5.3 Special Testing Scenarios & Multifamily/Commercial Reporting

5.3 Special Testing Scenarios & Multifamily/Commercial Reporting

While single-family residential testing represents the core of routine radon measurement, Radon Measurement Professionals (RMPs) frequently evaluate large, complex structures such as apartment complexes, condominiums, schools, office buildings, and commercial facilities. Testing these environments requires adherence to specialized ANSI/AARST standards: ANSI/AARST MAMF-2023 (Protocol for Conducting Measurements of Radon and Radon Decay Products in Multifamily Buildings) and ANSI/AARST MALB-2023 (Protocol for Conducting Measurements of Radon and Radon Decay Products in Schools and Large Buildings).

Multifamily Building Protocols (ANSI/AARST MAMF-2023)

Multifamily properties present unique structural layouts, shared ventilation systems, and complex tenant relations. RMPs must follow strict sampling frequencies to ensure statistical reliability across units.

Sampling Requirements for Multifamily Structures

• Ground-Contact Units: MAMF-2023 mandates testing in 100% of ground-contact dwellings, apartments, or occupied units (including units over slab-on-grade, crawlspaces, or basements).
• Upper-Floor Sampling: In multi-story buildings, elevated radon can occasionally occur on upper levels due to elevator shaft stack effects, utility chases, or building heating systems. Therefore, MAMF-2023 requires testing in a minimum of 10% of upper-floor units on each upper floor level.
• Non-Residential Ground-Contact Spaces: All ground-contact community rooms, management offices, daycares, and laundry facilities must also be tested.

Tenant Coordination and Notification

Unlike single-family homes occupied by a single homeowner, multifamily testing requires coordinating access across dozens or hundreds of individual tenants. RMPs must issue official Occupant Notification Letters at least 48 hours prior to test deployment. These notices instruct tenants regarding closed-building requirements, device preservation, and prohibition of device tampering or movement.

Commercial Buildings and Schools (ANSI/AARST MALB-2023)

Educational institutions and commercial office spaces operate under mechanical ventilation regimes that differ fundamentally from residential HVAC systems. ANSI/AARST MALB-2023 governs testing in these larger facilities.

Room Selection and Coverage Criteria

Under MALB-2023, radon detectors must be deployed in all frequently occupied rooms in contact with the ground or located above unventilated crawlspaces/basements. This includes individual classrooms, administrative offices, conference rooms, auditoriums, cafeterias, and gymnasiums. Storage closets, hallways, and restrooms are generally excluded unless occupied as work stations.

HVAC Operating Rules and Occupied Mode

A critical distinction in MALB-2023 is the mandate governing heating, ventilation, and air conditioning (HVAC) systems:

• Occupied Mode Requirement: Testing MUST occur while the building’s HVAC system is operating under normal occupied conditions (including scheduled fresh-air intake and ventilation rates).
• Managing HVAC Setbacks: Many schools and office complexes program HVAC systems to enter "unoccupied setback mode" on weekends, shutting down outdoor air dampers and reducing air circulation. If a 48-hour short-term test is conducted over a weekend during setback mode, artificial radon accumulation can occur, skewing results.
• Test Scheduling: RMPs must schedule short-term commercial tests during weekday periods (e.g., Tuesday to Thursday) when HVAC systems operate continuously in occupied mode, OR use continuous monitors to verify HVAC operating status.

Large-Building Data Management and Summary Reporting

Reporting radon results for a 200-unit apartment building or a 50-room high school requires specialized reporting structures. Generating dozens of standalone single-page reports is confusing and inefficient for property managers.

Master Building Summary Report

RMPs must author a consolidated Master Summary Report for property owners, school boards, or corporate managers. This master document must include:

1. Executive Summary: Overview of total rooms/units tested, number of units exceeding 4.0 pCi/L, overall building average, and top-level action recommendations.
2. Tabular Data Matrix: A complete table listing building name, unit/room number, floor level, detector serial numbers, deployment/retrieval dates/times, and exact pCi/L readings.
3. Floor Plan Maps: Building floor plans overlaying detector locations and highlighting units/rooms with elevated readings in color-coded formats.
4. Quality Control Summary: Results of duplicate detectors, field blanks, and spikes deployed during the large-building project (typically 10% duplicates, 5% blanks, 3% spikes).

Individual Tenant Disclosures

Property owners are often legally required to disclose radon test results to individual tenants. RMPs provide single-unit Tenant Disclosure Notices summarizing the specific reading for that tenant's apartment alongside standard EPA risk communication text.

Standard Comparison Across ANSI/AARST Testing Protocols