FOREST-FIRE ENHANCED PHOTOCHEMICAL AIR-POLLUTION - A CASE-STUDY

A large forest fire occurred about 300 km to the northeast of the Edmo nton area in early summer 1995. The forest fire produced nitrogen oxid es, hydrocarbons and ozone which were transported downwind. Continuous monitoring of O-3, NO and NO2 and integrated measurements of volatile organic compounds, together with air trajectories, during the period of 1-6 June indicate that air pollutant concentrations were enhanced b y the forest fire emissions. In the rural environment the influence of the forest fire on air quality could be easily detected; significantl y higher NO2 and O-3 concentrations were observed when air came from t he direction of the forest fire area. Hourly NO2 and O-3 concentration were 50-150% higher than the seasonal median values. The influence of the forest fire on air quality was also noticeable in the urban cente r even though local emissions are much higher than in the rural area. Maximum hourly ozone concentrations at the urban air quality monitorin g stations in Edmonton on 4 June 1995 were above the 82 ppbv national and provincial air quality objectives. (C) 1998 Elsevier Science Ltd. All rights reserved.