How harmful is white mold?

How harmful is mold if it's been dried on a ceiling for years, but never cleaned?

• We are cleaning an old rental house and discovered dried on mold which we were told has been there for 2 years and not cleaned , but dry. I walked in to the closet and it made me cough. Is it still fixable?

• Answer:

  A number of commonly found mold species are, in fact, toxic mold, a description applied to any mold that produces mycotoxins in its spores. Stachybotrys (black mold), Aspergillus, and Penicillium are three of the most dangerous and commonly found indoor toxic molds. Mycotoxins are cytotoxic, meaning they have the capacity to pass through the human cellular wall and disrupt certain cellular processes – potentially causing serious health damage to workers and customers. Respiratory inflammation triggered by mildew and mold allergies attacks the nasal passages, as MayoClinic.com relates. Runny-nose symptoms may alternate with nasal and sinus congestion and postnasal drip. Cases brought on by severe mildew problems can cause sinusitis, a painful sinus condition that may take longer to resolve than the usual irritation and allergy symptoms. Lengthy exposure or high levels of fungal allergens can extend inflammation to the throat and airways, generating coughing and wheezing as the lungs work harder to inhale and exhale. Health effects from isolated incidents may not recur in patients with low-level sensitivities. MayoClinic.com reports, however, that these symptoms can cause asthmatic persons with mold allergies to experience shortness of breath and potential respiratory emergencies. These symptoms can arise from any level of mold contact.