It examines hospitalization rates for respiratory and circulatory diseases in relation to residential distance from a pollution-emitting facility and uses Toronto and Montreal as case studies to explore the relationship between heat extremes and health service utilization for respiratory and circulatory diseases. ###>Enfin, il se penche sur les cas de Montréal et de Toronto pour examiner la relation entre les chaleurs extrêmes et l’utilisation des services de santé en raison de problèmes respiratoires et circulatoires.