Smog: Tropospheric ozone

1. Smog: Tropospheric ozone

2. What is Smog? • Smog = smoke and fog • Two types of Smog • Industrial Smog: Also called London Smog. This is related to sulfur dioxide pollution • Photochemical Smog: Sunlight causes nitrogen monoxide and volatile organic compounds to react when there is a thermal inversion

3. Photochemical Smog • A complex mixture of air pollutants produced in the lower atmosphere by the reaction of hydrocarbons (VOC’s) and nitrogen oxides (NOx) under the influence of sunlight. • The most harmful components produced include ozone, peroxyacyl nitrates (PAN’s) and various aldehydes.

4. Primary and Secondary Air Pollution • Primary Air Pollution • Directly from the pollution source • nitrogen monoxide and volatile organic compounds (VOC’s) • Secondary Air Pollution - Forms when the primary pollutants react with each other in atmosphere.

5. Primary Pollutants • Nitrogen and oxygen react at high temperatures in the engine of cars to form NO, nitrogen monoxide • Unburnt fuel releases VOC’s, Volatile Organic compounds (These are also called hydrocarbons, HC’s)

6. Motor vehicles are the main polluters of NOx

7. Volatile organic compounds come from industry and motor vehicles

8. Normally, the temperature in the atmosphere decreases with altitude • Thermal inversion occurs when a warm layer is trapped between cold layers

9. Secondary Air Pollution • Nitrogen monoxide reacts with oxygen to form nitrogen dioxide. • Nitrogen oxides react with volatile organic compounds to form ozone and other nasty compounds.

10. When there is a thermal inversion, NO and VOC’s react in the sunlight to form ozone.

11. Tropospheric Ozone: O3 • Ground-level ozone is an air pollutant that is irritating and oxidizing. • It is harmful to breathe, it damages crops, trees and other vegetation, and it damages rubber and plastics • Tropospheric ozone is one of the main components of urban smog.

12. Thermal Inversion In Santiago, the smog contains ozone and PM10’s

13. Short term exposure to tropospheric ozone in smog can cause respiratory problems and nose and throat irritation.

14. Effects on Humans • Eye, nose and throatirritation • Coughing and wheezing • Breathingdifficulty • Reducedlungcapacity • Loweredresistancetoinfections • Increasedheart and lungconditions • Hospitalizations • Prematuredeath • Dangeroustochildren, elderly and peoplewithasthma

15. Tropospheric ozone damages plants: • Reduced agricultural yields • Reduced commercial forest yields • Reduced growth and survivability of tree seedlings • Increased susceptibility to diseases, pests and other stresses such as harsh weather. • Damage to foliage of trees • The nitrogen oxides related to tropospheric ozone also cause acid rain

16. Ozone damages leaves

18. Measures that are taken to reduce Smog • Reduce air pollution by keeping cars properly maintained and tuned. • During the summer fill the gas tank during the cooler evening hours. • Use public transportation. • Install catalytic converters on all vehicles. • Use low VOC paints and solvents • Dispose of paints and solvents properly

19. Catalytic Converter Lowers CO, NO and HC (VOC’s) emissions Water, nitrogen gas and carbon dioxide are released

21. Evaluation of the catalytic converter NO, VOC’s and CO are converted to water, carbon dioxide and nitrogen gas. • They are expensive. • Not every car in Santiago has one. • Not all of the NO and VOC’s are converted into the less harmful gases.

22. Response to smog • If the air quality index is too high, limit physical activity outdoors. • In severe conditions, stay home or indoors. • In Santiago, some cars are restricted from driving on pre-emergency days.

23. Bibliography http://www.region.peel.on.ca/health/smog/actions.htm http://www.conama.cl/portal/1255/channel.html http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AirPollution.html (John W. Kimball)