Transcript Urban Air Pollution

Urban Air Pollution &
Monitoring
5.7.1-5.7.3 & 5.2.1
What is Air Pollution?
Air pollution is the introduction of many kinds of
gases, chemicals, particulate matter or biological
materials into the atmosphere by humans
•Reduces the “Air quality”.
Look at that Beautiful Skyline!
Can you
spot the
pollution?
5.7.2 Outline the formation of
photochemical smog.
• Photochemical Smog is
a mixture of about 100
primary and secondary
pollutants formed under
the influence of
sunlight.
• Tropospheric Ozone is
the main pollutant!
Formation of Tropospheric Ozone
Tropospheric Ozone = “Bad Ozone”
1. Burning of fossil fuels emitted by automobiles,
gasoline vapors, and power plants creates NO
(nitric oxide), Volatile Organic Compounds
(VOC), and other hydrocarbons.
2. VOCs and NO reacts with Oxygen to form NO2
(nitrogen dioxide) a brown gas that contributes
to urban haze.
3. NO2 gets hit with a UV ray, breaking of a free
oxygen atom. This combines with an oxygen
molecule (O2) to form Tropospheric Ozone (O3).
4. When will ozone levels reach their peak in an
urban environment?
5. Is Ozone a primary or secondary pollutant?
http://airnow.gov
Sources of Tropospheric Ozone
EPA Graphic
Tropospheric Ozone Effects
1. Respiratory irritation
- bronchial constriction
- asthma
- coughing, wheezing
2. Eye irritation
3. Decreases crop yields
- slows plant growth
4. Damages plastics, rubber
and nylon
5. Has a harsh odor
Photochemical Smog
Thermal Inversions
A. Under normal conditions air rises and disperses
pollutants
B. A thermal inversion, occurs where a layer of
warm air sits over a layer of cooler air, which
prevents the dispersal of the pollutants.
C. The dense, cooler air becomes stagnant and
accumulates more and more pollutants.
D. Occurs in cities located in valleys surrounded by
mountains, with light winds and lots of people
driving cars!
-
Ex. Los Angeles, Mexico City, Beijing.
E. What will get rid of the pollutants?
Thermal Inversion
LOS ANGELES, SANTIAGO,
MEXICO CITY, RIO DE
JANEIRO, BEIJING, AND EVEN
DENVER, CO
London’s Great Smog of ’52
Los Angeles Overtime
A is from 1940’s
B is from 1960’s
C is from 1990’s
Places like Bejjing are so smoggy it
can be really hazardous to ones
health to breathe!
Beijing, China air on a day after rain (left) and a sunny but smoggy
day (right) August 2005.
Photo taken by Bobak Ha'Eri
CNN Report
Sunday 11/8/15
5.2.1 – Direct method of
monitoring air pollution
1. Schoenbein Paper = ozone
- using a mixture of starch, potassium iodide, and
water spread on filter paper
- The paper will vary in color depending on the amount
of the oxidation.
- Those that have a lavender appearance were
exposed to more ozone and, finally, those that look
dark purple had high ozone exposures.
- This is a qualitative test for comparison purposes
- Relative humidity can affect results
Evaluate this method:
5.7.3 – Describe and evaluate the
pollution management strategies for
urban air pollution
• Replace –
• Regulate –
– The U.S. Congress passed Clean Air Acts in 1970, 1977, and
1990. Brought on by smog deaths in PA
• National Ambient Air Quality Standards (NAAQS) were
established for six outdoor “criteria” (main) pollutants.
• Two limits were established: a primary standard is set to
protect human health and a secondary standard is set to
prevent environmental, property and crop damage.
• Restore -