Studies in support of airborne transmission of respiratory pathogens
| Study | Country, Setting | Pathogen | Type of ventilation | Infection identified by | Main findings |
| Lu et al31 | China, restaurant | SARS-CoV-2 | Mechanical: standalone air conditioner (A/C) | Clinical diagnosis; unspecified | Development of symptoms in 12% of diners in the vicinity of the index patient; viral droplets propagated by A/C airflow |
| Kulkarni et al32 | UK, hospital | RSV | Mechanical: centralised, unspecified | PCR diagnosis | Virus-laden aerosols from index patient were present within 10 m radius, remained for 2 hours after the patient was discharged and infected respiratory epithelial cells in vitro |
| Wong et al33 | Hong Kong, hospital | Influenza | Mechanical: with HEPA filter close to index patient | RNA sequencing | Imbalanced airflow pattern facilitated infection transmission; identical viral strain in the index patient and contacts |
| Li et al34 | Hong Kong, hospital | SARS-CoV-1 | Mechanical: central air conditioning | Unspecified | CFDS showed an association between the concentration decay from the index patient’s bed and the spatial SARS infection pattern involving 138 people |
| Yu et al35 | Hong Kong, multifloor apartment complexes | SARS-CoV-1 | Natural and mechanical: central circulation system | Unspecified | Experimental studies showed that aerosols were generated and drawn in by an exhaust fan from contaminated sewage leading to infections on multiple floors |
| Olsen et al36 | Taiwan, aircraft | SARS-CoV-1 | Mechanical: aircraft ventilation | RT-PCR and serology | Proximity-dependent viral spread from a symptomatic host in aircraft |
| Jiang et al20 | China, hospital | SARS-CoV-1 | Natural and mechanical | Unspecified | Increased rate of HCW infection with a lower ratio of window size to room volume and laminar air flow mechanical ventilation but no (or closed) windows |
| Hoge et al37 | USA, jail | Streptococcus pneumoniae | Mechanical: HVAC | Culture and enzyme immunoassay | Increased incidence of pneumococcal disease (identical strain) with overcrowding and decreased outside air delivery by the ventilation system |
| Shigematsu and Minowa38 | Japan, building | Tuberculosis | Mechanical: central air conditioning | Unspecified | Indoor infection of tuberculosis attributed to interrupted ventilation leading to high carbon dioxide concentrations |
| Bloch et al39 | USA, paediatrician office | Measles | Mechanical: HVAC | Physician diagnoses | Measles outbreak in an office with a high volume of recirculated air via the dispersion of droplet nuclei from the index patient |
| Moser et al 40 | USA, aircraft | Influenza | Mechanical: interrupted aircraft ventilation | Culture and serology | Influenza outbreak-associated air travel with 3 hour interruption in aircraft ventilation; similar strain in 26% of contacts |
| Ehrenkranz and Kicklighter41 | USA, hospital | Tuberculosis | Mechanical: central air conditioning | Mantoux test | Tuberculosis outbreak associated with recirculation of air-containing droplet nuclei and lack of high-efficiency filters |
| Wehrle et al42 | Germany, hospital | Smallpox | Natural ventilation | Physician diagnosis | Outbreak of 17 cases of smallpox mediated by air currents and low relative humidity |
CFDS, computational fluid dynamic simulations; HCWs, healthcare workers; HVAC, heating ventilation and air conditioning system; MERS-CoV, Middle East respiratory syndrome-related coronavirus; RSV, respiratory syncytial virus; RT-PCR, real-time PCR; SARS-CoV-1, severe acute respiratory syndrome coronavirus 1; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.