The concept of air quality originated in operating theatres in healthcare facilities. Indeed, until the second half of the 19th century, postoperative infections were responsible for significant mortality. It was Lister who first introduced the concept of antisepsis in operating theatres. As a result, he reduced postoperative mortality from 45% to 15% for amputations. Several studies subsequently demonstrated the benefits of treating the air to reduce healthcare-associated infections. Outside operating theatres, other medical-technical areas also require environmental control, such as controlled-atmosphere areas in pharmacies for the preparation of medicines, sterilization packaging rooms, and similar facilities.
Furthermore, healthcare facilities accommodate immunocompromised patients who are at very high risk of infection, particularly fungal infections. Among the care units concerned are protected hematology units, transplant units, burn units, and intensive care units. The incidence of invasive aspergillosis varies depending on the underlying condition, ranging from 1% for lupus to 26% for lung and heart-lung transplantation. Mortality associated with invasive pulmonary aspergillosis can reach 90%. It remains high despite appropriate antifungal treatment. Prevention is therefore essential. To guide healthcare facilities in controlling airborne contamination and defining controlled environments, the NF S90-351 standard was developed.
**NF S 90-351 Requirements Table:**
| Risk Class |
Particulate Cleanliness Class |
Particle Removal Kinetics |
Microbiological Cleanliness Class |
Differential Pressure |
Temperature Range |
Airflow Regime in the Protected Area |
| 4 | ISO 5 | CP 5 | M1 | 15 ± 5 Pa | 19 °C to 26 °C | Unidirectional airflow |
| 3 | ISO 7 | CP10 | M10 | 15 ± 5 Pa | 19 °C to 26 °C | Unidirectional or non-unidirectional airflow |
| 2 | ISO 8 | CP 20 | M100 | 15 ± 5 Pa | 19 °C to 26 °C | Non-unidirectional airflow |
For any further questions regarding the compliance of your installations or to obtain a customized audit of your controlled-atmosphere areas, please do not hesitate to contact our team of experts in hospital air treatment.