You would see ticket sales from time to time from Porter Airline. Please don't be fooled by that! I just realized that myself which was a big surprise.
I was watching for tickets from Chicago to Toronto on their website few days ago. I got a price $185 return that day. It was very cheap! I told my friend right way to tell him if he want to book it. Few days later, my friend had not booked ticket, but the airline now having "50% off sale". I checked ticket again, now the cheapest fare is $294 return. It's after "50% off base fare".
So please don't be fooled by their ad saying it's the biggest sale of the year. It's just the biggest time to trick YOU!
I think as nowadays air travel is not a pleasant thing to do, I found people who likes Porter Airline not necessary that they like Porter, it's because they hate Air Canada.
As for the airport vs. environment.
I live at Harbour front right at edge of water on 28th floor. You would think high up with lake view must have good air from lakeside. NO! I have a balcony with a table and chairs outside. I have to clean my table everyday. My paper towel is black! Think about it over, we should not be surprised: airplane is the the biggest polluter for the air quality in terms of our daily life.
I travel a lot. Sometimes I see some flights only carry few passengers and without reduce the ticket price. That fact is just spoken for its self: profit first.