I love having a heat recovery ventilation system (HRV). It’s a system that expels stale (or toxic air) and brings in some kind of filtered fresh air from outside.
It’s great, unless it’s not working or is sucking in toxic chemicals from the outdoor air.
Someone recently asked me how I was able to keep so many of my things, including some that might still be off-gassing toxic chemicals, and the HRV is the answer. Without the HRV I would have to give up even more of my possessions than I already did.
The one here has broken down a number of times since I arrived, leaving me without fresher indoor air for days, or even weeks at a time, which is a problem because my brain becomes sluggish when I don’t have decent air to breathe…
The unit here is 17+ years old, and the company doesn’t offer activated carbon filled filters for the model that was installed. Activated carbon filters would be helpful, even necessary for people with MCS to have, since the carbon in those filters helps remove things like the toxic VOCs from laundry products, woodsmoke, BBQ fuels, etc (name your outdoor poisons). Instead, I have had to turn the unit off whenever those fumes are being sucked inside, and turn it back on when it’s safe to do so again, when the air outside is no longer saturated, usually when the wind has changed directions, or late at night after people stop doing laundry and shut down their fireplaces. That might be why this unit has been breaking down, in addition to its age, it might not have been designed to be shut off and on so frequently.
I did find a place (NEEDS) that sells custom made filters for furnaces and they could make some for the HRV, but they would cost around $50 each + shipping, and would need to be replaced every 3 months. The current filters, which are provided, cost about $10 each. They won’t provide the carbon ones, and I can’t afford them on my own.
If I could find a fragrance free medical professional who would make a house-call, they could fill out forms and ODSP might fund them, since I heard they do fund furnace filters, but I haven’t been able to find any healthcare professional willing to do so despite the Accessibility Standards… but that’s a blog post for another day…
In the meantime, I’ll leave you with some links below, in case you want to explore HRV’s and filters
How to Get the Ventilation That You Need in Your House
http://www.cmhc-schl.gc.ca/en/co/maho/yohoyohe/inaiqu/inaiqu_009.cfm
Heat Recovery Ventilator
Natural Resources Canada’s Office of Energy Efficiency
http://oee.nrcan.gc.ca/publications/residential/hrv/7884
Types of filters available by one brand (there are others, this was just the 1st that came up in my search for carbon filters)
http://www.venmar.ca/en/filtrationpage.aspx
Custom made filters with activated carbon
Seriously "Sensitive" to Pollution 
As I was thinking about clean air per your post, above, I happened to notice that great sign in the photo. Where did you find/make such a sign? I’m in the U.S. and have never seen such a sign here. Needless to say, I love it. :-)
The non-profit housing board had 2 made for the other side of the building because people cut through there on their way elsewhere. The top part of the signs say “No Trespassing”.
I’m pretty sure you could call almost any sign-maker to have one made.
I should have mentioned that the current filter is a MERV 13 pleated filter that is 12″ x 24″ x 4″.
Does anyone know of any place to get a carbon filter that size other than NEEDS?
I’ve written an update:
http://lindasepp.wordpress.com/2012/11/17/hrv-and-mcs-an-update/