Embed Size (px)
Citation preview
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
• Cause harm to humans or other living
• organisms.
• Damages the natural environment.
• Reduce the air quality.
•Cause harm to humans or other living organisms.
•Damages the natural environment.
•Reduce the air quality.
5.7.1 State the source and outline the effect of tropospheric ozone.
1. Source of Tropospheric Ozone “Bad Ozone”a. Burning of fossil fuels emitted by automobiles, gasoline
vapors, and power plants creates NO (nitric oxide) and other hydrocarbons called Volatile Organic Compounds (VOC)
b. VOC’s and NO reacts with Oxygen to form NO2 (nitrogen dioxide) a brown gas that contributes to urban haze.
c. NO2 absorbs sunlight, and when it breaks up, the free oxygen atoms combine with other oxygen molecules to form Tropospheric Ozone.
d. When will ozone levels reach their peak in an urban environment?
e. Is Ozone a primary or secondary pollutant?
Sources of Tropospheric Ozone
EPA Graphic
http://airnow.gov
Tropospheric Ozone Effects
1. respiratory irritation- bronchial constriction - asthma
- coughing, wheezing • eye irritation • decreased crop yields
- slows plant growth
1. damages plastics
2. breaks down rubber
& nylon
6. harsh odor
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.
• Ozone is the main pollutant!
Photochemical Smog
Thermal Inversions
A. Under normal conditions air rises and disperses pollutants
B.B. A A thermal inversionthermal inversion, occurs where a layer of , occurs where a layer of warm air sits over a layer of cold air, which warm air sits over a layer of cold air, which prevents mixing prevents mixing
C.C. The dense, colder air becomes stagnant and The dense, colder air becomes stagnant and accumulates more pollutants.accumulates more pollutants.
D. Occurs in cities located in valleys surrounded by mountains, with light winds and lots of people driving cars!
- i.e. the local topography.- Ex. Los Angeles, Mexico City, Beijing.
Los Angeles, Santiago, Mexico City, Rio de Janeiro, Sao Paulo,
and Beijing
Los Angeles OvertimeA is from 1940’sB is from 1960’sC is from 1990’s
Beijing, China air on a day after rain (left) and a sunny but smoggy day (right) August 2005.
Photo taken by Bobak Ha'Eri
Places like Bejjing are so smoggy it can be really hazardous to ones
health to breathe!
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 qualititative test for comparison purposes
- Relative humidity can affect results
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 The U.S. Congress passed Clean Air Acts in 1970, 1977, and
1990.1990.• National Ambient Air Quality Standards National Ambient Air Quality Standards (NAAQS)(NAAQS) were were
established for six outdoor “criteria” (main) pollutants.established for six outdoor “criteria” (main) pollutants.
• Two limits were established: Two limits were established: a primary standarda primary standard is set to is set to protect human health and protect human health and a secondary standarda secondary standard is set to is set to prevent environmental, property and crop damage.prevent environmental, property and crop damage.
• Restore -
