OZONE ATMOSPHERIC POLLUTION

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OZONE ATMOSPHERIC POLLUTION

• Ozone in urban smog

J (Hans) van Leeuwen
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Ozone in the atmosphere

• Ozone stratospheric good tropospheric bad
• Ground-level ozone resulting from
  NOx VOC sunlight
• Statospheric ozone is formed naturally and
  screens out harmful UV
• Ozone pollution is a regional problem as it
  travels 100s of miles

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Ozone production from NOx
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Ozone production from NOx
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Photochemical smog reactions

• N2 O2 ? 2NO
• 2NO O2 ? 2NO2
• NO2 h? ? NO O
• O O2 M ? O3 M
• O3 NO ? NO2 O2
• These reactions are cyclical with little net O3
• Hydrocarbons and water can remove NO

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Ozone production from NOx
Oxygen atoms freed from nitrogen dioxide by the
action of sunlight attack oxygen molecules to
make ozone. Nitrogen oxide can combine with ozone
to reform nitrogen dioxide, and the cycle
repeats.
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Free radical reactions in air

• O H2O ? 2OH.
• RH OH. ? R. H2O
• R. O2 ? RO2.
• RO2. NO ? RO. NO2
• RO. O2 ? HO2. RCHO
• HO2. NO ? NO2 OH.
• Build-up of NO2, O3 and aldehydes results
• - also PAN peroxyacetyl nitrate

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Free radical pathways to O3
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Diurnal variations in NOx and O3
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LA smog
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Hourly Air Quality Report
http//www.airnow.gov/
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Key NOx control for coal boilers
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NOx control on cement plants
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http//www.sonomatech.com/smogcity/ Use this to
see the effects of weather And human activities
on ozone levels
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Ozone damage to lungs
This photo shows a healthy lung air way and an
inflamed lung air way. Ozone can inflame the
lung's lining, and repeated episodes of
inflammation may cause permanent changes in the
lung.
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Ozone damage to plants
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Ozone Concentration (ppm) Air Quality
Air Quality(8-hour average, unless noted)
Index Values Descriptor 0.0 to
0.064 0 to 50
Good 0.065 to 0.084 51 to 100
Moderate 0.085 to 0.104 101 to 150
Unhealthy (sensitive groups)0.105
to 0.124 151 to 200 Unhealthy 0.125
(8-hr.) to 0.404 (1-hr.) 201 to 300 Very
Unhealthy
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This map shows ozone levels in the eastern
United States on August 24, 1998
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http//www.epa.gov/cgi-bin/airnow.cgi?MapDate
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61-79ppb
80-99ppb
100-110ppb
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125 O3
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http//www.epa.gov/airnow
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Ozone levels today http//airnow.gov/
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EPA Air Quality Index Levels of Health Concern Ozone Air Quality Conditions
0 to 50 Good The air quality for your community is considered satisfactory and air pollution poses little or no risk.
51 to 100 Moderate Air quality is acceptable however, people who are unusually sensitive to ozone may experience respiratory symptoms.
101 to 150 Unhealthy for Sensitive Groups Children and adults who are active outdoors and people with respiratory disease are at greater risk from exposure to ozone. When values are between this range members of sensitive groups may experience health effects. The general public is not likely to be affected when ozone levels are in this range.
151 to 200 Unhealthy Everyone may begin to experience health effects. Members of sensitive groups may experience more serious health effects.
201 to 300 Very Unhealthy Ozone levels between 201 and 300 trigger a health alert, meaning everyone may experience more serious health effects.
301 to 500 Hazardous Ozone values over 300 trigger health warnings of emergency conditions. The entire population is more likely to be affected. Hazardous ozone values are extremely rare in the U.S.