How you Control a day in Smog City 2
1.	Select "Save Smog City 2 from Ozone," "Save Smog City 2 from Particle
Pollution," or "Create Your Own Smog City 2 Experience."
2.	Set the weather control slider.
Daily weather conditions can significantly affect ozone and particle pollution
levels. Ozone levels are highest in the summer when high temperatures, calm
winds, and lots of sunshine prevail. In the real world we can't control the weather,
but in Smog City 2 you can experiment with how the weather affects pollution
levels by adjusting the controls.
Note: The temperature and Air Quality Index (AQI) are shown on the sign in the
city scape.
3. Set the emissions control sliders.
Particle pollution: Some particles are emitted directly from sources such as
construction sites, unpaved roads, fields, smokestacks, or fires. Others form when
chemicals such as sulfur dioxides (SO2) and nitrogen oxides (NOx) are emitted
into the atmosphere. NOx is produced from burning fuels, including gasoline and
diesel fuel. SO2 is produced from combustion of fuels containing sulfur, which
includes some coals. Particle pollution can occur year-round.
Ozone: Ground-level ozone is formed when volatile organic compounds
(VOCs) and NOx mix in sunlight. VOCs are emitted from products like gasoline,
industrial chemicals, dry cleaning solvents, paints, and household cleaners. NOx is
produced from burning fuels, including gasoline and diesel fuel. Ground-level
ozone is usually highest during the summer.
HINT: For a description of the items in the weather or emissions section, see
the information box.
4. Each time you set a control, check the Air Quality Index (AQI) and Total
Emissions.

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Pay special attention to the ozone levels, particle levels, time of day, and
health message. The multi-colored chart indicates the air quality at ground
level over time.
Note: The highest level of pollutant determines the AQI. In this example, the
AQI is 140, the highest ozone levels are 40 and the highest particle levels are
140.
Total Emissions
This chart shows the relative emissions from the energy, cars and trucks, off road
vehicles, consumer products and industry as you have selected them. The colors
of the bars in the graph match the pictures of the emission sources. These
categories create VOC, NOx, and SO2 emissions, which contribute to ground-level
ozone and particle pollution.
5.	See how population affects the Air Quality Index and Total Emissions.
Population growth affects emissions sources. For example, as the population increases,
emissions increase from additional use of energy, cars/trucks, consumer products and
industrial sources. Population is also linked to the use of wood-burning stoves and
fireplaces. When population increases and the outside air temperature falls below 50°F,
increased wood-burning causes more particle pollution.
6.	See how a dust storm or wildfire affects the Air Quality Index.
Random Events
Turn on/off events (fires and dust storms) that can affect the levels of particle
pollution in Smog City 2. Check the news crawler for details.
7.	Reset the controls
Reset
Returns the controls to their original settings.
Glossary
Weather:

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Clouds/Sky Cover
Sunlight accelerates the chemical reactions that form ozone. Clouds reduce
sunlight and slow ozone formation. Particle pollution forms more quickly when
there is moisture or cloud droplets in the air and increasing cloud cover speeds up
particle pollution formation. Cloud cover can be sunny, partly cloudy, or cloudy.
Inversion
A temperature inversion is a layer of warm air above the ground that traps particle
pollution and ground-level ozone below it. This "lid" prevents air from mixing
upward as it normally does. Smog City 2 has three temperature inversion settings:
low-altitude, high-altitude, or none.
Wind
Winds blow emissions from the pollution source to other areas. Calm winds cause
emission levels to build up, or increase. Wind speeds range from calm, light
breeze, breezy, or windy.
Temperature
Heat increases the chemical conversion of emissions to ozone and particle
pollution. Lower temperatures can enable gaseous emissions to convert into
particles. This control represents the daily maximum temperature and ranges from
30 to 110°F. Note: 60 and 70°F are not represented because the emissions at
those ranges are similar to 50 and 80°F, respectively.
Emissions:
Population
Population growth affects emissions sources. For example, as the population
increases, emissions increase from additional use of energy, cars/trucks, consumer
products and industrial sources. Population is also linked to the use of wood-
burning stoves and fireplaces. When population increases and the outside air
temperature falls below 50°F, increased wood-burning causes more particle
pollution. In Smog City 2, you can increase the population from near-zero to
about two million people.
Energy Sources
All forms of electricity production affect the environment. Most of the electricity
in the United States is generated from fossil fuels such as coal, natural gas and
oil. Emissions from burning of fossil fuels can lead to smog, acid rain, and haze.
Renewable energy like hydroelectric power, wind, and solar technologies produce
significantly fewer emissions than traditional power generation technologies.
Cars and Trucks
This category includes passenger vehicles (all sizes), large and medium trucks,
and motorcycles.

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Off Road
This category includes airplanes, trains, power boats, earth movers, tractors,
harvesters, forklifts, bulldozers, and backhoes.
Consumer Products
These products include hair spray, paints and paint thinner, charcoal lighter fluid,
glue or other adhesives, and gasoline that add VOCs to the environment.
Industry
Manufacturing facilities, power plants, oil refineries and distribution centers, and
food and agricultural processing are included in this category.
Air Quality and Health:
Air Quality Index (AQI)
The AQI is a color-coded index for reporting daily air quality. It tells you how
clean or polluted your air is, and what associated health effects might concern
you. The AQI focuses on health effects you may experience within a few hours or
days after breathing polluted air. The EPA calculates the AQI for five major air
pollutants as regulated by the federal Clean Air Act: ground-level ozone, particle
pollution (also known as particulate matter), carbon monoxide (CO), sulfur
dioxide (SO2), and nitrogen oxides (NOx). Ozone and particle pollution are the
most common air pollutants in the United States.
Ozone Levels
Ozone is the main ingredient of smog and presents a serious air quality problem.
Even at low levels, ozone can irritate your respiratory system causing coughing,
irritation in your throat, or a burning sensation in your airways. Ozone can
aggravate asthma and trigger asthma attacks.
Particle Levels
Airborne particles are the main ingredient of haze, smoke, and airborne dust.
Particle pollution can cause a number of serious health problems such as:
irritation of the eyes, nose and throat; coughing; phlegm; chest tightness; and
shortness of breath.

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