2026 ICD-10-CM Diagnosis Code T59.91XSToxic effect of unspecified gases, fumes and vapors, accidental (unintentional), sequela
T59.91XS is a billable ICD-10-CM diagnosis code for toxic effect of unspecified gases, fumes and vapors, accidental (unintentional), sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 922 through 923. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Poisoning/toxic effect/adverse effects/underdosing, sequela.
Code Identity
Code Classification
Present on Admission (POA)Billing
T59.91XS is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Accidental poisoning by gaseous substance
- Accidental poisoning by gases or fumes on ship
- Accidental poisoning by gases or fumes on ship, docker or stevedore injured
- Accidental poisoning by gases or fumes on ship, occupant of small powered boat injured
- Accidental poisoning by gases or fumes on ship, occupant of small unpowered boat injured
- Accidental poisoning by gases or fumes on ship, swimmer injured
- Acute bronchiolitis
- Acute bronchiolitis caused by chemical fumes
- Acute bronchitis caused by chemical fumes
- Acute edema
- Acute pneumonitis caused by chemical fumes
- Acute pulmonary alveolitis caused by chemical fumes
- Acute pulmonary edema
- Acute pulmonary edema caused by fume
- Acute pulmonary edema caused by vapor
- Asphyxiation by environmental toxic gas
- Brass-founders' fever
- Bronchitis and pneumonitis caused by chemical fumes
- Bronchitis caused by chemical fumes
- Bronchitis caused by vapor
- Chronic bronchiolitis
- Chronic emphysema caused by chemical fumes
- Chronic emphysema caused by vapor
- Chronic fibrosis of lung
- Chronic obliterative bronchiolitis
- Chronic obliterative bronchiolitis caused by chemical fumes
- Chronic obliterative bronchiolitis caused by vapor
- Chronic pulmonary fibrosis caused by vapor
- Chronic respiratory condition caused by fumes
- Chronic respiratory condition caused by vapor
- Disorder due to vaping
- Inflammation of upper respiratory tract caused by fumes
- Inflammation of upper respiratory tract caused by vapor
- Inhalation burn due to hot gas
- Inhalation injury
- Injury due to legal intervention by asphyxiation by gas
- Injury due to legal intervention by gas
- Injury due to legal intervention by poisoning by gas
- Injury due to poison gas weapon
- Interstitial pulmonary fibrosis due to inhalation of substance
- Metal fever
- Pneumonitis caused by fumes
- Pneumonitis caused by vapor
- Poisoning by fumes
- Poisoning caused by gaseous substance
- Poisoning due to crowd control gas
- Poisoning due to irritant gas
- Pulmonary edema caused by chemical fumes
- Respiratory condition caused by chemical fumes
- Respiratory condition caused by chemical fumes and vapor
- Respiratory condition caused by vapor
- Subacute obliterative bronchiolitis
- Subacute obliterative bronchiolitis caused by chemical fumes
- Subacute obliterative bronchiolitis caused by vapor
- Toxic emphysema
- Toxic inhalation injury
- Toxic inhalation-induced febrile illness
- Toxic pulmonary edema
- War injury caused by gas
- War injury due to fumes
- War injury due to gases, fumes and chemicals
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Toxic effect of other gases, fumes and vapors (T59). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Acute Bronchiolitis
acute inflammation of the bronchioles usually caused by the respiratory syncytial virus.
Table of Drugs and ChemicalsClinical
Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.
| Substance | Accidental | Self-harm | Assault | Undetermined | Adverse Effect | Underdosing |
|---|---|---|---|---|---|---|
| Fumes (from) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::carbon monoxide | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::charcoal (domestic use) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::chloroform | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::coke (in domestic stoves, fireplaces) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::corrosive NEC | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::ether | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::freons | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::hydrocarbons | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::hydrocarbons::petroleum (liquefied) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::hydrocarbons::petroleum (liquefied)::distributed through pipes (pure or mixed with air) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::lead | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::metal | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::nitrogen dioxide | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::pesticides | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::petroleum (liquefied) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::petroleum (liquefied)::distributed through pipes (pure or mixed with air) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::polyester | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::specified source NEC [See Also: substance specified] | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Fumes (from)::sulfur dioxide | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::acetylene | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::acetylene::incomplete combustion of | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::air contaminants, source or type not specified | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::anesthetic | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::blast furnace | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::butane | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::carbon monoxide | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::chlorine | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::coal | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::cyanide | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::dicyanogen | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::domestic | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::exhaust | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::from utility (for cooking, heating, or lighting) (after combustion) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::from utility (for cooking, heating, or lighting) (after combustion)::prior to combustion | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::from wood- or coal-burning stove or fireplace | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::fuel (domestic use) (after combustion) [See Also: Carbon, monoxide, fuel] | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::fuel (domestic use) (after combustion) [See Also: Carbon, monoxide, fuel]::industrial use | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::fuel (domestic use) (after combustion) [See Also: Carbon, monoxide, fuel]::prior to combustion | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::fuel (domestic use) (after combustion) [See Also: Carbon, monoxide, fuel]::utility | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::fuel (domestic use) (after combustion) [See Also: Carbon, monoxide, fuel]::utility::in mobile container | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::fuel (domestic use) (after combustion) [See Also: Carbon, monoxide, fuel]::utility::incomplete combustion of | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::fuel (domestic use) (after combustion) [See Also: Carbon, monoxide, fuel]::utility::piped (natural) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::garage | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::hydrocarbon NEC | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::hydrocarbon NEC::incomplete combustion of | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::hydrocarbon NEC::liquefied | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::hydrocarbon NEC::liquefied::piped | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::hydrocyanic acid | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::illuminating (after combustion) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::illuminating (after combustion)::prior to combustion | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::incomplete combustion, any | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::kiln | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::lacrimogenic | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::liquefied petroleum | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::marsh | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::motor exhaust, not in transit | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::mustard, not in war | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::natural | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::nerve, not in war | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::oil | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::petroleum (liquefied) (distributed in mobile containers) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::petroleum (liquefied) (distributed in mobile containers)::piped (pure or mixed with air) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::piped (manufactured) (natural) NEC | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::producer | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::propane | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::refrigerant (chlorofluoro-carbon) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::refrigerant (chlorofluoro-carbon)::not chlorofluoro-carbon | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::sewer | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::specified source NEC | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::stove (after combustion) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::stove (after combustion)::prior to combustion | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::tear | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::therapeutic | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::utility (for cooking, heating, or lighting) (piped) NEC | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::utility (for cooking, heating, or lighting) (piped) NEC::in mobile container | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::utility (for cooking, heating, or lighting) (piped) NEC::incomplete combustion of | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::utility (for cooking, heating, or lighting) (piped) NEC::piped (natural) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::water | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Gas NEC::water::incomplete combustion of | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Lung irritant (gas) NEC | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Nerve gas, not in war | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Sewer gas | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Vapor [See Also: Gas] | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Vapor [See Also: Gas]::kiln (carbon monoxide) | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Vapor [See Also: Gas]::lead | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
| Vapor [See Also: Gas]::specified source NEC | T59.91 | T59.92 | T59.93 | T59.94 | – | – |
Patient EducationClinical
Poisoning
A poison is any substance that is harmful to your body. You might swallow it, inhale it, inject it, or absorb it through your skin. Any substance can be poisonous if too much is taken. Poisons can include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T59.91XS to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T59.91XSOverview
Is T59.91XS a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of unspecified gases, fumes and vapors, accidental (unintentional), sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T59.91XS mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the toxic effect of unspecified gases, fumes and vapors, accidental (unintentional) itself has resolved, not the original event.
What MS-DRG does T59.91XS group to?
When toxic effect of unspecified gases, fumes and vapors, accidental (unintentional), sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.
Is T59.91XS exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for toxic effect of unspecified gases, fumes and vapors, accidental (unintentional), sequela on inpatient claims.
What is the ICD-9 equivalent of T59.91XS?
Under the General Equivalence Mappings, toxic effect of unspecified gases, fumes and vapors, accidental (unintentional), sequela converts to ICD-9-CM 909.1 (late eff nonmed substanc). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
