4.2 Infection Control Risk Assessment (ICRA 2.0) & Containment Protocols
Key Takeaways
- The ASHE ICRA 2.0 Matrix categorizes construction activity (Types A through D) and patient risk groups (Groups 1 through 4) to determine required containment Class (Class I through Class V).
- Class IV and Class V ICRA precautions mandate ante-rooms, negative air pressure differential (minimum -0.02 inches of water gauge / -5 Pascals), HEPA filtration units, and continuous differential pressure monitoring.
- Air change rates within containment enclosures must achieve a minimum of 6 to 12 air changes per hour (ACH) with HEPA units exhausting outside or utilizing certified HEPA recirculation.
- Daily inspection logs, particle counts (0.5 µm and 5.0 µm particles), and barrier integrity walkthroughs are critical for compliance and defending against healthcare-associated infections (HAIs).
- Water intrusion, plumbing disruptions, and dust suppression require rigorous controls to prevent opportunistic fungal pathogens such as Aspergillus and bacterial pathogens such as Legionella.
Infection control during healthcare construction is a matter of life and death. Environmental opportunists such as Aspergillus species mold spores—naturally present in soil, dry wall dust, ceiling tiles, and building insulation—are harmless to healthy individuals. However, when inhaled by immunocompromised patients (such as bone marrow transplant recipients, oncology patients, or organ transplant recipients), these microscopic spores cause invasive pulmonary aspergillosis, a condition carrying mortality rates exceeding 50%. Furthermore, disruption of domestic water systems can mobilize Legionella pneumophila biofilms, posing severe respiratory risks.
To mitigate these environmental hazards, the American Society for Health Care Engineering (ASHE) published the updated ICRA 2.0 (Infection Control Risk Assessment) standard. The Certified Healthcare Facility Manager (CHFM) must master ICRA 2.0 matrix execution, containment engineering, airflow dynamics, and daily compliance oversight.
The ASHE ICRA 2.0 Assessment Matrix
Determining the appropriate level of infection control containment requires a two-step matrix process: identifying the Construction Activity Type and cross-referencing it with the Patient Risk Group of surrounding clinical areas.
Step 1: Construction Activity Types (A through D)
- Type A: Inspection and non-invasive activities. Includes removing individual ceiling tiles for visual inspection (1 tile per 50 sq ft), painting without sanding, minor electrical trim, or wall covering repairs.
- Type B: Small-scale, short-duration activities creating minimal dust. Includes cutting drywall for electrical boxes, plumbing access, or cable pulling above ceiling tiles in limited areas.
- Type C: Work that generates moderate to high levels of dust or requires demolition of fixed building components. Includes sanding drywall, removing floor coverings, minor wall construction, and pulling major electrical conduits.
- Type D: Major demolition, structural construction, and heavy renovation projects. Includes core drilling, replacing major HVAC ductwork, wall removal, and continuous multi-room construction.
Step 2: Patient Risk Groups (Group 1 through Group 4)
- Group 1 (Low Risk): Office areas, non-patient administrative corridors, engineering workshops.
- Group 2 (Medium Risk): Physical therapy, outpatient clinics, radiology, nuclear medicine, waiting rooms.
- Group 3 (High Risk): Emergency Department, labor and delivery, pharmacy, general inpatient surgical wards, pediatric units.
- Group 4 (Highest Risk): Bone Marrow Transplant (BMT) units, Oncology ICUs, Organ Transplant units, Operating Rooms (ORs), Cath Labs, Neonatal ICU (NICU), Burn Units.
Step 3: Determining Containment Class (Matrix Crossing)
| Construction Activity | Group 1 (Low Risk) | Group 2 (Medium Risk) | Group 3 (High Risk) | Group 4 (Highest Risk) |
|---|---|---|---|---|
| Type A | Class I | Class II | Class II | Class III |
| Type B | Class II | Class II | Class III | Class IV |
| Type C | Class II | Class III | Class IV | Class V |
| Type D | Class III | Class IV | Class V | Class V |
ICRA Containment Classes & Engineering Standards
Each ICRA Class mandates specific physical barriers, ventilation controls, and operational protocols:
+-----------------------------------------------------------------------------------+
| ICRA CLASS IV / V CONTAINMENT LAYOUT |
+-----------------------------------------------------------------------------------+
| |
| +--------------------------+ Airlock +----------------------------------+ |
| | |====Door===| | |
| | ANTE-ROOM | | ACTIVE WORK ZONE | |
| | (Step-off Mat / PPE) | | (Negative Pressure Enclosure) | |
| | | | | |
| +------------||------------+ +------------------||--------------+ |
| || Enclosure || |
| || Door || Exhaust |
| / / |
| Hospital Corridor HEPA Unit (Exhaust Out/Recirc) |
| (Positive relative pressure) (Minimum -0.02" w.g. pressure) |
+-----------------------------------------------------------------------------------+
Detailed Class Requirements:
- Class I & Class II: Require basic dust suppression, damp wiping, misting work surfaces with water before drilling, and placing sticky walk-off mats at work zone exits.
- Class III: Demands dust-tight plastic containment barriers (minimum 6-mil flame-retardant polyethylene) completely sealed with tape from floor to true structural deck, HEPA-filtered negative air machines, and sealing of unused HVAC supply/return registers.
- Class IV: Requires rigid plastic modular panels or drywall containment barriers, a dedicated Ante-Room (Airlock) for staff PPE donning/doffing and equipment de-contamination, continuous differential pressure monitoring, negative pressure of at least -0.02 inches of water gauge (-5 Pascals), and HEPA air scrubbing.
- Class V: The stringent standard for heavy demolition near Group 4 patients. Mandates hard-wall flame-retardant rigid barriers, sealed ante-room with dual doors, dedicated HEPA exhaust directly to the building exterior, vacuuming of worker coveralls prior to exit, particle count monitoring, and 24/7 digital pressure logging with remote alarms.
Negative Air Pressure & Air Change Rate Calculations
To prevent airborne contaminants from migrating into clean hospital corridors, work zones under Class III, IV, and V must maintain continuous negative air pressure relative to surrounding spaces.
Air Changes Per Hour (ACH) Formula:
\text{ACH} = \frac{\text{Airflow Volume (CFM)} \times 60}{\text{Containment Room Volume (Cubic Feet)}}$$$$\text{CFM Required} = \frac{\text{Containment Room Volume (Cubic Feet)} \times \text{Desired ACH}}{60}
Calculation Example:
A healthcare facility manager is setting up a Class IV containment enclosure for a pharmacy cleanroom prep project. The enclosure measures 30 feet long, 20 feet wide, and has a 10-foot ceiling.
- Calculate Volume: $\text{Volume} = 30 \times 20 \times 10 = 6,000\text{ cubic feet}$.
- Target ACH: ASHE ICRA 2.0 mandates a minimum of 12 Air Changes Per Hour (ACH) for Class IV containment.
- Calculate CFM Required:
- Equipment Selection: The CHFM must deploy a negative air unit rated for at least 1,200 CFM under loaded HEPA filter conditions (or two 1,000 CFM units to provide redundancy).
HEPA Filtration & Exhaust Protocols:
High-Efficiency Particulate Air (HEPA) filters must be certified to capture 99.97% of particles down to 0.3 microns in size. Exhaust air from negative air machines should ideally be duct-vented directly to the outside of the building, away from fresh air intakes. If exterior venting is impossible, exhaust air may recirculate into non-patient areas only after passing through a primary HEPA filter and a secondary redundant inline HEPA unit.
Daily Inspection Protocols & Particle Counting Walkthroughs
Containment systems are only as effective as their daily maintenance. The CHFM or designated ICRA inspector must conduct daily site walkthroughs and maintain an on-site compliance binder.
Daily ICRA Walkthrough Checklist Items:
- Pressure Verification: Inspect continuous digital manometer displays to confirm negative pressure is at or exceeding -0.02" w.g. (-5 Pa). Verify visual ball-in-tube or magnehelic indicators.
- Barrier Integrity: Check polyethylene seals, zipper doors, rigid wall seams, and deck-level seals for tears or gaps.
- Ante-Room Mechanics: Verify sticky mats are clean and replaced daily. Ensure worker coveralls, shoe covers, and HEPA vacuums are utilized.
- HVAC Isolation: Confirm supply and return grilles inside containment are completely capped with airtight plastic to prevent dust from entering the main building HVAC system.
- Particle Counting Baseline Comparison: Use a calibrated laser particle counter to measure 0.5 µm and 5.0 µm particle concentrations inside containment, inside the ante-room, and in the adjacent clean corridor. Elevated particle counts in the clean corridor indicate barrier leakage requiring immediate work shutdown.
According to the ASHE ICRA 2.0 matrix, a major demolition project (Type D) scheduled directly adjacent to a Bone Marrow Transplant Unit (Group 4 Patient Risk) requires which containment classification?
What is the minimum continuous negative pressure differential required inside a Class IV ICRA containment enclosure relative to surrounding clean hospital areas?
A 2,000 cubic foot ICRA containment enclosure requires a minimum of 12 air changes per hour (ACH). What minimum airflow capacity (in CFM) must the HEPA negative air machine provide?