Exposure to other man-made environmental factors (W99) ICD-10-CM
The W99 code range covers exposure to other man-made environmental factors with 4 ICD-10-CM diagnosis codes. 3 of them are billable and valid for claim submission in fiscal year 2027, and the category headers group them but cannot themselves be billed.
7th Character Note
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
- The appropriate 7th character is to be added to code W99
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
- A - initial encounter
- D - subsequent encounter
- S - sequela
Codes in the W99 Range 4 codes · 3 billable
About the W99 Code Range
A sudden loss of aircraft cabin pressure or a pressure change while diving is an example of the exposure described by W99.
Its subdivisions distinguish an initial encounter (W99.XXXA), a subsequent encounter (W99.XXXD), and a sequela, or later effect (W99.XXXS). The final character marks that distinction.
Questions About This Page
How many billable codes are in the W99 range?
Of the 4 codes in this range, 3 are billable and valid for claim submission from October 1, 2026 through September 30, 2027. Category header codes group them but cannot be reported on claims.
What does the W99 range classify?
The range classifies exposure to other man-made environmental factors. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
