Gregory R. Mason, M.D.
Pulmonary Disease Physician · Torrance, CA
Gregory R. Mason, M.D. is a pulmonary disease physician with a practice address in Torrance, California, and NPI 1841247145, issued on May 30, 2006. Check the license (California C36997, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Gregory R. Mason
- Credential
- M.D.
- Primary taxonomy
- Pulmonary Disease Physician 207RP1001X
- License number
- C36997 CA
Self-reported in NPPES; status is on the state search - Practice location
- 21840 Normandie Ave, Torrance, CA 90502
- Phone
- (310) 222-5101
- Enumerated
- May 30, 2006
- Record last updated
- May 16, 2019 (not updated in 7 years: call before relying on the address or phone)
- Fax
- (310) 320-5463
- Medicaid ID
- 00C369970 CA
- Entity
- Type 1 · individual
8 nearest pulmonary disease physician records → All 1,443 in California → Look up another NPI →
Also registered at 21840 Normandie Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Sudhir Anand, M.D.Pediatric Nephrology Physician1750360426
- Thomas Anderson, MDNeurology Physician1750304234
- Morris Asch, M.D.Pediatric Surgery Physician1619957784
- Lilly Barba, M.D.Nephrology Physician1407835978
- Peter Barrett, M.D.Internal Medicine Physician1568441954
- Barry Baylen, M.D.Pediatric Cardiology Physician1346229879
Verify Gregory R. Mason in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license C36997Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
97% fewer Medicare Part D claims than the average pulmonary disease physician in 2024
44 Medicare Part D claims, against an average of 1,425 among the 11,596 providers of this specialty who prescribed in Part D.
Most prescribed
- Wixela Inhub18 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Gregory R. Mason among 1,443 pulmonary disease physician records in California
Gregory R. Mason, M.D. is one of 1,443 pulmonary disease physician records with a practice address in California. 84% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 7% of them.
- NPI issued2006 · 7% of these records are older, 51% newer
- In a Medicare fileYes · 84% of these records are
- In the CMS Doctors and Clinicians fileNo · 74% of these records are
- Record last updated2019 · 55% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RP1001X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Pulmonary Disease Physician providers in California
There are 1,443 pulmonary disease physician records in California.
All 1,443 in California → Every provider in Torrance → Pulmonary Disease Physician nationwide →
The 8 pulmonary disease physician records with the nearest ZIP codes
- David Briganti, DOTorrance, CA 905021912534553
- Richard Casaburi, M.D.Torrance, CA 905021639149289
- Daniel DacostaTorrance, CA 905021023428570
- Richard Effros, M.D.Torrance, CA 905021306818885
- Adriel Fajilan, M.D.Torrance, CA 905021841637360
- Radhika Reddy, MDTorrance, CA 905021215226915
- Kathy Sietsema, M.D.Torrance, CA 905021053322032
- William Stringer, M.D.Torrance, CA 905021487633111
Common questions
What is Gregory R. Mason, M.D.'s NPI number?
Gregory R. Mason, M.D.'s National Provider Identifier (NPI) is 1841247145, issued on May 30, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Gregory R. Mason, M.D. located?
The NPPES record lists a practice address at 21840 Normandie Ave, Torrance, CA, 90502. Phone: (310) 222-5101. Providers update this record themselves, so call before visiting.
How can I verify Gregory R. Mason, M.D.'s license?
NPPES lists California license number C36997, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Gregory R. Mason, M.D. prescribe under Medicare Part D?
In 2024, Gregory R. Mason, M.D. had 44 Medicare Part D claims; the average among pulmonary disease physician prescribers was 1,425. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.