we bought an old house that's using oil heating system...when the heat is on there's a smell to it... we can't really keep any plants in-door in the winter months...why is this and what does this smell mean? we recently noticed that in the basement by the heating pipes there are these lillte black particals on the floor could this be because we've let the tank go too low before re-fueling? And is all this hazardous?

Plz help us figured out with these problems are if possibles...many thanks