Toronto Pearson International Airport is probably the low point in many people's vacation plans, and for those flying in and out of the city this week, it's about to get a whole lot worse.

Pearson Airport has issued a notice warning passengers of delays for both departures and arrivals as the Canadian border reopens to fully-vaccinated international visitors, which happened on September 7.

The warning explains how to best prepare for the many changes that passengers face compared to their pre-pandemic airport experiences. This includes new government travel requirements, additional screening, and health checks, all of which can drastically slow an already cumbersome pre-flight scramble.

Domestic passengers departing Pearson Airport have it comparatively easy, being advised to show up 90 minutes before flights to allow time for all of the added screening measures.

For international departures, you might want to bring along some reading material, as passengers are being asked to show up a full three hours before their flight.

International departures at Toronto Pearson International Airport.

In an effort to help smooth the painful process, departing passengers are advised to check-in for their flight online from home and then use one of the airport's touchless check-in kiosks to drop off luggage.

Passengers headed to international destinations should take extra care to review that country's travel requirements with their airline. More details about what departing passengers can expect can be found at Pearson's Travel information hub and "What to expect" page.

The biggest headaches and delays are in store for those arriving at Pearson Airport, with a post-flight process that can take longer than three hours for some passengers.

International flight arriving at Toronto Pearson International Airport.

Passengers will have to wait in a queue for space to free up in the customs hall, where their long processing period starts. This includes a screening by the Canada Border Services Agency (CBSA) and presenting a passenger's ArriveCAN app submission.

Some may even have to speak with Public Health Agency of Canada officials for further questioning before finally picking up their luggage.

All unvaccinated travellers will be subject to testing. While most fully vaccinated travellers will be exempt from this process, a select unlucky few will be randomly selected to be tested for the virus.

Pearson advises passengers arriving at Pearson to review the airport's Travel info hub, download the ArriveCAN app, and review Canada's travel requirements.

On top of the advisories, the airport reiterates that masks are mandatory for all passengers and airport employees in all terminal spaces, a rule that has not always been adhered to over the last year and a half.