Fungi are a major environmental allergen. 1 Exposure and sensitization to environmental fungi are associated with asthma onset, severity, and exacerbation. 2 Furthermore, fungi pose a risk for the development of more severe conditions such as allergic bronchopulmonary aspergillosis/mycosis (ABPA/ABPM). An estimation of the global burden suggested that ABPA develops in approximately five million patients with asthma worldwide. 3 As more time is spent at home in the era of the coronavirus disease 2019 (COVID-19) pandemic, appropriate maintenance of the indoor environment is essential for the health of patients with asthma. However, less is known regarding environmental interventions to reduce indoor molds and their efficacy compared with the approaches for another major indoor allergen, house dust-mites. 4 Mold growth is affected by temperature, relative humidity, and ventilation. Therefore, heating, ventilating, and air-conditioning (HVAC) systems are beneficial for reducing the burden of airborne fungi. 5 However, if not properly maintained, air conditioners themselves can be contaminated with fungi and, consequently, spread fungal spores into indoor air. 6,7 We previously reported a case of ABPM with repeated deterioration due to recurrent exposure to