OTTAWA — An orange haze blanketed Toronto on Wednesday as wildfire smoke moved into the city, temporarily giving Canada’s largest city the worst air quality in the world.Smoke from forest fires in northwestern Ontario drifted south overnight, reducing visibility and leaving the city’s skyline under a thick orange-grey cloud.Toronto reached the top of IQAir’s real-time global air-quality ranking at about 8 a.m., though the rankings can shift throughout the day as conditions change.Environment Canada upgraded its air-quality warning for Toronto to an orange alert Wednesday morning, indicating a high impact and high forecast confidence.The weather agency said smoke was producing poor air quality and reduced visibility across much of southern Ontario, with hazy conditions potentially continuing into Friday morning in some areas.“As smoke levels increase, health risks increase,” Environment Canada said. “Limit time outdoors. Consider reducing or rescheduling outdoor sports, activities and events.”The smoke prompted the City of Toronto to cancel Wednesday’s FIFA Fan Festival at Fort York and The Bentway.“The decision was made to prioritize the health and safety of attendees, as well as police, fire, paramedics, event staff, volunteers and other personnel supporting the event, as they would be exposed to air-quality conditions for an extended period of time,” the city said..Officials said cancelling the festival would also allow Toronto police, firefighters and paramedics to remain available for other public-safety demands.All outdoor CampTO field trips and registered outdoor programs were also cancelled, postponed or moved indoors where possible.The smoke arrived as Toronto remained under a heat warning, with high humidity worsening the health risks associated with poor air quality.Environment Canada said wildfire smoke can cause eye, nose and throat irritation, headaches and coughing. More serious symptoms can include wheezing, chest pain and severe coughing.People aged 65 and older, pregnant women, infants, young children, outdoor workers and those with existing health conditions are considered particularly vulnerable.Residents were advised to keep windows and doors closed where possible, reduce strenuous outdoor activity and prioritize staying cool during the continuing heat.