ICD-10-CM 2027 diagnosis code
W99.XXXAExposure to other man-made environmental factors, initial encounter
W99.XXXA is a valid, billable ICD-10-CM code for exposure to other man-made environmental factors, initial encounter. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Exposure to oth man-made environmental factors, init encntr
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 W99.XXXA
W99.XXXA is the ICD-10-CM diagnosis code for exposure to other man-made environmental factors, initial encounter. It belongs to category W99 (exposure to other man-made environmental factors), block W85-W99 (exposure to electric current, radiation and extreme ambient air temperature and pressure) and chapter 20 (external causes of morbidity). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
The 7th character "A" means initial encounter: use it while the patient is receiving active treatment for the condition.
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
It is exempt from present-on-admission (POA) reporting, so no POA indicator is required.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as E902.8 (accident due to changes in air pressure due to other specified causes).
7th character
Ainitial encounter
Other encounter types for W99:
Notes that apply from higher levels
Instructions written at a parent level also apply to W99.XXXA.
Broader instructions also apply from W85-W99 Exposure to electric current, radiation and extreme ambient air temperature and pressure and Chapter 20: External causes of morbidity.
ICD-9-CM equivalent
Converter →- E902.8Accident due to changes in air pressure due to other specified causesapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about W99.XXXA
Is W99.XXXA billable?
- Yes. W99.XXXA is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
What does the "A" at the end of W99.XXXA mean?
- It is the 7th character for initial encounter. Per the official guidelines, use it while the patient is receiving active treatment for the condition.
Can W99.XXXA be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict W99.XXXA as a principal diagnosis.
Is W99.XXXA a CC or MCC?
- No. W99.XXXA is neither a CC nor an MCC under MS-DRG v44.0.
What is the ICD-9 code for W99.XXXA?
- The CMS General Equivalence Mappings map W99.XXXA to ICD-9-CM E902.8.