What are the symptoms of chronic formaldehyde poisoning?

Chronic formaldehyde poisoning may cause symptoms such as tearing and headache. Patients mainly present with nasal irritation symptoms including runny nose, dryness of the nose, nasal congestion, and purulent nasal discharge. It may also lead to tearing, eye irritation, blurred vision, as well as skin damage and rashes—systemic dermatological manifestations. If inhaled into the lungs, it can cause chest tightness, coughing, sore throat, and difficulty breathing, and may even result in wheezing.