The Clean Air Act aims to protect public health and welfare from air pollution, established largely due to growing environmental concerns in the 1970s. It regulates six common pollutants, known as criteria pollutants, which include particulate matter, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead, all of which can have serious health and environmental impacts. The EPA monitors these pollutants through air quality standards and tracking methods, although many areas still experience unhealthy air conditions.

1. Understanding Clean Air Act &Understanding Clean Air Act &
Common PollutantsCommon Pollutants
Vivek Shetty
shvi1987@gmail.com
262-497-1362
https://www.linkedin.com/in/vivekshetty1987

2. Clean Air ActClean Air Act
About: Congress designed the Clean Air Act to protect public
heath and welfare from different types of air pollution caused by
a diverse array of pollution sources.
Basic structure formation – 1970
Dense, visible smog in many of nation’s cities and Industrial
centers helped to prompt passage of the 1970 legislation at the
height of national environmental movement.
Revisions – 1977 & 1990
Revisions were designed to improve the effectiveness of the
legislation and to target newly recognized air pollution problems
like acid rains and damage to stratospheric ozone layer

3. Clean Air HistoryClean Air History
 1955 - Air Pollution Control Act Provided Money for Pollution
Research
 1963 - Clean Air Act Directed Development of Methods for
Monitoring and Controlling Air Pollution
 1967 - Air Quality Act Initiated Enforcement and Source
Inspections
 1970 - Clean Air Act and National Environmental Policy Act
(NEPA)
 1971 - EPA Established by (NEPA).
 1977 - Clean Air Act Amended.
 1990 - Clean Air Act Further Amended.
1973 - 1994: EPA Focus was On-Highway Applications
1994 to Present: EPA Focus is Non-Road Mobile &
Stationary Applications

4. Control of common pollutantsControl of common pollutants
 To protect public health and welfare nationwide, the
Clean Air Act requires EPA to establish national ambient
air quality standards for certain common and widespread
pollutants based on the latest science.
 EPA has set air quality standards for six common "criteria
pollutants"

5. What are Criteria Pollutants?What are Criteria Pollutants?
 EPA calls these pollutants "criteria" air pollutants because it regulates them
by developing human health-based and/or environmentally-based criteria
(science-based guidelines) for setting permissible levels.
◦ The set of limits based on human health is called primary standards
◦ Another set of limits intended to prevent environmental and property damage is
called secondary standards
 Criteria Pollutants are commonly found air pollutants that are found all over US
◦ Particle pollution (PM) (often referred to as particulate matter)
◦ Ground-level ozone
◦ Carbon monoxide (CO)
◦ Sulfur oxides (SO2)
◦ Nitrogen oxides (SO2)
◦ Lead (Pb)
 These pollutants can harm your health and the environment, and cause property damage
 Of the six pollutants, particle pollution and ground-level ozone are the most widespread
health threats

6. Details about Criteria PollutantsDetails about Criteria Pollutants
 Particulate matter (PM): a complex mixture of extremely small particles and liquid
droplets. Particle pollution is made up of a number of components, including acids (such as
nitrates and sulfates), organic chemicals, metals, and soil or dust particles
◦ Effect: The size of particles is directly linked to their potential for causing health problems.
EPA is concerned about particles that are 10 micrometers in diameter or smaller because
those are the particles that generally pass through the throat and nose and enter the lungs.
Once inhaled, these particles can affect the heart and lungs and cause serious health effects.
EPA groups particle pollution into two categories:
 "Inhalable coarse particles," such as those found near roadways and dusty
industries, are larger than 2.5 micrometers and smaller than 10 micrometers in
diameter.
 "Fine particles," such as those found in smoke and haze, are 2.5 micrometers in
diameter and smaller. These particles can be directly emitted from sources such as
forest fires, or they can form when gases emitted from power plants, industries and
automobiles react in the air.
 Carbon monoxide (CO): is a colorless, odorless gas emitted from combustion processes.
Nationally and, particularly in urban areas, the majority of CO emissions to ambient air come
from mobile sources.
◦ Effects: CO can cause harmful health effects by reducing oxygen delivery to the body's
organs (like the heart and brain) and tissues. At extremely high levels, CO can cause
death.

7. Details about Criteria PollutantsDetails about Criteria Pollutants
 Ozone: Ground level or "bad" ozone is not emitted directly into the air, but is created by
chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC)
in the presence of sunlight.
◦ Source: Emissions from industrial facilities and electric utilities, motor vehicle exhaust,
gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC.
◦ Effects: Breathing ozone can trigger a variety of health problems, particularly for children,
the elderly, and people of all ages who have lung diseases such as asthma. Ground level
ozone can also have harmful effects on sensitive vegetation and ecosystems.
◦ Ground Level Ozone makes it hard to breath
 Sulfur Oxides (SO2): is one of a group of highly reactive gasses known as “oxides of sulfur.”
◦ Source: The largest sources of SO2 emissions are from fossil fuel combustion at power
plants (73%) and other industrial facilities (20%). Smaller sources of SO2 emissions include
industrial processes such as extracting metal from ore, and the burning of high sulfur
containing fuels by locomotives, large ships, and non-road equipment.
◦ Effects: SO2 is linked with a number of adverse effects on the respiratory system.

8. Details about Criteria PollutantsDetails about Criteria Pollutants
 Nitrogen dioxide (NO2): is one of a group of highly reactive gasses known as "oxides of nitrogen," or
"nitrogen oxides (NOx)." Other nitrogen oxides include nitrous acid and nitric acid. EPA’s National
Ambient Air Quality Standard uses NO2 as the indicator for the larger group of nitrogen oxides.
◦ Source: NO2 forms quickly from emissions from cars, trucks and buses, power plants, and off-road
equipment.
◦ Effects: In addition to contributing to the formation of ground-level ozone, and fine particle
pollution, NO2 is linked with a number of adverse effects on the respiratory system.
 Lead (Pb): is a metal found naturally in the environment as well as in manufactured products.
◦ Source: The major sources of lead emissions have historically been from fuels in on-road motor
vehicles (such as cars and trucks) and industrial sources. As a result of EPA's regulatory efforts to
remove lead from on-road motor vehicle gasoline, emissions of lead from the transportation sector
dramatically declined by 95 percent between 1980 and 1999, and levels of lead in the air decreased by
94 percent between 1980 and 1999. Today, the highest levels of lead in air are usually found near
lead smelters.
◦ The major sources of lead emissions to the air today are ore and metals processing and piston-engine
aircraft operating on leaded aviation gasoline.
◦ Effects: Once taken into the body, lead distributes throughout the body in the blood and is
accumulated in the bones. Depending on the level of exposure, lead can adversely affect the nervous
system, kidney function, immune system, reproductive and developmental systems and the
cardiovascular system. Lead exposure also affects the oxygen carrying capacity of the blood. The
lead effects most commonly encountered in current populations are neurological effects in children
and cardiovascular effects (e.g., high blood pressure and heart disease) in adults. Infants and young
children are especially sensitive to even low levels of lead, which may contribute to behavioral

9. How these pollutants are trackedHow these pollutants are tracked
 EPA tracks two kinds of air pollution trends:
◦ Air concentrations based on actual measurements of pollutant
concentrations in the ambient (outside) air at selected
monitoring sites throughout the country,
◦ Emissions based on engineering estimates of the total tons of
pollutants released into the air each year.
Note: Despite the progress made in the last 30 years, millions of
people live in counties with monitor data showing unhealthy air
for one or more of the six common air pollutants.

10. Thank You!Thank You!
Sources:
http://www.epa.gov/air/caa/requirements.html
http://narsa.org/

11. What’s Next?What’s Next?
EPA’s Tiered approach to handle Criteria
Pollutants for Non-Road Mobile Diesel
(NRMD)