosphere when sunlight and high temperatures act on
carbon-based chemicals known as volatile organic compounds (VOC's)
that combine with a group of air pollutants called oxides of
nitrogen or nitrogen oxides (NOx).
Typically, ozone levels are highest in Michigan during May through September
when weather conditions are right. When ozone levels are high
in Michigan the following factors are usually in place:
- Blue sky
- High temperatures (over 90°F)
NOx is a by-product of burning fuel in sources such as power plants,
steel mills and other factories, and vehicles. The U.S. Environmental
Protection Agency's (EPA's) 1997 National Air Quality Emissions
Trends Report states that about 23.6 million tons of NOx are
emitted each year, and the two largest sources are:
- 26% from coal-fired power plants across the nation (about 33%
from coal-fired plants in Michigan).
- 30% from on-road vehicles: cars, trucks, buses
Sources of VOC's include auto body shops, printers, gas stations, and
large industrial operations. The two largest sources are the transportation industry
(approx. 40%) and industrial process (approx. 31.2%)
What Are the Health Effects of Exposure to Ozone?
Although ozone is often impossible to see, smell or taste, it can have
a real impact on your health. Ozone acts as a powerful respiratory
irritant at levels often found in most of the nation's urban
areas during the ozone season. Ozone can aggravate asthma, causing
more asthma attacks, increased use of medication, more medical
treatment and more
visits to the hospital and emergency departments. Typical symptoms include:
- Shortness of breath: Ozone can constrict your breathing passages, making
it harder to breathe.
- Chest pain: Ozone reacts with lung tissue, often causing swelling
of the lungs and chest pain.
and coughing: High ozone levels can irritate your lungs and throat.
Based on evidence from research studies, ozone air pollution represents
a serious and widespread public health problem:
- In tests, healthy adults and children exercising strongly were found to have decreased
lung function after exposure to ozone even below the long-standing
federal 1-hour air quality standard of 0.12 parts per million
- Other studies of children and adults exercising outdoors suggest that lung function
decreases even at ozone levels equal to or below the newer
and more protective (8-hour at 0.08 ppm) health-based standard.
Although monitored by the state and federal regulatory
agencies, this new health-based standard is not currently
regulated by state agencies in the U.S.
- Research on the effects of longer exposures to ozone levels at, or
just below, the new health-based standard have found even
larger reductions in lung function, worsening inflammation
of the lung lining, and more frequent and severe respiratory
- Evidence also shows that higher ozone levels may even change lung function
for several days after an exposure. Recently, studies have
shown adverse health effects from long-term, repeated exposures
to high levels of ozone with a higher than expected loss of
lung function over time.
Who Is At Risk?
Check out State
of the Air
, at the American Lung Association website, to find out how Michigan is rated for outdoor air quality.
Three groups that have been identified who are at particular risk
from high ozone levels are:
In the 19 counties in Michigan where ozone pollution is the most
prevalent, the asthma prevalence population for children is
about 138,000 (73% of total children in Michigan with asthma)
and about 220,000 adults (about 62% of total adults in Michigan
The burden of asthma has been increasing over the past 20 years,
especially among children. Exposure to ozone pollution is especially
harmful to people with asthma, and about one-third of people
with asthma in Michigan are children.
Children are especially sensitive to the bad health effects of ozone
air pollution because they:
- Spend more time outdoors than adults
- Spend more time engaged in vigorous activity
- Have a higher breathing rate than adults, relative to their body weight
- Have narrower airways than adults
- Have more frequent respiratory infections
The "Out of Breath Report – Health Effects from Ozone in the Eastern
United States," Oct. 1999 shows the following ozone-related
bad health effects data for Michigan (mean cases April-October
- Cardiovascular hospital admissions: 670
- Respiratory hospital admissions: 2,100
- Total respiratory emergency department visits: 6,300
- Asthma emergency department visits: 660
- Minor respiratory symptoms: 3,600,000
- Asthma attacks: 280,000
What Changes are Needed in Michigan to Decrease Ozone Pollution?
The electric power industry is the largest industrial source of
smog-forming NOx emissions – about 33% of total NOx in Michigan.
More than a dozen old coal-burning power plants continue to
operate in Michigan despite outdated and poor pollution control
equipment for reducing NOx. As a nation, we still depend on
coal for more than half of our electricity needs.
Since ozone is moved easily over hundreds of miles from upwind regions,
other upwind states such as Indiana, Illinois and Wisconsin
will also have to reduce their NOx emissions greatly in order
for Michigan to get reductions of dangerous levels of summertime
ozone pollution. Therefore a regional solution to ozone transport
must be achieved, and federal legislation, currently being proposed
on Capitol Hill (e.g., S.556-The Clean Power Act), will be vital
to reach this goal.
What Can You Do to Help Reduce Unhealthy Ozone Levels in Michigan?
- Carpool, bus, walk or bicycle to work; find other ways to reduce
your car use. The fewer cars on our roads, the fewer pollutants in our air.
- Fill up your car's gas tank in the evening.
- Keep your car maintained to manufacturer's specifications and proper tire pressure.
- Postpone mowing your lawn on high ozone days; keep your grass cut
at a higher cut level (3 inches); consider purchasing an electric lawnmower when its time to replace the old one
- Spread the word: tell your family, friends and neighbors what they
can do to help and why. Consider your next automobile purchase to be a highly fuel- efficient hybrid and ultra-low
emission vehicle (ULEV) or consider purchasing an alternative
fueled vehicle (AFV) that uses 85% ethanol (E85) or natural gas.
Ground-level ozone is one of the toughest pollution problems we face. It
depends on weather conditions, many pollution sources and our
own actions. Even though we cannot dream of controlling the sun, wind and clouds
that contribute to the formation of ozone, we can make
sure our actions are helping to reduce ozone air pollution.
Check out this lawn
care tip card about keeping unhealthy ozone-forming pollutant levels down through smart lawn care.
Read this air quality information sheet with more specific information about AQI health messages and activity levels. This info is for parents, educators, coaches and caregivers of children and teens; those with cardio and/or pulmonary disease; and, adults who are sensitive to elevated concentrations of ozone and PM2.5 pollution levels.
Sign up for Enviro Flash a service that automatically delivers
air quality forecasts directly to subscribers. It provides "heads
up" information so people can adjust their daily activities
to match expected air quality conditions. Those enrolled get
only the information they select via email or cell
phone text messages.
What Is Particulate Matter Pollution?
Particulate matter – PM for short – is the familiar, often see-able pollutant
that fills our city air, settles on our windowsills, and irritates our eyes and noses. PM is:
- a mixture of many compounds and pollutants that usually come from combustion sources such
as power plants, industrial and residential smokestacks, fires,
mining, construction, natural sources, diesel trucks and buses,
other diesel vehicles and off-road diesel equipment.
- made up of many atmospheric materials including soot, ashes, windblown dirt, sand, soil dust, metals, and plant matter such as pollens.
- either given off directly from combustion sources like power plants, or is formed in the atmosphere through chemical reactions.
- sometimes referred to as PM2.5 (particulate matter smaller than 2.5 microns in diameter – less than one-hundredth of the width of a human hair) and
PM10 (particulate matter at 10 microns in diameter).
What Are the Health Effects of Exposure to Particulate Matter?
In the last few years, research studies have linked serious health
effects with PM at much lower levels than the current federal
standard allows for. PM2.5 is of gravest concern because the
particles are so tiny that they can be inhaled deeply into the
lungs, and can dodge the lungs' natural defenses. Numerous studies
over the years have linked PM2.5 to many health problems, from
increased asthma attacks to hospital visits to death.
- PM is linked with increased use of asthma medication in children, decline in respiratory
function, increased emergency room visits and hospitalization
for lung and heart problems. A number of studies have definitely
linked fine particle pollution with increased occurrence of
coughs and bronchitis, with especially severe effects in children
- PM is a dual threat to the asthmatic, whose airways are both
constricted and inflamed – PM makes both conditions worse. Research has shown that the levels of PM do not need
to be extremely high to cause these problems.
- PM shortens lives. Researchers estimate that as many as 60,000 people each year die too early
because of exposure to PM. The United States Environmental
Protection Agency (EPA) estimates that attainment of the new
health standard for fine particles alone could save 15,000
lives each year.
What are the Air Quality Standards for PM?
The EPA is currently reviewing the National Ambient Air Quality Standards (NAAQS) for fine
particulate matter (PM2.5). The Clean Air Act directs EPA to
conduct a rigorous review of the latest scientific evidence,
and to set standards at levels that will protect public health
with an adequate margin of safety. Standards are supposed to
protect the health of sensitive persons.
The NAAQS drive the nation's air pollution control programs. The
Clean Air Act requires the States and the EPA to come up with
strategies for reducing air pollution from sources that contribute
to air pollution in order to meet the air quality standards.
In July 2001, the EPA changed its air quality standards for
particulate matter and ozone. For the first time, the EPA set
specific standards for very fine particles, or PM2.5.
When the new fine particle standards were announced in 1997, the
President directed the EPA to complete its review of the PM
NAAQS within five years, by July 2002. At the same time, the EPA strengthened its PM research
program, together with other federal agencies, states, nonprofit
organizations, and industry research institutions. This schedule
would allow the Agency to consider the results of emerging scientific
research before new control programs took effect.
In 1999, the state of Michigan implemented a fine particulate (PM2.5)
monitoring system. This system is currently working, with 25
monitoring stations located throughout lower Michigan. The annual
PM2.5 standard is met when the 3-year average is less than or
equal to 15.0 micrograms per cubic meter (mg/m3). State monitoring
data can be reviewed at www.deqmiair.org/. The Department of Environmental Quality (DEQ) air page has more information about air quality standards and programs to keep Michigan's air clean.
Continuing Medical Education Credits (CMEs) are available online for many asthma topics, including ozone and particulate matter.