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§ 4.1 — Maryland

Radon mitigation in Maryland

This page lists 26 people and firms with a current radon mitigation credential whose official record names Maryland. Each row shows the credential number, the issuing body, and its own verification date. The latest record check on this page was October 13, 2026; other records may have been checked earlier. Source: the official file linked on each listing. Verify the number before you hire.

Latest credential check October 13, 2026. Methodology Individual record dates may be earlier. NRPP. NRSB.

Radon testingRadon mitigation

Testing listings are people credentialed to measure radon. Mitigation listings are people credentialed to install a reduction system. Some people appear on both lists when the official file says they hold both. The list is ordered by the city or county on each record. That place is where the record is filed, not a promise about where the person works.

26 listings. Type to narrow the list.

  1. Steve Hayes

    Target Radon

    current NRPP № 106501

    mitigation, Aberdeen

    (410) 913-6675October 13, 2026cite ↗

  2. Stephen W. Stran

    Harford Radon Consultants

    current NRPP № 100050

    mitigation, Abingdon

    (410) 836-2382October 13, 2026cite ↗

  3. David Marshall Leety

    Arc Environmental, Llc.

    current NRSB № RRS-12G004

    mitigation, Baltimore

    410-659-9971September 30, 2026cite ↗

  4. Edward Darcy

    Swat Environmental

    current NRPP № 107238

    mitigation, Baltimore

    (410) 323-4461October 13, 2026cite ↗

  5. Jamile Applewhite

    Swat Environmental

    current NRPP № 111110

    mitigation, Baltimore

    (610) 674-4421October 3, 2026cite ↗

  6. John S. Swett

    Radon Abatement Services

    current NRSB № RRS-1G0006

    mitigation, Chevy Chase

    September 30, 2026cite ↗

  7. Mike Bowersox

    Ben Lewis Plumbing

    current NRSB № RRS-12G001

    mitigation, Clarksburg

    September 30, 2026cite ↗

  8. Carl Pucci

    Affordable Radon Reduction, Inc.

    current NRPP № 104531

    mitigation, Dundalk

    (888) 584-8899October 13, 2026cite ↗

  9. Michael E. Walther

    Radon Industry Advocate

    current NRPP № 108980

    mitigation, Ellicott City

    (443) 956-1689October 3, 2026cite ↗

  10. Michael A Stansbury

    Belson Construction, Llc

    current NRPP № 107910

    mitigation, Emmitsburg

    (443) 280-2091October 13, 2026cite ↗

  11. Michael A. Stansbury

    Belson Construction, Llc

    current NRSB № RRS-18G014

    mitigation, Emmittsburgh

    September 30, 2026cite ↗

  12. Benjamins Zonis

    Handyman On Call Llc

    current NRPP № 111167

    mitigation, Finksburg

    (443) 850-6948October 3, 2026cite ↗

  13. Michael S. Jennemann

    Maryland Radon Laboratory, Inc.

    current NRSB № RRS-18G001

    mitigation, Finksburg

    September 30, 2026cite ↗

  14. Robert C Tsas

    Roberts Radon, Llc

    current NRPP № 109171

    mitigation, Gaithersburg

    (301) 750-2695October 3, 2026cite ↗

  15. Paul Jonathan Stalker

    Reliable Radon

    current NRPP № 109457

    mitigation, Laurel

    (410) 627-2055October 3, 2026cite ↗

  16. Paul Stalker

    Reliable Radon, Inc.

    current NRSB № RRS-19G018

    mitigation, Laurel

    September 30, 2026cite ↗

  17. Michael J. Deitz

    G.m.d. Construction, Inc.

    current NRPP № 100026

    mitigation, Lisbon

    (410) 442-1960October 13, 2026cite ↗

  18. Wendy Rimbey

    Gmd Construction, Inc.

    current NRPP № 108465

    mitigation, Lisbon

    (410) 442-1960October 3, 2026cite ↗

  19. William Tyler Ransley

    Gmd Construction

    current NRPP № 109471

    mitigation, Lisbon

    (410) 442-1960October 3, 2026cite ↗

  20. John Deitz

    G.m.d. Construction, Inc.

    current NRPP № 107909

    mitigation, Mount Airy

    (410) 442-1960October 13, 2026cite ↗

  21. Michael J. Deitz

    Gmd Construction Inc.

    current NRSB № RRS-G248

    mitigation, Mount Airy

    September 30, 2026cite ↗

  22. Peter Rosecrans

    Radon Resolvers, Llc

    current NRPP № 110523

    mitigation, Olney

    (301) 200-2907October 3, 2026cite ↗

  23. Alexander Gutman

    Ade Radon Mitigation Services, Llc

    current NRPP № 107458

    mitigation, Reisterstown

    (877) 609-7977October 13, 2026cite ↗

  24. Alexander Shpilman

    Alex's Radon Consulting, Llc

    current NRPP № 106630

    mitigation, Silver Spring

    (301) 660-0768October 13, 2026cite ↗

  25. Avi Kotek

    Kiwi Radon

    current NRPP № 115858

    mitigation, Silver Spring

    (301) 901-5494October 13, 2026cite ↗

  26. Shannon Neal Bittner

    Tri-state Environmental Solutions

    current NRPP № 104340

    mitigation, Williamsport

    (301) 491-8808October 13, 2026cite ↗
Fig. 4 — 25 of 26 listings have a mappable place. Each pin is a current listing at the Census city or county centroid on the file, approximate. Pins that share a place are spread so you can click them. Not street addresses.

Appendix A

Questions before you hire

How do I verify a radon credential listed for Maryland?

Open the source link on this page and match the name and credential number to the official file. Status can change after a record’s verification date. The latest record check on this page was October 13, 2026; check each record’s date. If the official page disagrees with this directory, trust the official page. We do not invent credential numbers.

Does EPA certify radon contractors?

The U.S. EPA does not certify radon contractors. EPA publishes guidance on finding a qualified radon service provider and points to state programs and national certifications. This directory is not affiliated with EPA. We do not display EPA-certified badges.

What does last verified mean on this page?

Last verified on an individual record is the date we checked its official source. The latest credential check on this page was October 13, 2026; other records may have earlier dates. We refresh the roster monthly. Current means the person appeared as currently credentialed on the source at that record’s verification date. Credentials can expire between refreshes, so follow the source link.

Appendix A.2

Before you hire

  1. Ask who holds the credential printed on this page, and ask them to show the same number. Some firms employ several credentialed people. The listing is the person or firm on the official file, not whoever answers the phone.
  2. Ask what test method or mitigation system they will use for this building. A credential is not a work plan. Testing and mitigation are separate services here, and a person appears on both lists only when the official file says they hold both.
  3. Ask how they will document test results or the finished mitigation system. Keep that document with the credential number you verified. This directory does not score jobs, publish reviews, or collect quotes.

The full checklist: How to choose a radon mitigation company: 6 checks before you sign

Maryland pages here use current NRPP or NRSB certifications. City pages use the city printed on that record, not a ZIP-radius search. A national certification is not a state license in Maryland. Some states require a separate state credential to work legally. Read the methodology. Credential status can change.