In October 2014, plaintiff Safi Nairobi, a retiree, complained to her landlords, Kirk Watkins and Cindy Watkins, of a roof leak that occurred in her studio apartment during a rainstorm. Nairobi lived at the apartment, which was located at 3033 MacArthur Boulevard, in Oakland, since July 2009. The Watkinses hired roofers to fix the leak, and then hired workers to replace the wet carpet. In December 2014, two months after the leak was reported, Nairobi complained that she smelled mold. The next month, the Watkinses hired Mycodry Restoration Systems to investigate the complaint of mold and then remediate the studio. Nairobi claimed that despite those efforts, the Watkinses failed to adequately remediate the property, which exposed her to toxic mold. She also claimed that there were other conditions of the studio that made it uninhabitable. Nairobi filed complaints with the Oakland Rent Board and the Oakland Building Department, claiming that the studio was not certified for occupancy and that it was uninhabitable at the time the Watkinses first rented it to her in 2009. Nairobi also claimed that the Watkinses knew the studio did not have a certificate of occupancy. However, the Watkinses maintained that they believed the studio had a certificate of occupancy and that they consistently responded to Nairobi whenever she had complaints about the condition of the studio. The Watkinses were ultimately advised by the city of Oakland that the studio did not have a certificate of occupancy and that as a result, the studio apartment would have to be removed from the housing market. The Watkinses immediately gave notice to Nairobi that she would have to vacate the premises. However, Nairobi would not vacate the premises, so the Watkinses brought an unlawful detainer action against her. The action was settled by making a cash payment to Nairobi on the condition that she leave the premises by Jan. 1, 2016. Nairobi sued Kirk Watkins and Cindy Watkins shortly after vacating the premises. She alleged that the Watkinses’ actions constituted a failure to repair, a breach of contract, a breach of the warranty of habitability, negligent misrepresentation, fraud, violations of Business & Professions Code § 17200, and an intentional infliction of emotional distress. The Watkinses filed a third-party complaint against the company they had hired to remediate the studio after Nairobi complained of the smell of mold, Mycodry Restoration Systems, seeking for indemnification. The Watkinses settled with Mycodry prior to trial. The Watkinses claimed that they immediately responded to the roof leak, including running to get buckets to catch the water when first advised of the situation, and then retained professionals to fix the leak and replace the carpet. They also claimed that they then retained a professional to remediate the property once Nairobi complained of the smell of mold. However, the Watkinses claimed that there was no evidence of toxic mold present in the studio., Nairobi claimed that she suffered mold toxicity and mycotoxin poisoning. She alleged that her exposure to mold caused permanent physical , including a severely compromised immune system, skin lesions, dermatitis, a sore throat, cognitive and memory problems, and severe emotional distress. Defense counsel contended that Nairobi suffered little or no health effects from being exposed to low levels of common molds during her tenancy and that there was no possible causal connection between her prior residency in the studio and her post-tenancy subjective complaints to her treating doctors. The defense noted that, on cross-examination, Nairobi’s primary care physician from UCSF Health testified that molds are in the environment all the time and that if Nairobi was ill due to exposure to toxic mold, one would have expected her to be very sick, which did not happen. The defense also noted that the physician reportedly agreed that Nairobi had no symptoms consistent with systemic mold exposure and that Nairobi was not immunocompromised. Defense counsel reported that Nairobi’s non-retained expert, Dr. Stephanie McCarter, conceded on cross-examination that she had only reviewed one of Nairobi’s medical records from UCSF (out of hundreds of pages), after testifying on direct examination that she had read all of them. The non-retained expert also testified that she understood that the physicians at UCSF who treated Nairobi were of the opinion that Nairobi was not immunocompromised, and opined that the UCSF doctors were wrong and that she was right. Defense counsel added that Nairobi’s retained medical expert, an allergy and immunology physician, testified extensively to his opinions, which were contained in his report dated April 2019, but conceded under cross-examination that he had not seen Nairobi nor examined her before he prepared his report. The expert also admitted that he did not review Nairobi’s UCSF medical records, but based his testimony as to Nairobi’s exposure to mold and mycotoxins on a Real Time Lab report dated October 2016. He then conceded on cross-examination that the October 2016 Real Time Lab report did not contain Nairobi’s lab results, but, rather, the lab results of another patient and that the report was for the wrong patient. In addition, the expert conceded under cross-examination that he was wrong when he testified that the mycotoxin Trichothecene was present in significant levels in Nairobi’s system and that the lab report for Nairobi did not show, or was equivocal, as to the presence of several mycotoxins, including Trichothecene.