W99 vs Y84.2
W99 (Exposure to other man-made environmental factors) compared with Y84.2 (Radiological procedure and radiotherapy as the cause of abnormal reaction of the patient, or of later complication, without mention of misadventure at the time of the procedure), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. W99 carries an Excludes1 note covering Y84.2: “radiological procedure and radiotherapy (Y84.2)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| W99Exposure to other man-made environmental factors | Y84.2Radiological procedure and radiotherapy as the cause of abnormal reaction of the patient, or of later complication, without mention of misadventure at the time of the procedure | |
|---|---|---|
| Billing status | Non-billable header | Billable |
| Classification | V00-Y99 — External Causes of Morbidity (V00-Y99) | V00-Y99 — External Causes of Morbidity (V00-Y99) |
| Definition | Exposure to other man-made environmental factors is a non-billable ICD-10-CM category code (W99). | Radiological procedure and radiotherapy as the cause of abnormal reaction of the patient, or of later complication, without mention of misadventure at the time of the procedure is a billable ICD-10-CM diagnosis code (Y84.2). |
| 7th character | The appropriate 7th character is to be added to code W99 | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources