Table 4.

Summary of the methodology used and of the results found in different datasets focused on detecting SARS-CoV-2 genetic material (RNA), in different community indoor sites.

Reference	Sites	Sampling	Method	Results for air samples	Notes
Conte et al. (2021) Italy	2 supermarket, 1 train station, 1 canteen, 1 commercial centre, 1 pharmacy, 1 hair salon in different cities in north, central, and south Italy.	PM10 sampling at 38.3 L min−1 on quartz fibre filters, volumes 22.9–29.7 m3. TSP sampling at 13.4 L min−1 and at 61.7 L min−1 on quartz filters, volumes 6.2–9.3 m3.	RT-PCR targeting RdRp, N, E genes. dd-PCR targeting RdRp and RNAse P genes.	All of 56 PM10 samples tested negative. All of 13 TSP samples tested negative.	LOD 1.3 copies m−3 for PM10 and 4 copies m−3 for TSP. Recovery 54%.
de Rooij et al. (2021a) Netherlands	Measurements taken inside different mink farms	Sampling of inhalable dust (at 3.5 L min−1) on Teflon filters. Volume 1.26 m3.	RT-qPCR targeting E gene.	3/27 air samples positive. Conc. 2400–4900 copies m−3.	LOD 10–28 copies m−3. Recovery not reported.
de Rooij et al. (2021b) Netherlands	Measurements in a meat processing plant experiencing COVID-19 clusters.	Inhalable dust sampled on Teflon filters at 3.5 L min−1. Volume 1.266 m3.	RT-qPCR targeting RdRp and E genes.	All of 14 air samples tested negative.	LOD 3.2 copies/reaction. Recovery not reported. 6/203 surface samples positive.
Di Carlo et al. (2020) Italy	A bus operating in Chieti (central Italy) in May 2020.	Sampler (AMS Analitica) on gelatine filters at 24 L min−1. Volume 18.72 m3.	RT-PCR targeting ORF1ab, N, S genes.	All of 14 air samples tested negative.	LOD and recovery not reported. 0/90 surface samples positive.
Habibi et al. (2021) Kuwait	Samples in different indoors at the Kuwait Institute of Research.	Sampling at 30 L min-1 in wash bottles with TRIzol (APB Bioscience). Volume 3.6 m3.	RT-qPCR targeting ORF1ab, N genes.	All of 5 air samples tested negative.	Recovery not reported.
Hadei et al. (2021) Iran	Public sites in Theran: 3 banks, shopping centres, post office and a governmental building, airport, subway station and train, bus.	One TSP AV100 sampler at 40 L min-1 on PTFE filters, volumes 1.27–3.5 m3. A SKC pump at 3.5 L min−1 for bus and train sampling, volumes 0.2–0.24 m3.	RT-PCR targeting ORF1ab and N genes.	18/28 air samples positive.	Recovery 20%.
Moreno et al. (2021) Spain	Subway trains and buses in Barcelona.	PM2.5 sampler at 10 L min−1 on Teflon filters. Volumes 5.2–6.3 m3.	RT-qPCR targeting RNA polymerase (IP2, IP4) and N genes.	2/6 subway air samples positive. Conc. 18.8–23.4 copies m−3. 1/6 bus air samples positive. Conc. 1.44 copies m−3.	6/15 surface samples in subway positive. 13/30 surface samples in buses positive.
Viegas et al. (2021) Portugal	Ten higher education facility in Lisbon area.	Coriolis μ sampler at 300 L min−1 on 5 mL vial with buffer NVL. Volume 0.6 m3.	RT-PCR not reported the targets.	All of 48 air samples tested negative.	LOD and recovery not reported. 0/106 surface sample positive.
Xie et al. (2020) China	2 houses with confirmed Covid-19 patients in a residential building in Guangzhou.	Not specified details of the sampling approach used.	RT-PCR not clear the target genes.	All of 3 air samples tested negative.	LOD and recovery not reported. 1/31 surface sample positive (door handle).
Yamagishi et al. (2020) Japan	7 cabins of the Diamond Princess cruise ship.	2 MD8 samplers at 50 L min-1 on gelatine filters. Volume 1 m3.	rRT-PCR not clear the target genes.	All of 14 air samples tested negative.	LOD and recovery not reported. 58/587 surface samples positive.