Radon in Commercial Buildings: What Michigan Business Owners Should Know

The radon conversation in Michigan — and nationally — is overwhelmingly focused on residential homes. That focus is understandable. Homes are where people spend the majority of their time, where children are raised, and where the cumulative exposure that drives long-term health risk accumulates most significantly. But radon does not stop at the property line of a single-family home. It rises from the same geology beneath commercial buildings, office complexes, retail spaces, warehouses, and mixed-use properties that it rises from beneath residential foundations. Michigan business owners who have never considered radon in their commercial properties are carrying an unknown risk that deserves direct attention.

Why Commercial Buildings Are Not Immune

The geological process that produces radon — the natural decay of uranium in soil and rock — is indifferent to what sits above it. A commercial building on a concrete slab in Kent County sits above the same Zone 1 geology as the residential neighborhoods surrounding it. The pressure dynamics that drive radon entry into homes apply equally to commercial structures. Sub-slab air at lower pressure than the building interior draws radon upward through foundation cracks, utility penetrations, slab joints, and any other available pathway — the same mechanisms we covered in our post on how radon enters a home, applied to a commercial context.

What differs between residential and commercial radon exposure is not the source or the entry mechanism but the occupancy patterns and the regulatory framework — or lack thereof — that governs testing and disclosure.

Occupancy and Exposure in Commercial Settings

The radon exposure risk in a commercial building depends significantly on how the building is used and how people occupy the space. Several commercial use types warrant particular attention.

Ground-floor and below-grade office space. Employees who work in ground-floor or basement offices in commercial buildings may spend eight or more hours per day in the space closest to the foundation — the same exposure pattern that makes finished basement home offices a priority in residential settings. A commercial office building with elevated radon levels in its lower floors is exposing its employees to a health risk they are almost certainly unaware of, and that the employer may be equally unaware of without testing.

Retail and service businesses in older commercial buildings. Michigan's commercial building stock includes a significant inventory of older structures — storefront retail, professional offices, and service businesses in buildings constructed decades before radon awareness existed. These buildings share many of the foundation vulnerability characteristics we discussed in our post on older Michigan homes: aging concrete, deteriorated mortar joints, accumulated foundation cracks, and utility penetrations that were never sealed with radon in mind.

Daycare and early childhood education facilities. Commercial spaces used for childcare and early education deserve specific attention because of the vulnerability of the population they serve. Children who spend long hours in a facility at ground level or below in a building with elevated radon levels accumulate exposure over the critical developmental years of their lives. This is addressed in more detail in our post on radon testing for schools and daycares, but it is worth flagging here as among the highest-priority commercial use types from a radon perspective.

Healthcare facilities. Medical offices, therapy practices, and health clinics that occupy ground-floor or below-grade commercial space present an ironic scenario — facilities dedicated to patient health operating in buildings that may have unaddressed air quality risks. Healthcare providers who become aware of radon risks in their facilities and address them proactively are aligning their physical environment with their professional mission.

Michigan's Regulatory Landscape for Commercial Radon

Michigan does not currently require radon testing in commercial buildings. There is no state law mandating testing or disclosure for commercial properties, no occupational health regulation that establishes radon action levels for workplaces, and no building code requirement for radon-resistant construction in new commercial builds.

This regulatory gap means that commercial radon testing in Michigan is entirely voluntary — driven by informed business owners, proactive property managers, and the occasional tenant who raises the question. OSHA has not established a permissible exposure limit for radon in workplaces at the federal level, though the EPA's residential action level of 4 pCi/L is generally used as the reference point for commercial settings in the absence of workplace-specific standards.

The absence of legal requirements does not reduce the health risk. It simply means the impetus for testing must come from the business owner or property manager rather than from regulatory compliance. Business owners who test voluntarily are not going above and beyond an arbitrary standard — they are addressing a real health risk that regulation has not yet caught up with.

Employer Responsibility and Risk Management

Michigan business owners have a general duty under OSHA's General Duty Clause to provide employees with a workplace free from recognized hazards that are causing or likely to cause death or serious physical harm. While radon has not been the subject of specific OSHA enforcement action in the way that asbestos or silica dust has been, it is a recognized health hazard with a documented association with lung cancer. A business owner who becomes aware of elevated radon in their workplace and takes no action occupies a legally and ethically uncomfortable position.

Beyond the legal dimension, there is a straightforward risk management argument for commercial radon testing. The cost of a professional commercial radon test is modest.

The cost of mitigation in a commercial building, while higher than residential mitigation due to larger footprints and more complex HVAC interactions, is a manageable capital expense. The cost of a workers' compensation claim, litigation, or reputational damage associated with a preventable occupational health issue is a different order of magnitude entirely.

Business owners who test and address elevated radon are not just protecting their employees — they are protecting themselves from a class of liability that grows more visible as radon awareness increases nationally.

Commercial Testing: How It Differs From Residential

Professional radon testing in commercial buildings follows the same fundamental principles as residential testing — devices placed in occupied areas at the lowest level of the building, under normal operating conditions for the building's HVAC system, over a defined test period. But commercial testing has its own considerations that differ from the residential context.

Building size requires more test devices. A single test device adequate for a residential home is insufficient for a commercial building with multiple zones, HVAC systems, and occupied areas. Commercial testing protocols typically call for multiple devices placed strategically across the building footprint to capture radon levels across different areas rather than at a single representative point.

HVAC systems in commercial buildings complicate radon dynamics in ways that residential HVAC systems do not. Large commercial HVAC systems may depressurize lower floors relative to upper floors, affect air exchange rates across the building, and create pressure dynamics that either amplify or attenuate radon entry depending on how they are configured and operated. Understanding how a specific building's HVAC system interacts with radon entry requires experience with commercial testing rather than simply scaling up residential protocols.

Normal building operating conditions during the test period matter. Closed-house protocols used in residential short-term testing do not translate directly to a commercial building that has employees coming and going, loading dock doors opening, and HVAC systems operating on commercial schedules. Commercial testing is typically conducted under normal building operating conditions rather than closed conditions, reflecting the fact that the goal is to measure actual exposure conditions rather than a worst-case sealed scenario.

The Property Transaction Dimension

Commercial real estate transactions in Michigan share the same radon disclosure gap as residential transactions — there is no legal requirement for sellers to test or disclose radon levels in commercial property sales. Commercial buyers conducting due diligence on a property acquisition would be well served by including radon testing in their environmental assessment process, particularly for properties with significant ground-floor or below-grade occupied space.

A commercial property with undisclosed elevated radon levels that is discovered post-acquisition becomes the buyer's problem in exactly the same way a residential radon problem does — but potentially at larger scale, with employee exposure liability added to the property remediation equation. Commercial buyers and their advisors who treat radon as part of standard environmental due diligence are protecting a significant investment from a known and addressable risk.

Taking Action as a Michigan Business Owner

If you own or manage a commercial building in Michigan — particularly one with ground-floor or below-grade occupied space — and radon testing has never been conducted, scheduling a professional commercial radon assessment is a straightforward and responsible step. The process is not dramatically more complex than residential testing, the cost is modest relative to other business operating expenses, and the information it provides is directly relevant to the health of the people who work in your building every day.

At All Michigan Mitigation, we bring the same focused expertise to commercial radon assessment and mitigation that we apply to every residential home we serve. Radon is the only thing we do, and that specialization means we approach commercial projects with the depth of knowledge that a complex built environment requires.

Visit us at allmichiganmitigation.com to discuss commercial radon testing for your building or to learn more about what the assessment process involves.

All Michigan Mitigation is a West Michigan radon testing and mitigation company dedicated exclusively to helping homeowners understand and eliminate radon risk in their homes.