Richmond Hill, ON, Canada

Radon testing in Richmond Hill

Latest credential check on this page: September 14, 2026. Each record carries its own date. Canadian sources and verification.

1 current C-NRPP testing credentials whose official record names Richmond Hill, Ontario. This is partial coverage of professionals with an address in this city, not a list of everyone who serves it.

A C-NRPP certification is not a provincial licence. Confirm the credential and ask whether the professional serves your building before hiring. Check a C-NRPP number.

Name / company	City	C-NRPP credential	Service	Valid through	Last verified
Tianchen Zhang Custom Build Standard Construction Corp.	Richmond Hill	CRT-202884	testing	July 1, 2027	September 14, 2026

Fig. 1 — Richmond Hill, approximate. Pin marks the official Canadian Geographical Names Database city reference point, not a business address or service area.

Map source: Natural Resources Canada — Richmond Hill. Contains information licensed under the Open Government Licence – Canada.