Table 3.

Summary of the methodology used and of the results found in different datasets focused on detecting SARS-CoV-2 genetic material (RNA), with quantification of concentrations in indoor sites in hospitals and healthcare setting in which were present COVID-19 patients.

Reference	Sites	Sampling	Method	Results for air samples	Notes
Chia et al. (2020) Singapore	3 AIIRs in the ICU and 27 AIIRS in the wards of a hospital.	6 NIOSH BC251 bioaerosol samplers at 3.5 L min−1. Volume 5.04 m3.	RT-PCR targeting E, ORF1ab genes.	4/10 air samples positive, D > 1 μm. Conc. 916–2000 copies m−3.	Recovery not reported. 56/245 surface samples positive.
Dumont-Leblond et al. (2020), Canada	Acute care hospital rooms in Quebec.	Two plastic IOM (SKC) samplers with gelatine or polycarbonate filters at 10 L min−1. SASS 3100 dry sampler at 300 L min−1. Volumes 2.4–10.8 m3.	RT-qPCR targeting ORF1b gene.	11/100 air samples positive. Conc. 10–514 copies m−3.	Recovery not reported.
Feng et al. (2021) China	Hospital in Zhejiang.	NIOSH sampler at 3.5 L min−1 at 0.2 m from the bed of patients (head position). Volume 0.105 m3.	RT-qPCR but not clear the gene target.	1/12 air sample positive. Conc. 1857 copies m−3.	Recovery not reported. 4/202 surface samples positive.
Guo et al. (2020) China	Hospital: intensive care unit (ICU) and a general COVID-19 Ward in Wuhuan.	Samples collected with SASS 2300 wetted cyclone sampler at 300 L min−1 on viral transport medium. Volume 9 m3.	qRT-PCR targeting ORF1ab, N genes.	4/81 positive in ICU. 0/38 positive in general ward. Conc. 520–3800 copies m−3.	Recovery not reported. 23/161 surface positive in ICU. 2/134 surface positive in general ward.
Habibi et al. (2021) Kuwait	Three major hospitals in Kuwait dealing with Covid-19 patients.	Sampling at 30 L min-1 in wash bottles with TRIzol (APB Bioscience). Volume 3.6 m3.	RT-qPCR targeting ORF1ab, N genes.	5/13 air samples positive. Conc. 12–99 copies m−3.	Recovery not reported.
Hu et al. (2020) China	Various sites in different health facilities of Wuhan.	Centrifugal sampler WA-400 at 400 L min−1 in PBS. Volumes 12 m3.	qRT-PCR targeting ORF1ab gene.	9/81 air samples positive. Conc. 1110–11,200 copies m−3.	Recovery not reported. Virus cultures were negative.
Lednicky et al. (2020a) USA	Student health care centre in Florida for Covid-19 patients.	VIVAS sampler on PBS at 6.5 L min−1. Volume 0.39 m3.	RT-PCR targeting N gene.	1/2 air sample positive. Conc. 870 copies m−3.	LOD 37.5 copies μL−1. Recovery not reported. Virus cultures were negative.
Lednicky et al. (2020b) USA	A two patient room in a hospital in Florida with 6 air exch. h−1.	VIVAS sampler and a BioSpot-VIVAS BSS300P on PBS at 8 L min−1. Volume 1.44 m3.	RT-PCR targeting N gene.	4/4 air samples positive. Conc. 1600–94,000 copies m−3.	LOD 37.5 copies μL−1 (liquid phase). Recovery not reported. One sample showed positive virus culture.
Liu et al. (2020) China	Different sites in three hospitals of Wuhuan.	TSP sampled on gelatine substrate at 5 L min−1. 3 size-segregated samples. Volumes 1.5–5 m3.	dd-PCR targeting Orf1ab and N genes.	16/25 samples positive. Conc. 1–42 copies m−3.	Recovery not reported.
Moore et al. (2021) UK	8 hospitals, different locations (11 AIIRS), 11 neutral pressure side rooms, six ICU/HDU, open cohorts and 12 non-ICU sites.	Coriolis sampler at 300 L min−1 in PBS and a MD8 sampler in gelatine filters at 50 L min−1. Volumes 0.5–3 m3. <1 m from patients.	qRT-PCR targeting N gene.	4/55 samples positive with Coriolis sampler. 0/34 samples positive with MD8 Conc. 10–460 copies m−3.	Recovery not reported. 30/336 surface samples positive. Virus cultures were negative.
Ong et al. (2021) Singapore	AIIRs and a community isolation facility (CIF).	Samples using a BioSpot-VIVAS BSS300-P at 8 L min-1 not clear sampling time.	qRT-PCR targeting E, ORF1ab genes.	6/12 positive samples in AIIRs conc. 179–2738 copies m−3. 1/9 positive sample in CIF, conc. 978 copies m−3.	Recovery not reported.
Passos et al. (2021) Brazil	2 hospitals in the area of Belo Horizonte.	Different low and high volume samplers on cellulose, quartz, and PTFE filters. Volumes 0.12–250 m3.	RT-PCR targeting N1 and N2 genes.	3/33 samples positive. Conc. 0.14–0.33 copies m−3.	Recovery ~100% 0/5 surface samples positive.
Santarpia et al. (2020) USA	Rooms and hallways of quarantine and isolation care areas in Nebraska.	MD8 sampler on gelatine filters at 50 L min−1. Volume 0.75 m3.	RT-PCR targeting E gene.	12/19 samples in rooms positive. Conc. 2420–8340 copies m-3. 14/24 hallway samples positive. Conc. 2080–8690 copies m−3.	LOD 5 copies μL−1 (liquid phase). Recovery not reported. 60/74 surface samples positive. Cultivation of virus was tried but not confirmed.
Stern et al. (2021a) USA	Different sites at a hospital in Boston.	Cascade impactor, 3 stages (<2.5 μm, 2.5–10 μm, >10 μm) using polyurethane foam and glass fibre filters (for PM2.5) at 5 L min−1, volume 14.4 m3.	RT-qPCR targeting N gene.	8/90 air samples positive. Conc. 5–51 copies m-3.	Recovery not reported. Positive samples span all size fraction.
Stern et al. (2021b) Kuwait	A Covid-19 hospital and a temporary quarantine facility (TQF).	Cascade impactor, 3 stages (<2.5 μm, 2.5–10 μm, >10 μm) using polyurethane foam and glass fibre filters (for PM2.5) at 5 L min−1, volume 14.4 m3.	RT-qPCR targeting N gene.	8/98 air samples positive in hospital. Conc. 8–25 copies m−3. 0/39 air samples positive at TQF.	Recovery not reported. Positive samples span all size fraction.
Zhou et al. (2020a) UK	7 clinical areas (Covid-19), a public area of hospital in London.	Coriolis sampler in 5 mL DMEM, volume 1 m3.	RT-PCR targeting E gene.	2/31 samples positive. Conc. 404–7048 copies m−3.	Recovery not reported. 23/218 surface samples positive.
Zhou et al. (2021a) China	4 hospitals with natural ventilation in Wuhan.	Air-nCOV-Watch samplers (impingers) at 15 L min-1 and 400 L min-1 on virus sampling liquid. Volumes 0.6–16 m3.	RT-PCR targeting ORF1ab, N genes and dd-PCR.	3/44 air samples positive. Conc. 9–219 copies m−3.	Recovery not reported. 10/318 surface samples positive.