Moved into apartment and our HVAC is venting secondhand smoke into our unit. How to proceed?

Me (22) and my partner (23) signed our lease after viewing a basement unit in late August and thought it was a pretty good deal for the space and amenities included, although me and my partner both noticed a stale cigarette smell in the unit when touring. Ignoring this red flag we decided to go ahead and sign the lease, thinking the place needed a good airing out and cleaning (it seemed like no one had lived in the unit for a couple months, considering the amount of dust and cobwebs). After extensive airing out, cleaning and deodorizing, the smell persisted and I eventually discovered it is being blown in from our ceiling HVAC vents. This led me to believe the neighbours were heavy smokers at best or indoor smokers at worst, which is indicated against in our lease. I have contacted my landlord to begin investigating this issue, as my partner and I have respiratory issues and don't really want to be inhaling secondhand smoke 24/7.

My main concern is if this property was clearly advertised as non-smoking, will it be possible to reneg on the lease? I'm doing some research on LTB laws and tenant rights and found a clause referring to secondhand smoke interfering with reasonable enjoyment of the space which is definitely the case. Is there anything else I should be aware of moving forward should we need to get out of our lease early if this issue isn't resolved?