Is it possible to prevent smoke coming into the house and how much would it cost?

Findingmorty asks:

My neighbors smoke like fiends and I'm having breathing difficulties. As best as I can tell, they smoke outside and it drifts up and into the attic via a permanent vent on the side of the attic. Then somehow it makes it's way into my room and the ventilation system. The A/C unit is on top of the house and come summer it will suck it in as well and blow it all throughout the house. Is there anything an HVAC professional can do about this and how much would it cost?

Can this issue be fixed? Yes, Will it be expensive? Yes. Your house is allowing outdoor air, which is contaminated with things such as your neighbors smoke, because your home is under a negative pressure and/or extremely leaky. The first thing I would do is find a reputable HVAC contractor who specializes in indoor air quality. They can examine your homes envelope and HVAC duct system and other venting systems like bathroom and stove exhaust to try to determine exactly how the smoke is making it into your living space. From there they should be able to recommend steps that can be taken to correct the home envelope. Another benefit to hiring a professional such as this is that many of the repairs needed to solve problems such this also benefit you by preventing the outdoor heat from entering your space in the summer which in turn can dramatically lower your electric bill. A less expensive option may be to purchase either a duct mounted whole home PCO type of air purifier or a standalone one. You will need one that either has an ionizer or PCO (Photocatalytic Oxidation) technology. Keep in mind that ionization will produce ozone so for some people can cause issues, however it is very good at getting rid of cigarette smoke. I hope this helps.

- James Bowman, National Technical Manager, HVACR