Table 1. Summary of Included Studies Evaluating the Air Contamination With SARS-CoV-2 in the Hospital Environment.
| Source | Setting | Clinical context | Location | Air ventilation | Distance from patients, m | Duration (air volume per sample, L) | Microbiology | SARS-CoV-2 | Positivity, No./total No. (%) | |
|---|---|---|---|---|---|---|---|---|---|---|
| Viral load, RNA copies/m3 | Viral culture, No./total No. (%) | |||||||||
| ICU patient environments | ||||||||||
| Liu et al,9 2020 | ICU | Severe | IR | Negative pressure | ND | 5 h-7 d (1500-50 400 ) | ddPCR | 31 113 | NA | 2/3 (66) |
| Faridi et al,8 2020 | ICU | Severe | Multiple-bed room | Mechanical or natural | 2-5 | 60 min (90) | RT-PCR; Ct, 38 | NA | NA | 0/9 |
| Guo et al,11 2020 | ICU | Severe | IRs, bay room | 12 Air supplies; 16 air discharges/h | ND | 30 min (300) | RT-qPCR | Mean: 3.8 near air outlet; 1.4 near patients | NA | 13/32 (41); Ct, 35.7 and 44.4 |
| Lei et al,22 2020 | ICU | Critical | Multiple-bed room | ND | 1 | 4 h (1260) | RT-qPCR | NA | NA | 0/1; Ct, 41.5 |
| Li et al,10 2020 | ICU | Severe | Multiple-bed room; 3 beds | 12 Air supplies; 16 air discharges/h | 1-5 | 5 h (21 600) | RT-PCR; Ct, <37 and >40 | NA | NA | 0/9 |
| Zhou et al,19 2020 | ICU | ND | ND | Natural ventilation | 1-5 | 40 min (600-16 000) | RT-qPCR; Ct, 39.5 | NP | NA | 0/5 |
| Razzini et al,23 2020 | ICU | 2 Patients intubated, 1 patient not intubated | Multiple-bed room | Negative pressure | ND | 40 min (2000) | RT-PCR | Mean, 22.7 | NA | 12/12 (100) |
| Ding et al,18 2020 | ICU | Mild | IRs | Negative pressure | 0.5 | 20-30 min (300-10 000) | RT-PCR | NA | NA | 0/26 |
| Ahn et al,27 2020 | ICU | 3 Patients intubated | IRs | Negative pressure and 12 air changes/h | 1 | 20 min (250) | rRT-PCR; Ct, <35; viral culture | NA | NP | 0/3 |
| Kenarhoohi et al,28 2020 | ICU | 6 Critical | Multiple beds; 10 patients | Natural | ≥2 | 180 min (2160) | RT-PCR; Ct, <40 | NA | NA | 0/6 |
| Jin et al,29 2020 | ICU | 1 Critical | IR | Negative pressure | 0.5 | 15 min (6000) | qRT-PCR; Ct, <40 | NA | NA | 1/1 (100) |
| Tan et al,25 2020 | ICU | 9 Severe or critical | Single room | Natural ventilation | 1 | 60 min (300) | RT-PCR | NA | NA | 1/10 (10) |
| Non-ICU patient environments | ||||||||||
| Liu et al,9 2020 | GW | Severe | 4 Single and 1 multiple-bed room; 2 beds | Negative pressure | ND | 5 h (1500) | ddPCR | 0 | NA | 0/2 |
| Faridi et al,8 2020 | GW | Severe | Multiple-bed room; 2-9 beds | Mechanical or natural | 2-5 | 60 min (90) | RT-PCR; Ct, 38 | NA | NA | 0/1 |
| Ong et al,3 2020 | GW | Moderate or mild | IRs | 12 Air exchanges/h | <1 and 2-5 | 4 h (3600) | RT-PCR; Ct, 45 | ND | NA | 0/18 |
| Santarpia et al,12 2020 | IW | Mild | IRs | Negative pressure | Bedside table or desk | 15 min (750) | RT-PCR; Ct, 45; viral culture | NA | 0/10 | 0/18 |
| Guo et al,11 2020 | GW | Mild | Single bay room | 8 Air supplies and 12 air discharges/h | Near patients, near air outlet | 30 min (300) | RT-qPCR | 0.68 near air outlet | NA | 2/16 (12.5) |
| Chia et al,16 2020 | GW | Mild or asymptomatic | IRs | 12 Air changes/h | 1 and 2.1 | 4 h (840) | RT-PCR | Mean (range), 1.3 (0.916-2) | NA | 4/10 (40) |
| Lei et al,22 2020 | IW | Critical | ND | ND | 1 | 4 h (1260) | RT-qPCR | NA | NA | 1/1 (100); Ct, 44.6 |
| Cheng et al,14 2020 | IW | Severe, mild, asymptomatic | IRs | 12 Air changes/h, shelter | 0.1 | 20 min (1000) | RT-PCR | 0 | NA | 0/6 |
| Cheng et al,21 2020 | IW | ND | IRs | Negative pressure | 0.1 | 5 min (1000) | RT-PCR | 0 | NA | 0/8 |
| Zhou et al,17 2020 | IW and GW | ND | ND | ND | ND | ND (1000) | RT-qPCR; Ct, <40.4; viral culture | mean (range), 1.17 (0.16-7.04) | 0/12 | 6/12 (50) |
| Li et al,10 2020 | IW | Severe | Multiple-bed room; 3 beds | 8 Air supplies; 12 air discharges/h | 1-5 | 5 h (21 600) | RT-PCR; Ct, <37 and >40 | NA | NA | 0/18 |
| Wei et al,15 2020 | IW | Mild or asymptomatic | IRs | 12 Air exchanges/h | 0.6 | 15 min (1500) | RT-PCR; Ct, <35 | NA | NA | 0/6 |
| Zhou et al,19 2020 | GW | ND | IRs | Natural | 1-5 | 40 min (600-16 000) | RT-PCR; Ct, <39.5 | NA | NA | 0/16 |
| Santarpia et al,13 2020 | ND | ND | IRs | ND | ND | 30 min (ND) | RT-qPCR; viral culture | 2.41 TCID50/cm3 of air | 3/18 (17) | 18/18 (100) |
| Kim et al,24 2020 | IW and GW | 7 Mild and 1 asymptomatic | IRs; 5-bed room | IR with 15 air changes/h; IR without negative pressure; room without negative air pressure | 2 | 20 min (1000) | rRT-PCR; Ct, <35 | NA | NA | 0/32 |
| Tan et al,25 2020 | IW | 15 Mild | 3 Patients per room | Natural ventilation | 1 | 60 min (300) | RT-PCR | NA | NA | 1/2 (50) |
| Binder et al,26 2020 | IW | 4 Asymptomatic; 16 mild | Single rooms | 14 Air exchange/h | 1, 1.4, 2.2, and 3.2 | 240 min (840) | RT-PCR; viral culture | NA | 0/3 | 3/160 (1.9) |
| Kenarhoohi et al,28 2020 | Laboratory, radiology, internal medicine, emergency | 5 Mild and 1 suspected case | Multiple rooms, 18-30 patients | Natural | ≥2 | 180 min (2160) | RT-PCR; Ct, <40 | NA | NA | 0/6 |
| Lednicky et al,30 2020 | IW | 2 Patients with mild disease | IRs | 6 Air changes/h | 2-4.8 | 180 min (ND) | RT-PCR; viral culture |
Mean (range), 46 (16-94); 2-74 TCID50 U/L of air | 4/4 (100) | 4/4 (100) |
| Toilet or bathroom | ||||||||||
| Liu et al,9 2020 | Non-ICU | NA | Patient mobile toilet room | No ventilation | NA | 20 h (6000) | ddPCR | 1 | NA | 1/1 (100) |
| Ong et al,3 2020 | GW | NA | IRs | ND | NA | 8 h (2400) | RT-PCR; Ct, 45 | NA | NA | 0/6 |
| Lei et al,22 2020 | IW | NA | Patient bathroom | ND | NA | 4 h (1680) | RT-qPCR | NA | NA | 2/2 (100); Ct, 35.6, 35.5 |
| Zhou et al,17 2020 | Cohort ward | NA | Outside patient bay, in the ward | ND | NA | ND (1000) | RT-qPCR; Ct, <40.4; viral culture | 0.464 | 0/2 | 1/2 (50) |
| Zhou et al,19 2020 | Fever clinic | NA | In the ward | Natural | NA | 40 (16 000) | RT-PCR; Ct, <39.5 | NA | NA | 0/3 |
| Ding et al,18 2020 | 4 ICU | NA | Patient bathroom | 4 With negative pressure | NA | 20-30 min (420-10 000) | RT-PCR | NA | NA | 1/7 (14) |
| Clinical areas | ||||||||||
| Liu et al,9 2020 | Non-ICU | ND | Workstation | Natural | ND | 320-1200 min (1600-6000) | ddPCR | 0, 1, 1, 5, 9 | NA | 4/5 (80) |
| Ong et al,3 2020 | ICU and non-ICU | ND | Corridor, anteroom | NA | ND | 15 min (3000); 480 min (2400) | RT-PCR; Ct, 45 | NA | NA | 0/12 |
| Santarpia et al,12 2020 | ND | Mild | Floor adjacent to rooms | NA | >6 ft | 15 min (750) | RT-PCR; Ct, 45; viral culture | 2.58, 3.76 | 0/3 | 2/3 (66) |
| Guo et al,11 2020 | ICU, GW | 1 Severe, ND | Near office, pharmacy, nurse station, corridor, and buffer room | ND | ND | 30 min (27 000-72 000) | RT-qPCR | 0.54 | NA | 1/34 (3) |
| Wu et al,20 2020 | 1 ICU | Ward and various clinical rooms | ND | ND | ND | 30 min (ND) | RT-PCR; Ct, 43 | NA | NA | 0/69 |
| Zhou et al,17 2020 | ICU and non-ICU | ND | Nurse station, ward, ambulatory waiting room, Resus bay, CPAP unit | ND | ND | ND (1000) | RT-qPCR; Ct, <40.4; viral culture | 0.404, 0.035, 1.922, 0.031 | 0/10 | 4/10 (40) |
| Li et al,10 2020 | ICU and non-ICU | Severe | Corridor, clinic, buffer room | 1 With negative pressure | ND | 250 min (21 600) | RT-PCR; Ct, <37 and >40 | NA | NA | 0/45 |
| Zhou et al,19 2020 | ND | ND | Corridor and preroom | Natural | ND | 40 min (16 000) | RT-PCR; Ct, <39.5 | NA | NA | 0/18 |
| Razzini et al,23 2020 | ND | ND | Corridor | ND | ND | 40 min (16 000) | RT-PCR | NA | NA | 8/8 (100); Ct, 31.1 |
| Ding et al,18 2020 | IW | 3 Mild, ND for others | Ward, corridor, nurse station, and storage room | 3 Negative pressure, ND for others | ND | 20-30 (300-10 000) | RT-PCR | NA | NA | 1/12 (8); Ct, 37.8 |
| Kim et al,24 2020 | IW and GW | 7 Mild and 1 asymptomatic | 5 Anterooms, regardless of room type | ND | ND | 20 min (1000) | RT-PCR; Ct, <35 | NA | NA | 0/20 |
| Kenarhoohi et al,28 2020 | ICU entrance | NA | NA | Natural | NA | 180 min (2160) | RT-PCR; Ct, <40 | NA | NA | 0/1 |
| Staff areas | ||||||||||
| Liu et al,9 2020 | ICU | NA | Changing, meeting, and dining rooms, warehouse | Natural and/or mechanical; small air purifier | NA | 300-1200 min (1500-6000) | ddPCR | Mean, 13.8 | NA | 10/13 (77) |
| Santarpia et al,12 2020 | IW | NA | Personal air sample | NA | ND | NA | RT-PCR; Ct, 45 | Mean, 20.037 | NA | 4/4 (100) |
| Guo et al,11 2020 | ICU and GW | NA | Dressing rooms | NA | ND | 30 min (45 000-108 000) | RT-qPCR | NA | NA | 0/36 |
| Santarpia et al,13 2020 | ND | NA | Staff and changing rooms | NA | ND | ND (1000) | RT-qPCR; Ct, <40.4; viral culture | 0.249 | 0/4 | 1/4 (25) |
| Li et al,10 2020 | ICU and IW | NA | Conference room and clean zone | 2/3 With negative pressure | ND | 270-540 min (21 600-43 200) | RT-PCR; Ct, <37 and >40 | NA | NA | 0/45 |
| Zhou et al,19 2020 | ND | NA | Waste storage | Natural | ND | 40 min (16 000) | RT-PCR; Ct, <39.5 | NA | NA | 0/2 |
| Razzini et al,23 2020 | ND | NA | Changing and locker rooms | NA | ND | 40 min (8000-14 000) | RT-PCR | ND | NA | 0/17 |
| Jin et al,29 2020 | ICU | NA | Changing room | Negative pressure | Middle | 15 min (6000) | qRT-PCR; Ct, <40 | NA | NA | 0/1 |
| Public areas | ||||||||||
| Liu et al,9 2020 | NA | NA | Pharmacy, hall, office, store, and supermarket | Mechanical, natural, outdoor | NA | 300-1000 min (1500-5000) | ddPCR | 3, 7, 11, 3 | NA | 4/11 (36) |
| Santarpia et al,12 2020 | NA | NA | Hallway | ND | NA | ND (ND) | RT-PCR; Ct, 45; viral culture | 0.979-8.688 | 0/12 | 8/12 (67) |
| Wu et al,20 2020 | NA | NA | Public area | ND | NA | 30 min (ND) | RT-PCR; Ct, 43 | NA | NA | 0/6 |
| Zhou et al,17 2020 | NA | NA | Main entrance, toilet entrance, and lift area | ND | NA | ND (1000) | RT-qPCR; Ct, <40.4; viral culture | 1.574, 1.545 | 0/3 | 2/3 (67) |
| Li et al,10 2020 | NA | NA | Public area | ND | NA | 270 min (21 600) | RT-PCR; Ct, <37 and >40 | NA | NA | 0/9 |
| Kenarhoohi et al,28 2020 | Hospital entrance | NA | NA | Natural | NA | 180 min (2160) | RT-PCR; Ct, <40 | NA | NA | 0/1 |
Abbreviations: CPAP, continuous positive airway pressure; Ct, cycle threshold; ddPCR, droplet-digital polymerase chain reaction; GW, general ward; ICU, intensive care unit; IR, isolation room; IW, isolation ward; NA, not applicable; ND, not detailed; NP, not performed; RT-PCR, reverse transcription–polymerase chain reaction; RT-qPCR, quantitative reverse transcription–polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.