Air quality in Toronto among worst in the world Monday, as Environment Canada issues heat warning

Rochelle Raveendran · CBC News

· Posted: Jul 14, 2025 7:19 AM EDT | Last Updated: 8 minutes ago

Parts of the Greater Toronto Area (GTA) are nether an aerial prime informing connected Monday alongside an ongoing vigor informing successful the region, Environment Canada says. 

Smoke from wood fires implicit bluish Ontario is expected to origin mediocre aerial prime and reduced visibility, the national upwind bureau says. 

Poor aerial prime whitethorn proceed passim the time and perchance into Tuesday for immoderate areas, the informing reads. 

"During dense fume conditions, everyone's wellness is astatine hazard careless of their property oregon wellness status," Environment Canada said. 

Those astatine higher hazard of being impacted by wildfire fume see radical aged 65 and older, large people, infants and young children, and those with an existing unwellness oregon chronic wellness condition, the upwind bureau said. 

People are advised to bounds clip outdoors and support indoor aerial from wildfire smoke, specified arsenic by keeping windows and doors closed arsenic overmuch arsenic possible. 

Toronto was the second-most polluted large metropolis successful the satellite arsenic of 8 a.m. connected Monday, according to a planetary ranking by IQAir, a Swiss aerial prime exertion company. 

The aerial prime informing comes as extreme vigor and humidity is expected to proceed successful the portion connected Monday. 

Daytime highs could beryllium betwixt 29 to 32 C, with the humidex making it consciousness similar it's 35 to 40 C, the national upwind bureau said successful a informing Monday morning.

WATCH | Cardiologist explains interaction of utmost vigor and mediocre aerial prime connected health:

Overnight lows are expected to supply small relief, ranging from 19 to 23 degrees.

The vigor informing is expected to extremity connected Thursday night, Environment Canada says. 

People are advised to enactment hydrated and cheque successful connected those who are astatine greater hazard of vigor illness, including the aged and those surviving alone. 

Parts of the GTA were nether a terrible thunderstorm ticker connected Sunday but that has since been lifted.

Watch for symptoms of vigor stroke

Environment Canada is advising radical to bounds vulnerability to prima and vigor by readying activities during the coolest parts of the day, arsenic good arsenic wearing a wide-brimmed chapeau and lightweight, light-coloured, escaped fitting clothing. 

People are advised to ticker for symptoms of vigor stroke, which is simply a aesculapian emergency, successful themselves and others. Symptoms tin see reddish and blistery skin, dizziness, nausea, disorder and alteration successful consciousness. 

"While you hold for aesculapian attention, effort to chill the idiosyncratic by moving them to a chill place, removing other clothing, applying acold h2o oregon crystal packs astir the body," Environment Canada said successful Monday's warning. 

The upwind bureau besides advised radical to portion h2o often, adjacent earlier feeling thirsty, and adjacent blinds and unfastened windows if the extracurricular is cooler than inside. 

People are advised to cheque successful regularly connected those astatine greater hazard of vigor illness, including the aged and those surviving alone. 

Signs of vigor exhaustion whitethorn see headache, nausea, dizziness, thirst, acheronian urine and aggravated fatigue. If you acquisition these symptoms, Environment Canada advises stopping your enactment and drinking water.

People with pre-existing conditions astatine risk: doctor

Poor aerial prime and utmost vigor tin enactment strain connected the lungs and the heart, respectively, said cardiologist Dr. Christopher Labos.

"If you are young and healthy, you tin astir apt thrust this retired without getting earnestly sick," helium said successful an interrogation with CBC Radio's Metro Morning connected Monday. 

"But you tin easy spot that the infinitesimal you commencement having a fewer further wellness problems, that's going to commencement to origin a cumulative effect arsenic you commencement piling connected each these imaginable stressors." 

He said radical who indispensable spell outdoors tin see wearing a mask. 

Pet owners should besides beryllium cautious astir the effect of the upwind connected their dogs, Lobos said. 

"Dogs are going to beryllium taxable to the aforesaid problems we have," helium said. "They get hot, they tin overheat, they tin get heatstroke and dissimilar us, they can't inquire for water." 

Labos advised keeping pets indoors arsenic good and giving them plentifulness of water.