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Dx

ICD-10-CM 2027 diagnosis code

X39.0Exposure to natural radiation

Not billable — use a more specific codeRequires 7th character

X39.0 is a header code, so it can't be reported by itself. Choose one of the 2 more specific codes beneath it and add the required 7th character.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About X39.0

X39.0 is the ICD-10-CM diagnosis code for exposure to natural radiation. It belongs to category X39 (exposure to other forces of nature), block X30-X39 (exposure to forces of nature) and chapter 20 (external causes of morbidity). It is a header code, so it can't be reported by itself; one of its 2 subcodes must be used instead.

Within X39 (exposure to other forces of nature), X39.0 is specifically for exposure to natural radiation. Related codes cover other exposure to forces of nature (X39.8).

Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.

Don't report X39.0 together with the conditions in its Excludes1 note: contact with and (suspected) exposure to radon and other naturally occurring radiation (Z77.123), exposure to man-made radiation (W88-W90) and exposure to sunlight (X32).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

7th character

The appropriate 7th character is to be added to each code from category X39

  • Ainitial encounter
  • Dsubsequent encounter
  • Ssequela

Coding notes

Excludes1Not coded here — never report together with this code
  • contact with and (suspected) exposure to radon and other naturally occurring radiation (Z77.123)
  • exposure to man-made radiation (W88-W90)
  • exposure to sunlight (X32)

Notes that apply from higher levels

Instructions written at a parent level also apply to X39.0.

Broader instructions also apply from Chapter 20: External causes of morbidity.

Codes whose notes reference X39.0

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about X39.0

Is X39.0 billable?

No. X39.0 is a header code. Report one of its more specific subcodes instead.