13 terms

Tropospheric Ozone

•virtually no anthropogenic releases to air or natural O3 releases (except electrical storms)
Ozone Issues
• Bad O3 = ground level (tropo) O3 generation
• Good = strato O3 deletion
Steady State Trop O3 Production
• 40ug/m3
• issue: in urban atmosphere O3 conc. can be gx,10x,20x steady state
• can also be secondary pollutant due to: hydroxyl radical, UV light, warm temps, stagnant air, NO/NO2,NOx, NMHC and NMHC sinks from vehicle exhaust or industrial pt sources
O3 Sinks
• Rural Sink
• Polluted Atmosphere
Tropospheric Ozone in Urban Air
• tremendous amts of continuous air monitoring completed
Typical Smoggy Day in LA
• Before sunrise/Morning rush hour = NOx/NMHC reminan low in air
• Morning Rush Hour: sharp rise in NO/NMHC in proportion to vehicle traffic
• Earl-Mid Morning: NO concentrations being to fall as NO2/O3/aldehydes begin to rise
• Mid Morning: NO2 and NMHC concentrations peak
• Noon-Mid Afternoon: O3/aldehydes/PAN at max conc.; NO2/NMHC dropping
• Mid-Late Afternoon: O3/aldehyde/PAN drop
• Evening NO2 concentrations return to background levels
Smog Chamber
• using NMHC propene, No/NOx and irradiation by UV light: generate increasignn levels of ozone at expense of propene and NOx/NO
2 Phases of Ozone Accumulation
• Accumulating NO2 - in prescence of O2 and UV - generates additional O3
• Reactive HC also generate reactive aldehydes - which produce hydroperoxyl radicals that also react with NO and blocks O3 rxn with NO -> O3 accumulation
As UV diminishes...
• conversion of NMHC to peroxy acetyl radicals/aldehydes slows -> allow accumulated ozone to react with NO and produce NO2, O3 levels being to decrease
Health Effects of Tropospheric Ozone: Animals
• ciliated cells of MCE are injured plus pulmonary odema at high O3 conc due to low water solubility of O3 and damage to alveoli
• decreased MCE activity, inc respiratory disease, decreased gas transport across alveolar cells
• decreased pulmonary fncs
• aggravation of pre-existing respiratory illness
• inc hospital admissions for respiratory problems
• increased premature mortality
• MOST RECENT O3 causes asthma
• US: more than 100 cities above 1 hr guidelines
• Canada -> non-attainment areas = Lower Fraser River Valley and Windsor-Quebec City Corridor
AB 4 Action Levels in Tropospheric Ozone Management
• Baseline Monitoring and Data Gathering Level (annual/area basis) - best AQ; continue monitoring of ambient AQ levels
• Surveillance Action Level (baseline-58ppbv): take appropriate steps to ensure sources of eleveated concentrations are determing
• Management Plan Level (58-65 ppbv): prevent and exceedance of CWS, to maintain AQ and wherever possible to imporve; management plant developed and impletmented by stakeholders for source and receptor areas
• Mandatory Plan to Reduce Below CWS (>65 ppbv): develop and implement plan to reduce conc below CWS
Where does AB stand vs the Plan?
• only Edmonton seems to require management plan