1. EXAMPLES OF AIR POLLUTION PROBLEMS
CHAPTER 2
EXAMPLES
OF AIR POLLUTION PROBLEMS

2. EXAMPLES OF AIR POLLUTION PROBLEMS
Classical urban Air Pollution
Modern urban Air Pollution
Acid rain
Greenhouse effects
Ozone depleption

3. Classical urban Air Pollution
"smog" = smoke + fog (London, 1952)
sulphur, soot, water vapour => acid aerosol

4. Modern urban Air Pollution
Stagnant air
Continuing emissions
"summer" (photochemical) smog:
NO, NO2, CxHy, UV-rad: ==> O3
(reactions worked out on blackboard)
Winter (cold weather) smog:
fine or ultra-fine particles ==> health effects
Mixture is different in different cities
Traffic important source
Toxicological mechanism still unknown
Health effects even at low concentrations
(from 40 mg/m3?)

8. Acid Rain
Dry and Wet deposition of (potentially) acidifying substances onto the earth's surface.
* so: not just rain!

9. ACID RAIN FORMATION

10. Acid Rain Process

11. Acidifying compounds SO2 and NOx (direct)  H2SO4 and HNO3
NHx (indirect by nitrification):
(NH4)2SO O2  2HNO3- +
H2SO4 + 2H2O

12. Effects of acid rain Plant injury (direct by SO2, NH3, (NO), NO2)
Change in mineral balance in soils (=> heavy metals)
Acidification of waters

13. Effects of acid rains

14. Deposition dry deposition (direct from air to surface):
proportional to concentration
important close to source (areas)
wet deposition (by rain, snow, hail, etc.)
rain cloud "washes" air mass
origin of air mass important
only when it rains
occult deposition (direct from fog or clouds)
only in areas with many fogs (mountainous areas)

15. Critical loads concept
That amount of (total) deposition that an ecosystem can "handle" for a prolonged time

16. Geographic distribution of acid rain

17. Greenhouse effects Radiation balance of the earth (figure 2.2)
Incoming solar radiation (short wave)
Outgoing black-body radiation (long wave - infrared)
(figure)
Temperature of earth is equilibrium
Natural greenhouse effect
Change in any term changes temperature

21. Projected temperature change

22. Radiative forcing
Any change in the balance Greenhouse gases: CO2, CH4, N2O, CFC's, (O3)
Increasing concentrations (figures)
=> enhanced greenhouse effect

26. Factors of importance Concentration increase rate Atmospheric lifetime
==> Global warming potential
(Table 2.2 and 2.3)

30. Ozone depletion Ozone layer (20 - 50 km height; figure)
Absorbs UV-B (figure 2.3)
Thickness of ozone layer
30 km but 3 mm pure O3 at 100 hPa!
3 O2  2 O3 (UV-B radiation needed)
NO2  NO + O (UV-A radiation)
Four groups of substances interfere (eq )

34. Ozone hole due to heterogeneous reactions:
in Antarctic winter Polar Stratospheric Clouds
collect chlorine compounds
set free in Spring (September)
eq. 2.17

37. Health Effects

38. Thank you