I've been in possession of some outdoor subsurface vapour readings for a while now. As of today I've got some indoor vapour readings and I find them alarming. Interestingly the MECP had only sent TCE (trichloroethylene) indoor readings to this particular homeowner. He requested the complete lab reports and received them promptly. They tell a somewhat different story with a multitude of low level readings from quite a few chemicals of differing toxicities. The outdoor readings are from vapour probes installed in streets and possibly boulevards for numerous streets between the former IMICO foundry on Beverley St. and the Eramosa River. These outdoor vapour probes have concentrations in excess of the criteria for TCE routinely and for Vinyl Chloride (VC) a breakdown product of TCE just once.
The problem arises with the fact of the very high readings in the soils around these older homes. Vapour intrusion occurs depending upon the integrity of the poured concrete foundations or even the concrete block foundations in older homes. Also any seals around in and out going water pipes, sewer pipes, elecrical, gas etc. can permit toxic vapours to enter if they are presnt in the nearby soils. Keep in mind each and every house will have greater or lesser resistance to vapor intrusion based upon the factors listed as well how many windows are open etc.
i.e. open windows dilute the vapours that have entered from the basement
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