Table 2 Summary of sampling parameters, molecular analysis methods, and results on the detection, quantification, and viability of SARS-CoV-2 RNA in air samples

Cai et al.⁸²

Dry-filter air sampler

12 m³ **

1 h

200 L/min

Electret filters (5 mm)

Stored at −20°C and analysed within 3 days of collection

Not mentioned

Not reported

ORF1ab

Ct ≤ 38

Not clear

0% (0/15)

No quantification

Not studied

Cheng et al.⁸³

Sartorious MD8

1 m³

20 min

50 L/min

Gelatine (80 mm) filter

Not clear

Not mentioned

Not reported

RdRp

Not clear

Not clear

0% (0/6)

No quantification

Not studied

Chia et al.⁸⁴

NIOSH connected to either SKC AirCheck TOUCH Pumps or SKC pumps. SKC 37 mm cassettes connected to SKC pumps

5.04 m³ (NIOSH) and 1.2 m³ (cassettes)

4 h

3.5 L/min (NIOSH) and 5 L/min (cassettes)

PTFE (37 mm) filter *

Storage at 4 °C, transport to the analysis laboratory, pretreatment and storage at -80 °C

Not mentioned

Not reported

E and ORF1ab

Amplification in at least one assay

Not clear

0% (0/4). Detection in other matrices that are not filters.

No quantification

Not studied

Conway-Morris et al.⁸⁵

(NIOSH) BC 251 2-stage cyclone aerosol samplers. Samplers ≥2 m from patients.

1.26 m³

6 h

3.5 L/min

PTFE (37 mm) filter *

Pretreatment of samples and storage at -80 °C

Not mentioned

Not reported

Not clear

Not clear

Not clear

0% (0/73). Detection in other matrices that are not filters.

No quantification

Not studied

Declementi et al.⁸⁶

SKC Flite pumps

5.1 m³ **

340 min

15 L/min

PTFE (47 mm) filter

Transfer of the samples to 4 °C and analysis in the subsequent 3 h

Not mentioned

Not reported

Not clear

Not clear

Not clear

0% (0/8)

No quantification

Not studied

Kim et al.⁸⁷

MD8 Airport Portable Air Sampler (Sartorius). Air was sampled 2 m from the patient

1 m³

20 min **

50 L/min

Gelatine filter

Not clear

Not mentioned

Not reported

RdRp and E

Ct ≤ 35 (positive); Ct > 40 (negative); Ct 35–40 (Indeterminate).

Not clear

0% (0/52)

No quantification

Not studied

Lane et al.⁸⁸

NIOSH connected a PCXR-4, SKC pump. 102-152 cm above the floor

1.26 m³ **

6 h

3.5 L/min

PTFE (37 mm) filter *

Storage at −80 °C

Not mentioned

Not reported

(N1, N2, N3) or (N1, E)

Ct < 40

10 viral copies/mL

0% (0/176)

No quantification

Not studied

Lei et al.⁸⁹

A two-stage cyclonic bioaerosol sampler NIOSH. The equipment is placed at a height of 1.3 m and 1 m from the patient

0.84 m³ **

4 h

3.5 L/min

PTFE filter *

Not clear

Temperature, relative humidity, and CO₂

Not reported

Orf1 and N

Not clear

Not clear

0%, the number of filter samples is not clear. Detection in other matrices that are not filters.

No quantification

Not studied

Moore et al.⁹⁰

MD8 air sampler. Samplers located near to patients ( < 1 m)

0,5 m³

10 min

50 L/min

Gelatine filter *

Storage at −80 °C

Temperature and relative humidity

Not reported

RdRp, E, N, Orf1ab

Sample positive: both replicates amplified. “Suspect”: one replicate amplified.

Not clear

0% (0/34). Detection in other matrices that are not filters.

No quantification in filters. Quantification in other matrices that are not filters

Not studied

Morioka et al.⁹¹

MD8 airscan sampling device (Sartorius)

1 m³ **

20 min

50 L/min

Gelatine (80 mm) filter

Pretreatment after sample collection. Storage −80 °C until extraction.

Not mentioned

Not reported

N

Not clear

Not clear

0% (0/4)

No quantification

Not studied

Nakamura et al.⁹²

MD8 airscan (Sartorius). Samplers on the floor about 1.5–2 m from the patient’s head.

1 m³ **

20 min

50 L/min

Gelatine (80 mm) filter

Pretreatment after sample collection. Storage −80 °C until extraction.

Not mentioned

Not reported

N

Not clear

Not clear

0% (0/11)

No quantification

Not studied

Ong et al.⁹³

SKC Universal pumps (with 37-mm filter cassettes) in the room and a Sartorius MD8 microbiological sampler outside the room

1.2 m³ (SKC) and 1.5 m³ (MD8) **

4 h (SKC) and 15 min (MD8)

5 L/min (SKC) and 100 L/min (MD8)

PTFE (37 mm) filter (SKC) and gelatine filter (MD8)

Storage at −80 °C until PCR

Not mentioned

Not reported

E

Strong positive: low Ct ( ≤ 32). Weak positive: high Ct ( > 32).

Not clear

0% (0/5)

No quantification

Not studied

Perrone et al.⁹⁴

ACD-200 Bobcat dry-filter air sampler

Not clear

Not clear

200 L/min

Dry electret filter (52 mm)

Analysis hours after collection

Not mentioned

Not reported

Not clear

Not clear

Not clear

0% (0/17)

No quantification

Not studied

Song et al.⁹⁵

Derenda PNS 16T-3.1 (automatic sampling system)

1.5 m³ **

1.5 h

16,7 L/min

Membrane filter (46 mm)

Storage −80 °C until extraction.

Not mentioned

Not reported

RdRp and N

Not clear

Not clear

0% (0/42)

No quantification

Not studied

Zhang et al.⁹⁶

Air Virus collection equipment (NingBo iGene TecTM)

1 m³ **

10 min

100 L/min

Gelatine filter

Samples analysed within 24 hours of collection

Not mentioned

Not reported

ORF1ab

Ct ≤ 38

LoD 100 copies/mL

0% (0/24)

No quantification

Not studied

Ang et al.²⁵

SASS 3100 air samplers. 0.9–3 m of distance to the patient

24 and 72 m³ **

8 h

50 and 150 L/min

SASS bioaerosol filter (polyester) (44 mm)

Storage at −80 °C

Not mentioned

Not reported

E and N

Not clear

1.3-2.2 copies/m³

72% (13/18)

No quantification

Not show conclusive evidence for successful viral culture.

Baboli et al.²⁶

SKC universal air sampling pumps. 1–3 m from patient beds. The samplers operated at a height of 1.5 to 1.8 m above the ground.

0.12 m³ **

30 min

4 L/min

PTFE (37 mm) filter

Stored at 4 °C until arrival at the analysis laboratory and then frozen at −70 °C until extraction.

Temperature and relative humidity

Not reported

RdRp and N

Ct ≤ 40

Not clear

22% (2/9)

No quantification

Not studied

Barbieri et al.²⁷

SILENT air sampler.

14.4 m³

24 h

10 L/min

Quartz filter

Not clear

Not mentioned

Not reported

RdRp

Ct < 40

Not clear

80% (4/5), positive in at least one replicate

No quantification

Not studied

Bazzazpour et al.²⁸

AV1000 air sampler (collects PM2.5). Positioned 1–2 m above floor, 0.8–2 m from individuals.

2.9-5.9 m³

1-2 h

30-58 L/min

PTFE (90 mm) filter

Transport to the laboratory at 4 °C. Pretreatment of samples and storage at −80 °C

Temperature, relative humidity and other records

Infectious ronchitis virus (IBV) for extraction efficiency (Recovery 25%)

N and ORF1ab

Not clear

Not clear

36% (13/36)

No quantification

Not studied

Ben-Shmuel et al.²⁹

MD8 air sampler (Sartorius)

1 m³

20 min

50 L/min

Gelatine filter

Samples were transported at 4–8 °C and processed within 2–3 hours of collection.

Not mentioned

Not reported

E

Not clear

Not clear

38% (3/8)

No quantification

No viable virus was recovered from any of the samples in Vero-E6 cell cultures.

Binder et al.³⁰

NIOSH sampler. 1.5 m from the ground; 1-3.2 m from the patient’s head.

0.84 m³

4 h

3.5 L/min

PTFE filter *

Not clear

Not mentioned

Not reported

N1 and N2

Ct < 40 (positive for two genes)

3.31 (N1) and 2.93 (N2) copies/reaction

2% (3/195)

No quantification

The culture of the virus in cells from the positive air samples was negative

Dubey et al.³¹

Total suspended particulate (TSP) air sampler. 1–3 m distance from patients.

0.9, 1 and 1.62 m³ **

1 h

1.5, 16.7 and 27 L/min

PVDF (47 mm) filter

Not clear

Not mentioned

Not reported

E and RdRp

Ct < 35 for two genes

Not clear

43% (17/126)

No quantification

Not studied

Ge et al.³²

NIOSH bioaerosol sampler (BC251) with air pumps (XR5000, SKC)

0.105 m³ **

30 min

3.5 L/min

Not clear

Transport on ice to laboratory

Not mentioned

Not reported

N

Ct < 40

Not clear

9% (1/11)

No quantification

Not studied

Ghaffari et al.³³

ESPS LVM Model (Fanpava)

24.04 m³

24 h

16.7 L/min

PTFE filter

Transport to the laboratory at 4 °C. Storage at −80 °C

Temperature, relative humidity, PM2.5, PM10 and TSP

Not reported

N and RdRp

Not clear

Not clear

13% (2/16)

No quantification

Not studied

Gohli et al.³⁴

SASS 3100 samplers. Inlet at face level, 45° downward. Positioned 1, 2, and 4 m from subjects

4.5 m³

15 min

300 L/min

Electret filters

Transported to the laboratory in ice bags and stored at -80 °C until further processing

Not mentioned

Not reported

RdRp and ORF1b

Ct < 45

2.2 copies /L of air (LoD)

22% (19/87)

No quantification

The cell culture assay was negative for all samples.

Hadavi et al.³⁵

SKC personal sampling pumps: cassette filter holder. Height: 1.5 m, distance: 1.5–2 m from patient bed

1.5 m³

1 h

25 L/min

PTFE (47 mm) filter

Stored at 4 °C until arrival at the laboratory and then frozen at -30 °C until extraction

Not mentioned

Not reported

RdRp and S

Not clear

Not clear

9% (2/23)

No quantification

Not studied

Huang et al.³⁶

A Sartorius AirPort MD8 air sampler

1 m³

20 min

50 L/min

Gelatine (80 mm) filter

Not clear

Not mentioned

Not reported

Not clear

Not clear

LoD: 10 copies/ml in gelatin suspension

2% (19/838)

No quantification

Not studied

Kotwa et al.³⁷

GilAir Plus personal pump: 3-piece cassette and NIOSH. Positioned 1 m and 2 m from patient head

0.42 m³ **

2 h

3.5 L/min

PTFE (37 mm), polycarbonate (37 mm) and gelatine (25 mm) filters

Transport in coolers. Pretreatment after sample collection. Storage -80 °C until extraction.

Not mentioned

Not reported

E and UTR

Ct < 40

Not clear

2% (3/146)

No quantification

Virus cultures negative for air

Lane et al. (2)³⁸

NIOSH sampler. 1-1.5 m from the ground; 0.3-3 m from the patient’s head

1.26 m³ **

6 h

3.5 L/min

PTFE (37 mm) filter *

Storage at -80 °C

Not mentioned

Not reported

(N1, N2) or (N2, E)

Ct < 40

1-5 copies/µL

1% (1/192)

No quantification

Not studied

López et al.³⁹

A vacuum pump was used

1.73 m³ **

3 h

9.6 L/min

Not clear

Not clear

Not mentioned

Not reported

E

Not clear

Not clear

30% (3/10)

No quantification

Not studied

Mouchtourri et al.⁴⁰

Sartorius Airport MD8

0.5 m³

10 min

50 L/min

Gelatine (80 mm) filter

Not clear

Not mentioned

Not reported

Not clear

Not clear

Not clear

8% (1/12)

No quantification

Not studied

Nissen et al.⁴¹

HEPA filters of the ventilation system. 3 filter samples (3 × 3 cm) were randomly cut with sterilized scissors

Not clear

Not clear

Ventilation airflow: 2.27–3.48 m³/s

HEPA filter

Storage at 4 °C until analysis up to 72 hours later

Not mentioned

Not reported

N and E

Not clear

Not clear

62% (8/13)

No quantification

No significant Potential cytopathic effect (CPE)

Razzini et al.⁴²

MD8 Airport Portable Air Sampler. 1.5 m above the floor

2 m³

40 min

50 L/min

Gelatine filter

Transport between 2 and 8 °C to the laboratory

Not mentioned

Not reported

Not clear

Ct < 38

Not clear

40% (2/5)

No quantification

Not studied

Sousan et al.⁴³

Filter cassettes (SKC), Button sampler (SKC) and AerosolSense sampler (ThermoFisher Scientific)

7.2 m³ (Filter cassetes); 5.76 m³ (Button); 288 m³(AerosolSense) **

24 h

5 L/min (Filter cassetes); 4 L/min (Button); 200 L/min (AerosolSense)

PTFE, PVC and gelatine filters *

Storage at -20 °C and analysis in 10 days

Not mentioned

Not reported

N1 and N2

Not clear

Not clear

7% (11/163)

No quantification

Not studied

Stern et al.⁴⁴

Cascade impactor: 3 sizes: >10.0 μm, 2.5–10.0 μm, <2.5 μm. Inlets at breathing-zone height

Not clear

72 h

Not clear

Not clear

Not clear

Not mentioned

Not reported

N1 and N2

Ct ≤ 40

Not clear

6% (31/510)

No quantification

Not studied

Tan et al.⁴⁵

The air samplers were placed less than one meter from the patient’s head and in clean areas

0.3 m³ **

1 h

5 L/min

Membrane filter

Samples were immediately transported on ice to the laboratory for analysis

Not mentioned

Not reported

ORF1ab

Not clear

Not clear

3% (1/29)

No quantification

Not studied

Amato-Lourenço et al.⁴⁶

MiniVol sampler (Air Metrics). The samplings were carried out at a height of 1.25 m

2.4 m³ **

8 h

5 L/min

Polycarbonate (47 mm) filter

Storage at -20 °C

Temperature and relative humidity

Not reported

N and E

Ct < 40

Not clear

E: 73% (24/33), N: 15% (5/33)

E: 1,294-262,500 genomic units/m³, N: 12.45-718.83

Not studied

Barberá-Riera et al.⁴⁷

Derenda

55 m³

24 h

38 L/min

Quartz (47 mm) filter

Stored at −20 °C until analysis

Temperature, relative humidity and CO₂

Mengovirus for extraction efficiency (Recovery 51% ± 22%)

N1, N2 and E

Ct < 40 (at least 1 positive of 3 target genes)

Not clear

11% (5/44)

1.9-13.5 gc/m³

Not studied

Feng et al.⁴⁸

NIOSH. heigh 1,2 m. 2 m away the bed

0.105 m³

30 min

3.5 L/min

PTFE filter *

Not clear

Not mentioned

Not reported

Not clear

Ct < 40

Not clear

8% (1/12)

1,112 copies/m³

Not studied

Gregorio et al.⁴⁹

A small vacuum pump connected to a 37 mmdisposable cassette. Sampler positioned at a height of 1.2 m

0.6, 2.4 and 4.8 m³ **

2 h, 8 h and 16 h

5 L/min

PTFE (37 mm) filter

Not clear

Temperature, relative humidity, CO₂, total volatile organic compounds and particulate matter (PM_1.0, PM_2.5 and PM₁₀)

Not reported

N1 and N3

Ct < 38

Not clear

30% (9/30)

6,800-285,000 copies/m³

Not studied

Groma et al.⁵⁰

An in-house built May-type cascade impactor

9.6 m³

8 h

20 L/min

Gelatine filter

Analysis of samples between 12 and 72 h after filter collection

Not mentioned

Not reported

N2

Not clear

LoQ 10 copies/sample (1.04 copies/m³)

36% (90/252)

0.9-184 copies/m³

Not studied

Horve et al.⁵¹

Air handling units filters (ventilation ducts). Samples were collected using swabs on an air filter

Not clear

Not clear

Not clear

Not clear

Not clear

Not mentioned

Not reported

S

Not clear

LoD of 2.22 gene copies/µL

25% (14/56)

3.2-49 copies/µL of reaction

Not studied

Nor et al.⁵²

Low Volumen Sampler (LVS) (MINIVOL)

14.4 m³ **

48 h

5 L/min

Glass microfiber filter

Storage at -80 °C

PM2.5

Not reported

N1

Not clear

Not clear

50% (2/4)

10-74 copies/µL

Not studied

Oksanen et al.⁵³

3 sampling equipment by filter-based or impaction: 1. A Dekati PM10 cascade impactor (model PMS-420); 2. A sampler Button with a Gilian 5000 air sampling pump; 3. A Dekati eFilter

3,6 m³ (Dekati), 0.09 m³ (Button) and 0.85 m³ (eFilter) **

2-4 h (Dekati), 13-31 min (Button) and 30 min (eFilter)

20 L/min (Dekati), 4 L/min min (Button) and 28.3 L/min (eFilter)

Cellulose acetate membrane (25 mm) and 40-mm filter for the backup (Dekati); gelatine or mixed cellulose ester (MCE) (25 mm) (Button); gelatine (47 mm) filter (eFilter) *

Not clear

PM

Not reported

N1

Results positive: both qRT-PCR < 40 Ct, or one qRT-PCR < 38 Ct.

between 5 and 50 copies/reaction for N1 gene

9% (5/55)

1.04 × 10³ -2.05 × 10⁷ copies/ml of sample

All air samples were cultured, but no viable viruses were observed.

Santarpia et al.⁵⁴

Sartorius Airport MD8 sampler. Additional personal air samples were collected using SKC button samplers and Air Chek pumps. At least 1 meter from the patient

0.75 m³

15 min (MD8)

50 L/min (MD8) and 4 L/min (personal air samples)

Gelatine filter (80 mm for MD8 and 25 mm for personal air samples)

Not clear

Not mentioned

Not reported

E

Not clear

Minimum detection: 1e¯¹ copies/µL, 39–44 cycles.

66% (23/35)

2,080-48,220 copies/m³

Infectivity: extremely low. Virus culture not confirmed due to low concentrations.

Santarpia et al.⁵⁵

NIOSH BC251 sampler

0.105 m³ **

30 min

3.5 L/min

Gelatine (37 mm) filter *

Not clear

Aerosol concentrations and size distributions

Not reported

E

Not clear

Not clear

100% (6/6)

1.01× 10⁶ -9.69× 10⁶ copies/m³

3 samples out of 18 showed viral growth in cells.

Stein et al.⁵⁶

3 sampling equipment: 1. An AerosolSense 2900 sampler; 2. BC-251 (NIOSH) 2-stage cyclone samplers with vacuum supplied by an Airchek pump (Model 224-44XR, SKC); 3. Button Samplers (SKC) with vacuum supplied by an Airchek XR5000 pump (SKC)

0.63 m³–1,440 m³

3.5 h–120 h

200 L/min (AerosolSense); 3 L/min (BC-251); 5 L/min (Button)

Gelatine (25 mm) filter

Not clear

Not mentioned

Not reported

E

Ct < 39

Minimum detectable concentration: 1241 copies/mL

13% (7/53)

2-17,140 copies/m³

Not studied

Stern et al.⁵⁷

Micro-environmental cascade impactor of own design. Located 48 to 56 inches above the floor

14 m³

48 h

5 L/min

Polyurethane foam impaction substrates (large and coarse particles) and glass fiber (37 mm) filter (fine particles)

Sending samples on ice to the laboratory for analysis

Not mentioned

Not reported

N

Ct < 40.85 (corresponded to one copy number)

Not clear

9% (8/90)

5-51 copies/m³

Not studied

Young et al.⁵⁸

Ultrasonic personal aerosol samplers

0.96 m³ **

8 h

2 L/m

PTFE (37 mm) filter

Filters were frozen at -80 °C for 1–5 months prior to processing

Not mentioned

Not reported

N1

Ct < 38

LoD: 536 (N1), 443 (N2) and 63 (E) copies

4% (14/336)

66-212,429 gc/m³

Not studied

Conte et al.¹⁰¹

An automatic sequential low-volume sampler (Skypost PM-TCR Tecora), a low-volume sampler (Zambelli Explorer pump) and an in-house built manual TSP sampler operating at low-volume

6.2-29.7 m³

12 h

38.3 L/min (Skypost PM-TCR Tecora), 61.7 L/min (Zambelli Explorer pump) and 13.4 L/min (in-house built manual TSP sampler)

Quartz (47 mm) filter

Storage at -25 °C or -80 °C

Not mentioned

Mengovirus for extraction efficiency (Recovery 54% ± 13%)

RdRp, N and E

Ct ≤ 40 for at least one gene (RdRp or N)

2 copies/μl for all genes (RT-PCR) and 0.58 copies/μL (ddPCR)

0% (0/69)

No quantification

Not studied

de Man et al.⁵⁹

A Nilfisk household vacuum cleaner which has a high-efficiency particulate air (HEPA) filter on the air outlet. Air sampling in homes was done 10 cm from the mouth. Air sampling in UCI was done 50 cm from patients

1.21 m³ **

2.5 min

483 L/min

Surgical face mask was used as a sample filter

Not clear

Not mentioned

Not reported

E and RdRp

Not clear

Not clear

Healthcare settings: 24% (4/17) (hospital); residential: 71% (29/41)

No quantification

Not studied

Moharir et al.⁶⁰

AirPort MD8 air sampler (Sartorius)

1 m³

20 min

50 L/min

Gelatine filter

Not clear

Not mentioned

Not reported

E, N and ORF1ab

Not clear

Not clear

Healthcare settings: 38% (30/80) (hospital); residential: 43% (15/35)

No quantification

A positive virus culture was established in 1 of the 3 samples that were analysed

Habibi et al.⁶¹

The samples were collected using a custom-made sampling device

3.6 m³

2 h

30 L/min

Not clear

Not clear

Not mentioned

Not reported

Not clear

Not clear

Not clear

Healthcare settings: 46% (6/13) (hospitals); Educational settings: 0% (0/2) (institute for Scientific Research)

Healthcare settings: 12-98 copies/m³ (hospitals)

Not studied

Kušan et al.⁶²

NanoMOUDI R122 cascade impactor

 m³ **

2-7 days

30 L/min

Aluminium foils

Immediate analysis upon receipt of samples

Not mentioned

Not reported

Orf1 and S

Ct < 40

Not clear

Healthcare settings: 48% (74/154) (hospital); Residential: 14% (2/14)

Healthcare settings: 0.1-9.5 copies/m³ (hospital); Residential: 0.12-0.56 copies/m³

Not studied

Alfaro et al.⁵

Derenda low volume samplers (PM2.5 inlet): samplers at 1 m above ground, away from doors, windows, and ventilation units.

55,2 m³

24 h

38.3 L/min

Quartz (47 mm) filter

The filters were stored at −2 °C until analysis

Not mentioned

Mengovirus for extraction efficiency (Recovery 58% ± 38%)

N1, N2, E

Ct < 40 (at least one positive of the three target genes)

LoD and LoQ for N1, N2, and E was 2.70 gc/m³, 5.41 gc/m³, and 2.70 gc/m³, respectively.

Healthcare settings: 9% (20/139); socio-health settings: 15% (13/85); educational settings: 4% (11/273)

Healthcare settings: 4.3-504 gc/m³; socio-health settings: 5.4-77 gc/m³; educational settings: 3.1-14 gc/m³

Not studied

Mallach et al.⁶³

Ultrasonic Personal Air Samplers (UPAS)

1.92 m³

16 h

2 L/min

Gelatine filter *

Storage at 4 °C until analysis

Not mentioned

Not reported

E and N

Samples with Ct <36: RNA positive. Ct >36: positive if E and N genes ≤40. E protein concentrations more reliable than N protein.

Not clear

Healthcare settings: 9% (9/95) (hospital); Socio-health settings: 20% (3/15) (long-term care rooms); Other indoor settings: 13% (1/8) (prisons)

Healthcare settings: 64–288 copies/m³ (hospital); Socio-health settings: 93–11,940 copies/m³ (long-term care rooms); Other indoor settings: 395 copies/m³ (prisons)

Viable virus after 16 hours of sampling

Barberá-Riera et al.¹⁰

Personal pump Casella Apex2 Plus Air connected to a PALL 1119 polycarbonate in-line filter holder

1.35 m³–5.76 m³

7,5 - 24,7 h

4 L/m (quartz filters) and 2 L/m (PTFE filters)

PTFE (47 mm) and quartz (47 mm) filters

Filters were stored 24 h at 4 °C until analyis

Not mentioned

Mengovirus for extraction efficiency (Recovery 37 ± 23%)

N1, N2 and E

Ct < 40 (at least one positive of the three target genes)

Not clear

Socio-health settings: 79% (11/14); transport settings: 100% (3/3); other indoor settings (residential): 100% (1/1)

Socio-health settings: ND-19,525 gc/m³; transport settings: ND-1,233 gc/m³; other indoor settings (residential): 829-14,642 gc/m³

Not studied

Dumont-Leblond et al.⁹⁷

IOM Multidust sampler (SKC) connected to a portable pump Gillian Air 5. At least 1.5 m above the floor and 2 meters from residents

0.72 m³

4 h

3 L/min

Gelatine filter

Filters were eluted on the day of sampling and stored at −80 ˚C until RNA extraction.

Not mentioned

Not reported

ORF1b

Ct < 40

Not clear

0% (0/31)

No quantification

Viral culture was negative for all samples

Correia et al.⁶⁴

Styrene filter cassette SKC (TSP) connected a Leland Legacy Personal Sample Pump and an AirChek XR5000 Pump. Size segregated aerosol samples were collected using a miniature cascade impactor (Sioutas impactor, SKC)

0,08-11.88 m³

15-1320 min

TSP (5 L/m) and size segregated (9 L/m)

Gelatine (25 or 37 mm) filters

Analysis within 4 h of sample collection

Not mentioned

Not reported

E

Not clear

Not clear

5% (2/37)

No quantification

In the viral viability analyses, the replication of SARS-CoV-2 in the host cells was not confirmed

Linde et al.⁶⁵

NIOSH BC 251 and Conical Inhalable dust Sampler (CIS), both connected to a Gilian GilAir 5 pump. Heigh 1,5 m

1.26 m³

6 h

3.5 L/min

PTFE (37 mm) filter *

Transport at 4 °C to the laboratory. Storage at 4 °C in the laboratory until analysis in 24 h

Not mentioned

Not reported

RdRp and E

Ct < 40 (detection of both genes)

Not clear

20% (2/10)

No quantification

Cytopathic effects were observed in an active air sample, but did not correspond to the smallest fraction (filter)

Di Carlo et al.¹⁰²

Constant flow sampler (AMS Analitica model HE BASIC PLUS)

18.7 m³

6.5 h

24 L/min

Gelatine filter

The samples were sent immediately after collection to the laboratory for analysis

Not mentioned

Not reported

ORF1ab, N and S

Ct < 37 for at least two genes

Not clear

0% (0/14)

No quantification

Not studied

Yamagishi et al.⁹⁸

MD8, Sartorius

1 m³ **

20 min

50 L/min

Gelatine filter

The samples were stored for at least 14 days at -80 °C

Not mentioned

Not reported

Not clear

Not clear

Not clear

0% (0/7)

No quantification

Not studied

Hadei et al.⁶⁶

AV1000 sampler and SKC pump (Universal PCXR4). The samplers were placed at the height of 0.9–1.6 m above the ground

1.27–3.5 m³ (AV1000) and 0.2–0.24 m³ (SKC)

1–1.5 h

40 L/min (AV1000) and 3.5 L/min (SKC)

PTFE (AV1000) and glass fiber (SKC) filters

Transport at 4 °C to the laboratory. Pretreatment of samples and stored at -80°C until analysis.

Temperature

Infectious Bronchitis Virus (IBV) for extraction efficiency. (Recovery 20%)

N and ORF1ab

Not clear

Not clear

Transport settings: 67% (10/15); other indoor settings (residential): 62% (8/13)

No quantification

Not studied

Mortazavi et al.⁶⁷

Sensidyne Gilian BDX-II Abatement air sampling pump with 47 mm filter cassettes

0.027 m³

90 min

0.3 L/min

PTFE (47 mm) filter

Transportation of the samples at 4 °C to the laboratory and then they are analysed

PM1, PM2.5, and PM10

Not reported

Not clear

Not clear

Not clear

10% (3/30)

No quantification

Not studied

Lednicky et al.¹⁷

Sioutas personal cascade impactor sampler (PCIS) with a Leland Legacy (SKC) pump. 3 feet from face

0.14 m³

15 min

9 L/min

PTFE filter

Pretreatment 30 min after sample collection. Storage -80 °C until extraction

Not mentioned

Not reported

N

Not clear

Not clear

80% (4/5)

1.2 × 10³ -7.8 × 10³ genome equivalents/m³

Not studied

Moreno et al.⁶⁸

Personal Environmental Monitor (PEM) with Leland pump equipment

5.2-6.2 m³

9-10 h

10 L/min

PTFE (47 mm) filter

Not clear

Not mentioned

Not reported

IP2, IP4 and E

2–3 positive targets: high virus contamination. 1 positive target: weak contamination

Not clear

25% (3/12)

1.4-23.4 cg/m³

Not studied

Vass et al.⁹⁹

NIOSH bioaerosol samplers (Model BC-251). 1.5 m above the floor

0.54 m³ **

3 h

3 L/min

PTFE (37 mm) filter *

Transport on dry ice and storage at −80 °C

Not mentioned

Not reported

N2

Not clear

Not clear

0% (0/2). Detection in other matrices that are not filters.

No quantification in filters. Quantification in other matrices that are not filters

They observe viable using non–filter-based samplers

Vass et al.¹⁰⁰

NIOSH (BC-251 model) connected a Airheck pump (224-PCXR4)

0.63 m³ **

3 h

3,5 L/min

PTFE (37 mm) filter *

Storage at −80 °C

Temperature and relative humidity

Not reported

N2

Not clear

Not clear

0% (0/22). Detection in other matrices that are not filters.

No quantification in filters. Quantification in other matrices that are not filters

They observe viable virus using non–filter-based samplers

Laumbach et al.⁶⁹

Leland Legacy pump (SKC) with an open-face filter holder

14.4 m³

24 h

10 L/min

PTFE filter

Not clear

Not mentioned

Not reported

N, S and ORF1ab

Ct < 37

Not clear

70% (14/20)

No quantification

Not studied

Shankar et al.⁷⁰

Airchek sampler pump or Escort ELF pump with an inline air sampler that traps particles, a NIOSH 2-stage cyclone sampler (BC-251), and a Sioutas personal cascade impactor sampler with Leland Legacy pump

0.27, 0.36, 0.54 and 0.81 m³

90, 120 and 180 min

3 L/min (Airchek sampler and NIOSH), 9 L/min (Sioutas)

PTFE (25 or 37 mm) filter

Pretreatment 30 min after sampling. Storage −80 °C until extraction

Not mentioned

Not reported

RdRp and N

Not clear

Not clear

31% (5/16)

9.9 × 10⁸- 3× 10¹¹ genome equivalents/m³

Not studied

Del Real et al.⁷¹

Indoor: Personal PM samplers connected to a particle impactor and a cassette for a non-segregated. Portable pump: placed ~1.5 m above ground.Outdoor: A gravimetric air sampler (Dekati PM10 Impactor)

Indoor: 0.71-4.68 m³ Outdoor: 43.2 m³

Indoor: 4-26 h Outdoor: 24 h

Indoor: 3 L/min Outdoor: 30 L/min

Indoor: PTFE filter Outdoor: Polycarbonate and PTFE filters

Pretreatment after sample collection. Storage -80 °C until extraction

Not mentioned

Not reported

N1 and N2

Ct < 40 (when N1 and N2 genes are positive)

The lowest concentration of RNA was 0.04 ng/µL

Healthcare settings: 2% (1/44) (hospital); Educational settings: 0% (0/42) (university); Outdoor: 0% (0/5)

Healthcare settings: 15 ng/μL (hospital); Outdoor: No quantification

Not studied

Passos et al.⁷²

Indoor: Different air samplers: CRIFFER with a styrene filter cassette (SKN); AIRIDEAL 3 P; MD8; 821 T connected to an adapted acrylic collector Outdoor: HANDI-VOL (high-volume); HVS (high-volume)

Indoor: 0.12-800 m³ Outdoor: 7.1-4500 m³

Variable: From a few minutes to over 7 days

Indoor: 2.5 L/min (Criffer); 18 L/min (821 T); 150 L/min (HANDI-VOL) Outdoor: 1130 L/min

Indoor: Gelatine filter (MD8), Cellulose nitrate membrane, PTFE and quartz microfiber filters Outdoor: Quartz filter

Samples sent immediately to the laboratory or refrigerated at 4 °C until receipt in the laboratory.

Temperature, relative humidity and atmospheric pressure

Not reported

N1 and N2

Ct < 40 (positive for two genes)

Not clear

Healthcare settings: 9% (3/33) (hospital); Outdoor: 0% (0/10)

Healthcare settings: 0.14-34.3 genomic units/m³ (hospital); Outdoor: No quantification

Not studied

Grimalt et al.⁷³

Aircheck XR5000 pump (SKC) with a SureSeal Cassette Blanks composed of three 37 mm diameter styrene clear pieces. 1.5 m above ground. In the COVID-19 patient rooms it was located 2 m away from the beds (indoor).

1.08 m³

4 h

4.5 L/min

PTFE (37 mm) filter

Not clear

Not mentioned

The 77b fragment of the Equine Arteritis virus as internal control of the extraction (Recovery 100%)

E

Ct < 44.25

Not clear

Healthcare settings: 72% (31/43) (hospital); Outdoor: 25% (1/4)

Healthcare settings: 700-6200 copies/m³ (hospital); Outdoor: 290 copies/m³

Not studied

Liu et al.⁷⁴

Indoor: Styrene filter cassettes (SKC) with a portable pump (APEX2, Casella) and miniature cascade impactor (Sioutas Impactor, SKC). The sampling inlet: 1.5 m above floor Outdoor: Styrene filter cassettes (SKC) a portable pump (APEX2, Casella).

Indoor: 1.3–10.8 m³ ** Outdoor: 1.5 - 5 m³ **

Indoor: 4.3–20 h Outdoor: 5–16.7 h

Indoor: 5.0 L/min (APEX2, Casella); 9.0 L/min (Sioutas Impactor, SKC) Outdoor: 5 L/min

Gelatine filter

All samples were processed immediately in the laboratory

Not mentioned

Not reported

ORF1ab and N

Not clear

ddPCR LLoD:ORF1ab: 2.18 copies;N: 0.42 copies per 20 µl reaction

Healthcare settings: 64% (16/25) (hospital); Outdoor: 38% (3/8)

Healthcare settings: 1-42 copies/m³ (hospital); Outdoor: <3-11 copies/m³

Not studied

Stern et al. (2)⁷⁵

Custom-designed Harvard Micro-Environmental Cascade Impactors: 3 distinct size fractions: fine ( ≤ 2.5 μm), coarse (2.5–10 μm), and large ( ≥ 10 μm)

14.4 m³

48 h

5 L/min

Polyurethane foam (PUF) substrate (2 first stages) and glass fiber (37 mm) filter (last stage)

Storage at 4 °C and shipping on ice to the analysis laboratory

Not mentioned

Not reported

N

Ct < 39

Not clear

Healthcare settings: 6% (8/125); Outdoor: 10% (5/51)

Healthcare settings: 25 copies/m³ (maximum concentration); Outdoor: 17 copies/m³ (maximum concentration)

Not studied

de Rooij et al.⁷⁶

Indoor: Stationary air sampling (Gilian GilAir 5 pumps) and personal air sampling were conducted for PM10 (PEM sampling heads (MSP 90)). Inhalable dust sampling (GSP, Gesamtstaubprobenahme) Outdoor: Stationary air sampling for PM10. Harvard impactors (Air Diagnostics and Engineering Inc.) and GSP sampling heads connected to a Gilian GilAir 5 pump (Sensidyne)

Indoor: 1.26-1.92 m³ Outdoor: 43-72 m³ (Harvard) and 15-25 m³ (GSP)

Indoor: 6-8 h Outdoor: 3–7 days

Indoor: 3.5 L/min (GSP) and 4 L/min (MSP90) Outdoor: 10 L/min (Harvard) and 3.5 L/min (GSP)

PTFE (37 mm) filter

Transport at 4 °C, stored at -80 °C in the lab, and sent on dry ice to another lab for analysis.

Not mentioned

Not reported

E

Not clear

Not clear

Indoor: 20% (13/66) Outdoor: 15% (11/72)

Indoor: 2,400-4,900 copies/m³ Outdoor: 110-4,800 copies/m³

Viability testing on the two air samples was unsuccessful.

Chirizzi et al.¹⁰³

Low volume aerosol sampler (PM10) (Skypost PM-TCR Tecora and SWAM 5a Dual Channel Monitor-FAI Instruments). Size-segregated samples were collected with a r MOUDI cascade impactor

110 m³ (PM10) and 250 m3 (MOUDI)

48 h (PM10) and 144 h (MOUDI)

38,3 L/min (PM10 samples) and 30 L/min (Size-segregated samples)

Quartz filter

Filters were frozen at -25 °C until analysis up to 4 days.

Not mentioned

Mengovirus for extraction efficiency (Recovery 49 ± 5%)

RdRp and E

Not clear

LoD 10 copies/µL (RT-PCR) and 0,625 copies/µL (ddPCR)

0% (0/60)

No quantification

Not studied

Linillos et al.¹⁰⁴

MCV high volume samplers were collocated with different inlets (Digitel DHA-80) for sampling the PM10, PM2.5 and PM1 specific size fractions

525–720 m³ **

17.5–24 h

500 L/min

Quartz (150 mm) filter

Not clear

Real-time monitoring of PM10 y PM2,5 and PM1. Meteorological parameters were recorded.

Not reported

N1and N2

Ct < 35 for N1 and N2

0% (0/18)

No quantification

Not studied

Pivato et al.¹⁰⁵

PM (PM10, PM2.5) samples were collected with a low-volume sampling

55.2 m³ **

24 h

38.3 L/min

Quartz (47 mm) filter

Samples for up to 6 days at 20°C and then stored at -20 °C until analysis

Filter gravimetry

Synthetic SARS-CoV-2 armored RNA for extraction efficiency (Recovery not mentioned)

N and Orf1b-14nsp

Ct < 40

LoD 1.2 copies/m³

0% (0/44)

No quantification

Not studied

Setti et al.⁷⁷

A low-volume gravimetric air sampler

55 m³

24 h

36.3 L/min

Quartz filter

Not clear

Temperature, relative humidity and irradiance

Not reported

E, N and RdRp

Not clear

Not clear

59% (20/34), for at least one of the three marker genes

No quantification

Not studied

Amato-Lourenço et al. (2)⁷⁸

TSP samples were collected using a Handi-vol sampler. The samplings were carried out at a height of 1.25 m.

4.32 m³ **

24 h

3 L/min

Fibreglass (110 mm) filter

The filters were stored at −20 °C until analysis

Filter gravimetry, weather data, including the temperature (°C) and relative humidity (%), were obtained from the station closest to the sampling points

Not reported

E and N1

Ct < 40

Not clear

E: 58% (22/38); N1: 16% (6/38)

E: 4.3-218 genomic units/TSP; N1: 17-157 genomic units/TSP

Not studied

Kayalar et al.⁷⁹

SKC Filter Pack Sampler, Dichotomous PM Sampler, High Volume Air Sampler, Low Vol Stack Filter Unit, Zambelli PM Sampler and High Vol Cascade Impactor

7.2-1422 m³

24 h

Not clear

Glass fiber, PTFE and nucleopore polycarbonate filters

The filters were stored at −20 °C until analysis

Downloaded air quality data and meteorological data

Not reported

N1 and RdRp

Ct < 37 for two genes

Not clear

10% (20/203)

<0.2-23 copies/m³

Not studied

Pivato et al.⁸⁰

Two sampling devices: a low-volumetric rate (LVR; 23–54 m3/sample) sampler and a high-volumetric rate sampler (HVR)

23-54 m³ (LVR) 248-534 m³ (HVR)

24 h (LVR) and not mentioned for HVR

38.3 L/min (LVR) and not mentioned for HVR

Quartz (47 mm) (LVR) and PTFE (142 mm) (HVR) filters

Samples for up to 6 days at 20°C and then stored at -20 °C until analysis (LVR) and he filters were stored at −20 °C until analysis (HVR)

Meteorological conditions were registered by the weather station closest

Mengovirus for extraction efficiency (Recovery 0.8%)

Orf1b nsp14

Ct < 40

LoD 0.41 gc/µL and LoQ 3,71 gc/µL

63% (24/38)

0.3-4.2 copies/m³

Not studied

Tao et al.⁸¹

Fine particle samples (PM2.5) and coarse particle samples (PM10) were collected using high-volume samplers (Digitel DA-80H)

720 m³ **

24 h

500 L/min

Quartz filter

The filters were stored at −80 °C until analysis

The data of environmental factors were downloaded (O₃, nitrogen dioxide (NO₂), SO₂, carbon monoxide (CO), PM10, PM2.5, temperature, etc.)

Not reported

ORF1ab

Not clear

Not clear

SARS-CoV-2 was detected in PM10 and PM2.5 samples, but the number of samples is not specified

10^0 copies/m3 - 10^3.1 copies/m3 + 1

Not studied