Pan American Health Organization · 2020
Technical guidance on HVAC and natural ventilation systems to prevent respiratory pathogen transmission in healthcare settings during COVID-19.
- Issuer
- Pan American Health Organization
- Edition
- 2020
- Audience
- Healthcare facility managers, infection prevention and control teams, HVAC engineers, maintenance staff
- Evidence
- Expert consensus with references to WHO, CDC, and ASHRAE guidelines
- Reviewed
- 20 Oct 2026 · GMJ
What this guideline says
GMJ summary
This technical guidance addresses the critical role of heating, ventilation, and air conditioning (HVAC) systems in preventing pathogen transmission within healthcare facilities, with particular focus on COVID-19. The document emphasises that whilst respiratory infections are primarily transmitted via respiratory droplets, airborne transmission may occur during aerosol-generating procedures such as intubation, bronchoscopy, suctioning, nebulised treatment administration, manual ventilation, prone positioning, ventilator disconnection, non-invasive positive-pressure ventilation, tracheostomy, and cardiopulmonary resuscitation.
The guidance provides detailed operational and design specifications for both HVAC systems and natural ventilation settings. Key recommendations include maintaining temperature between 21°C–24°C, relative humidity 40–60%, minimum 2 air changes per hour, and ‘clean to less clean’ directional airflow. Special emphasis is placed on airborne infection isolation rooms with negative pressure for aerosol-generating procedures, MERV 13 or higher filtration for general environments, and HEPA filtration for special-care areas.
The document also addresses maintenance protocols, including disinfection of filters with 10% sodium hypochlorite solution for at least 5 minutes before disposal, and the critical requirement that HVAC systems remain continuously operational to prevent mould and fungal contamination. Specific guidance is provided for facilities relying on natural ventilation, including assessment of outdoor air quality before opening windows in intensive care units.
Key points
For clinicians — doses and thresholds as stated in the guideline
- Maintain temperature between 21°C–24°C (70°F–75°F) and relative humidity between 40–60% in all healthcare areas
- Implement minimum 2 air changes per hour (ACH) and maintain minimum 10m separation between exhaust outlets and outdoor air intakes
- Use MERV 13 or higher filtration for general environments and MERV higher than 13 for patient treatment areas; HEPA filtration required for special-care areas
- Utilise negative-pressure airborne infection isolation rooms for aerosol-generating procedures (intubation, bronchoscopy, suctioning, nebulised treatment, manual ventilation, prone positioning, ventilator disconnection, non-invasive positive-pressure ventilation, tracheostomy, CPR)
- Never turn off HVAC systems or air filtration equipment as this affects airflows and can cause mould and fungal contamination
- Disinfect filters with 10% sodium hypochlorite solution or appropriate disinfectant, allowing at least 5 minutes contact time before removal and disposal
- Monitor and record daily the proper negative-pressure function of isolation rooms; maintain doors closed and eliminate or minimise air recirculation
- In natural ventilation settings, assess ambient air quality (pollution, allergens, pollen, fungi) before opening windows in intensive care units
General Recommendations for HVAC Systems and Natural Ventilation to Prevent Virus Transmission
Table extracted from the guideline
| Item | Key Actions |
|---|---|
| General Planning Activities | Establish maintenance plan; assess ventilation system status to prevent respiratory infection transmission |
| HVAC System Design | Implement 'clean to less clean' airflow; minimum 2 ACH; 10m separation between exhaust/intake; avoid VAV systems |
| Operational Aspects | Maintain 40–60% humidity; keep 21°C–24°C temperature; do not turn off HVAC systems; ensure emergency power connection |
| Air Filtration (General) | Prefer MERV 13 or higher for general environments |
| Air Filtration (Clinical) | HEPA for special-care areas; MERV >13 for patient treatment areas; exhaust isolation rooms directly outside or through HEPA |
| Aerosol-Generating Procedures | Use negative-pressure isolation rooms; monitor daily; maintain doors closed; eliminate/minimise recirculation; source control options |
| Maintenance | Use PPE; disinfect filters with 10% sodium hypochlorite for ≥5 minutes; wash hands after activities |
Source: Pan American Health Organization, Recommendations for Heating, Ventilation, and Air Conditioning in Health Care Facilities. Reproduced in summary form.
From the guideline
Verbatim
“Do not regularly turn HVAC systems or air filtration equipment off. Doing so affects airflows and can cause contamination with agents such as molds and fungi.”
Editor’s perspective
Why this matters for Georgia and the region
Prof. Giorgi Pkhakadze, MD, MPH, PhD
Editor-in-Chief, Georgian Medical Journal · Chair, Public Health Institute of Georgia · WHO consultant, health and migration
As Georgia continues to strengthen its healthcare infrastructure, including recent investments in infection prevention and control capacity, these HVAC recommendations are directly applicable to both new construction and renovation of existing facilities. Many Georgian healthcare settings, particularly in rural areas, rely on natural ventilation rather than mechanical systems, making the guidance on window management and spatial separation during aerosol-generating procedures especially relevant for district hospitals and primary care centres. I would stress to Georgian clinicians the absolute requirement to maintain negative-pressure isolation rooms for procedures such as intubation and bronchoscopy, with daily monitoring and documentation—a practice that requires both technical capacity and sustained vigilance. The primary implementation challenge in our region will be balancing the recommendation to never turn off HVAC systems with the reality of energy costs and intermittent power supply in some areas, necessitating prioritisation of emergency power connections for critical-care zones and isolation facilities.
ORCID 0000-0001-7609-4515 · Perspective written for the GMJ Guidelines Library, 20 Oct 2026
Applicability
Georgia and the South Caucasus
For Georgia and the South Caucasus, this guidance is particularly relevant given the regional variation in healthcare infrastructure, with some facilities relying on natural ventilation rather than mechanical HVAC systems. National infection prevention and control programmes would need to conduct facility-level assessments to categorise healthcare settings by ventilation type, prioritise investment in negative-pressure isolation rooms for referral centres performing aerosol-generating procedures, and develop context-appropriate maintenance protocols. In resource-limited settings across Armenia, Azerbaijan, and Georgia, the natural ventilation guidance—including ambient air quality assessment and spatial separation strategies—offers practical alternatives where mechanical systems are unavailable, whilst the emphasis on not turning off existing HVAC systems addresses common energy-saving practices that may inadvertently increase infection risk.
Questions this guideline answers
Quick answers
What temperature and humidity should be maintained in healthcare facilities?
Temperature should be kept between 21°C–24°C (70°F–75°F) and relative humidity between 40–60%. These conditions are important for patient comfort, equipment operation, and infection control.
Which medical procedures require special airborne precautions?
Aerosol-generating procedures requiring negative-pressure isolation rooms include endotracheal intubation, bronchoscopy, open suctioning, nebulised treatment administration, manual ventilation before intubation, prone positioning, ventilator disconnection, non-invasive positive-pressure ventilation, tracheostomy, and cardiopulmonary resuscitation.
What type of air filtration is recommended for different healthcare areas?
General environments should use MERV 13 or higher filtration. Patient treatment areas require MERV higher than 13. Special-care areas and airborne infection isolation rooms require HEPA filtration, either fixed into the HVAC system or as portable units.
How should air filters be disinfected during maintenance?
Filters should be disinfected with a 10% sodium hypochlorite solution or another appropriate disinfectant approved for SARS-CoV-2, allowing it to act for at least 5 minutes before removal. Filters can then be bagged and disposed of in regular waste.
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Quality & accreditation
- ASF Hospital — Standard 18 — Sustainable Care
- ASF Hospital — Standard 5 — Safety & Emergency Preparedness
- ASF Medical Transport — Standard 5 — Infection Prevention & Control
- ASF Laboratory — Standard 7 — Examination: Process & Safety
- ASF Hospital — Standard 7 — Governance & Management
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- Issuer
- Pan American Health Organization
- Type
- Procedures, manuals, guidelines
- Status
- Current
- Published
- 2020-01-01
- Scope
- Healthcare facilities performing aerosol-generating procedures and managing respiratory infections including COVID-19
- Audience
- Healthcare facility managers, infection prevention and control teams, HVAC engineers, maintenance staff
- Licence
- CC BY-NC-SA 3.0 IGO
- Evidence
- Expert consensus with references to WHO, CDC, and ASHRAE guidelines
- Record history
- Created 20 Oct 2026 · updated 20 Oct 2026 · next check Apr 2027
Pan American Health Organization. Recommendations for Heating, Ventilation, and Air Conditioning in Health Care Facilities. Washington, D.C.: PAHO; 2020. (PAHO/CDE/CE/COVID-19/20-0029).GMJ Guidelines Library records are original summaries written by the GMJ editorial team from the issuer’s published document and reviewed by a physician. They do not replace the full guideline. The document is the copyright of its issuer and is linked, not hosted. Spotted an error or a newer edition? Tell the Guidelines Desk.
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