Assessment of indoor biological air quality at a mass gathering event in an unimproved exhibition facility during the COVID-19 pandemic using a novel air sampling technology

ABSTRACT The objective was to evaluate the determination of biomarkers of air quality during a mass gathering event at a convention center using a novel air sampling device, AirAnswers®. This sampler has previously only been used in smaller locations. Here it was run at five crowded locations within the exhibit area for the four days duration of a trade show. The AirAnswers® device uses electro-kinetic flow to sample air at high rates and capture bio-aerosols on grounded electrodes in assayable form. Cartridges were removed from the devices and immediately conveyed to the Inspirotec facility in North Chicago, where assays were performed. Biomarkers determined were for allergens and molds previously described for this system. Testing for a new marker, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA was also included. The method was validated by determination of capture efficiency with reference to an impinger sampler in a Class III controlled environment chamber. Average capture efficiency for triplicate runs was 14%. One SARS-CoV-2 positive sample as found at the registration area, which was physically separate from the main exhibit area. Cat allergen Fel d 1was found in four of the locations, dog allergen Can f 1 at two. The airborne biomarker of mold proliferation, (1→3)-β-D-Glucan, was above the assay range in all locations. The widespread presence of this mold marker could be accounted for by signs of water leakage. A generic 18S RNA marker for mold was developed and similarly showed the presence of mold in all locations, as was a genus marker for penicillium . A species marker for Cladosporium cladosporioides was in two locations. Species markers for Eurotium amstelodami and Trichoderma viride were each in a single location. The main findings were of the widespread presence of mold markers, and the sporadic appearance of SARS-CoV-2. Masking was recommended but not enforced.