Since 2000, plaintiff Deanna Dailey was exposed to microscopic air borne particles of pigeon feathers and feces (antigens) that got into the air circulating in her apartment in Yuba City through an open condensate drain tube of the roof-mounted heat pump (HVAC unit). As a result, in December 2010, Dailey, a disabled 60 year old, was diagnosed with hypersensitivity pneumonitis and pulmonary fibrosis, or bird fancier’s lung, which was caused by the bird droppings. Dailey sued the property owner, the property management company and the HVAC contractor. Dailey claimed the HVAC contractor improperly installed and maintained the HVAC unit, as the drain tube should have been connected to a trap, which would have prevented the particulate matter from entering the circulating air. She also claimed the property owner and property management company failed to abate the known problem of a pigeon infestation on the roof and around the HVAC equipment, and that they maintained a dangerous condition by keeping the HVAC unit open to outside air, when it was only designed to be self-contained. Defense counsel asserted that none of the defendants were negligent because Dailey’s disease was not foreseeable. Counsel for the HVAC contractor also asserted that there was no negligence in the maintenance of the HVAC equipment., Dailey was diagnosed with hypersensitivity pneumonitis and pulmonary fibrosis, or bird fancier’s lung, in 2010. Dailey initially underwent treatment for lung disease, which included four inpatient stays at a local hospital for pulmonary therapy. However, when blood tests were positive for antibodies due to exposure to a mixture of feather and pigeon dropping antigens, she became an inpatient at UCSF Medical Center at Mount Zion in San Francisco. During that time, she underwent 10 weeks of oxygen and steroid therapy, while she lost weight waiting for donor lungs. Finally, on July 7, 2011, a double lung transplant occurred at UCSF Medical Center at Mount Zion. Defense counsel disputed causation as to Dailey’s lung condition.