Very smoggy, hazy AERIAL SHOTs of Montreal. ELS of helicopter flying through murk. ELS of smoking factory chimneys. Oblique circular AERIAL LSs of large factories emitting clouds of pollutant from chimneys. Oblique shot of factory, smoke, early morning. Circular AERIAL SHOT around tall smokestack belching smoke. TRAVELLING SHOT through smoke. Circular oblique AERIAL SHOT over squat plant with twin stacks, no smoke coming out, much snow.