title: Characterization of an episode with elevated ozone concentrations.
abstract: A detailed analysis has been made of a seven day period in 1973, during which elevated ozone levels were observed at Ottawa. In addition to the ozone data, results are also presented for oxides of nitrogen, carbon monoxide, methane, total hydrocarbons and particulate matter. The particulates were analyzed for seven constituents, including the cations ammonium, calcium, sodium, potassium and lead and the anions sulfate and nitrate. Also measured were several other properties of the particulates, including the size distribution. It was found that none of the other gaseous pollutants showed any increase in concentration when high ozone levels were present. In contrast, the particulate matter did increase and several constituents, notably ammonium and sulfate, showed a dramatic rise. A comparison with ozone data from Toronto and upper New York state showed that the high ozone concentrations were widespread. A meteorological analysis showed that elevated ozone levels were associated with a Tropical air mass with a moderate southwesterly flow of air. Trajectory calculations were carried out to show the origin of the air over Ottawa before, during and after the period of increased ozone.
mesh_terms: D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D002118:Calcium / Q000032:analysis; D002170:Canada; D002248:Carbon Monoxide / Q000032:analysis; D006838:Hydrocarbons / Q000032:analysis; D007854:Lead / Q000032:analysis; D008697:Methane / Q000032:analysis; D008991:Monitoring, Physiologic; D009566:Nitrates / Q000032:analysis; D009589:Nitrogen Oxides / Q000032:analysis; D010126:Ozone / Q000032:analysis*; D011188:Potassium / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D012964:Sodium / Q000032:analysis; D013431:Sulfates / Q000032:analysis; D014887:Weather
chemical_list: D000393:Air Pollutants; D006838:Hydrocarbons; D009566:Nitrates; D009589:Nitrogen Oxides; D000644:Quaternary Ammonium Compounds; D013431:Sulfates; D007854:Lead; D010126:Ozone; D002248:Carbon Monoxide; D012964:Sodium; D008697:Methane; D011188:Potassium; D002118:Calcium