As somebody with breathing problems air quality is always a concern for me. I was planning on moving into a 3yr old high rise condo building in Toronto. How good is modern ventilation in these buildings? I understand some of the new "green" condo's have individual HRV units in each suite providing a good intake of fresh air, however the building I would be moving into does not have this feature. So my question is how does ventilation work in your typical modern high rise condo building and how effective is this type of ventilation? What are the typical air changes per hour etc?