I kind of agree with HHII that the location you lived and the way your immune system developed determine the onset of your symptoms. An allergy to pollens after age 30 is also weird to me, but it may occur. You should be “lucky” enough to expose to the pollens at the “right” time and at the “right” age, so an unlikely diagnosis falls on you, if it were a true allergy. At first I wonder if your symptoms are caused by “non-allergic” rhinitis, especially vasomotor rhinitis, yet the seasonal features, watery eyes and spontaneous recovery seem to lead to an “allergic” one. But anyway, since most symptoms of these two are induced by the same cells (mast cells) and the same mediators (histamine), both anti-histamines and nasal spray work.
As for the mould and air pollution, the former can definitely cause allergic rhinitis, but the symptoms always persist throughout the seasons, so is called perennial rhinitis; whereas the latter always induces vasomotor rhinitis, instead, which symptoms occurred whenever exposed to irritant odors or car exhaust. So an allergic rhinitis can be seasonal, like hay fever, or can be perennial, like fungi allergy, and both of them are related to IgE. But a non-allergic rhinitis is almost not seasonal and it’s not an IgE-mediated problem. There are still other nose problems, such as mixed rhinitis, which is supposed to be the most common form of rhinitis, but its story is beyond the discussion here.