About 20 U.S.-bound flights from Montréal-Pierre Elliott Trudeau International Airport were cancelled Wednesday morning after an odour linked to construction materials forced U.S. Customs and Border Protection to suspend operations in the airport’s preclearance area.
The disruption on July 29, 2026 affected passengers booked on early flights from Montreal to the United States. Aéroports de Montréal said it was working to restore operations but initially provided no reopening time.
What happened at Montreal airport?
A strong odour was detected where passengers complete U.S. immigration and customs checks before departure. USCBP stopped processing travellers, preventing airlines from using the normal preclearance system.
ADM described it as an “odour from construction materials.” Some local reports called it a strong paint smell connected to overnight work, but airport officials did not initially identify the exact material.
An ADM spokesperson later confirmed that the source had been located. Ventilation was increased while authorities inspected the area and prepared it for reopening.
Were passengers evacuated?
Travellers were directed out of the affected section. Local reports estimated that around 300 people may have been evacuated, although ADM did not confirm an official total in its initial statement.
Abraham Wexler, who was waiting for an early flight to Fort Lauderdale, told CJAD 800 that security personnel moved travellers from the area. He said the U.S. customs counters were unstaffed and reported seeing two or three ambulances.
Officials did not announce any serious injuries or hospitalizations.
Was the odour dangerous?
An inspection by the Montreal Fire Department determined that the situation did not pose a health risk, according to an update released during the disruption. The airport used additional ventilation to clear the affected area.
The customs suspension appears to have been a precaution while authorities investigated the source. It did not represent a complete closure of Montreal-Trudeau Airport.
Which flights were affected?
Approximately 20 flights to U.S. destinations had reportedly been cancelled during the morning. Departure information also showed disruption involving routes such as Chicago O’Hare and Washington National.
The number could change as airlines updated their schedules. Later flights could also be delayed because of passenger queues, displaced aircraft and travellers needing alternative bookings.
The problem directly affected U.S.-bound departures requiring preclearance. Domestic Canadian flights and international services to countries other than the United States were not automatically cancelled.
Why did the customs suspension stop flights?
Passengers flying from Montreal to the United States generally complete American immigration and customs checks before boarding. They can then arrive in the U.S. without going through the same inspection after landing.
When USCBP cannot operate the Montreal facility, airlines cannot process passengers through the usual departure system. ADM’s official guide explains the U.S. customs procedure at Montreal-Trudeau.
This is why an incident limited to one airport section can disrupt flights to several U.S. cities even when runways and other terminals remain operational.
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What should affected passengers do?
ADM advised passengers to check with their airline before travelling to YUL. An earlier booking confirmation should not be treated as proof that the flight is still operating.
- Check the airline’s app, website, email and text alerts.
- Confirm whether the flight is cancelled, delayed or rescheduled.
- Ask the airline about refunds, rebooking and connecting flights.
- Keep receipts for additional meals, transport or accommodation.
- Allow extra time if the flight remains scheduled.
Questions about U.S. preclearance should be directed to USCBP. Ticket, baggage and refund questions should go to the operating airline.
Travellers seeking another route should compare connection times, fare conditions and refund rules. The advice provided after Frontier Airlines suspended its Knoxville flights may help passengers understand their rebooking choices.
Will passengers receive compensation?
Compensation is not automatic for every cancellation. Eligibility can depend on why the disruption occurred, how long it lasted, whether it was within the airline’s control and what replacement travel was offered.
Passengers should request written confirmation of the cancellation reason. Travellers considering a replacement ticket may also find the booking-condition guidance in the Qantas international flight sale useful when comparing alternatives.
Delays may continue after preclearance reopens while airlines accommodate displaced passengers. Checking directly with the airline before leaving home remains the best way to avoid an unnecessary trip to YUL.
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