With health being a number one priority in everyone's life, it really is a good serious question. With flat roofs (Tar & gravel), there is a higher risk of black mold being present, whether in the walls or in the insulation. If your home was not built correctly by an Edmonton roofing company from the beginning, with proper venting then you need an expert to inspect your house as soon as possible.
It appears half the houses designed with flat roofs in Edmonton, most from over 30 years ago, were vented correctly and the other half not. Houses vented correctly usually have a continuous aluminum ridge vent running along the whole length of the peak. With this continuous vent is also a vented soffit. This being said, if one were to experience a split or a hole on the roof, a roofer in Edmonton will simply patch the roof, and if properly vented everything will dry up soon in a natural state.
Roofs that aren't properly vented will end up trapping moisture and hence will turn into black mold. I am not an expert on black mould, but a proper building inspector or in particular a flat roof inspector should be able to give you the correct advice. Any credible roofing contractor in Edmonton should be able to work with a qualified inspector, bearing in mind that there are roofing contractors that won't work with any roofing inspectors.
My best personal advice about a roofing contractor that won't work with a qualified inspector is to take this as a red flag. We are here to correct, fix and give you the proper service that you are paying for. That being said, I don't want to scare or panic anyone just because a leak has developed.
In over the 30 years of roofing experience, I find it is usually the roofs that have been ignored for lack of maintenance that pose the most risk. If your roof fall into this category call me for free advice, my name is Chris at XL Roofing in Edmonton, Alberta