Indoor environment factor · measured in µg/m³
Nitrogen oxides (NOₓ)
Also: NOx, nitrogen oxide, oxides of nitrogen
Nitric oxide and nitrogen dioxide taken together, as the mixture that combustion actually produces. Instruments and regulations frequently report the sum, because the two interconvert in air and the split depends on how long ago the burning happened.
What it is
The sum exists because the two members of it are not stable relative to each other. A flame emits mostly nitric oxide; the room converts it to nitrogen dioxide over minutes; and the proportion at the moment of measurement depends on distance from the source, on ventilation and on what else the air contains. Reporting their sum removes that dependence and gives a stable measure of how much combustion took place.
It also loses what matters for health. The health-based guidelines are written for nitrogen dioxide, because that is the member with the documented airway effects, and a value for the sum cannot be compared against them.
Coridum therefore records the sum only where a study reported it as such, keeps it under this slug rather than converting it, and uses the narrower slug wherever the study measured one gas rather than both.
What the studies report
| Linked to | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Gestational diabetes | OR 1.07 (1.04–1.11) | pregnant women | systematic review and meta-analysis of 35 epidemiological studies (33 cohort, 1 cross-sectional, 1 case-control) covering 6,939,725 pregnant women | F-0082 Association of air pollution and fine particulate matter (PM… (2023) | machine |
Each row is one Finding — a sentence as printed in one study, recorded with its page in the Coridum Knowledge Base. Follow the Finding number for the exact wording and the citation. Checked says who verified the row: machine means every automatic check passed and the surrounding text was read; person means someone read the sentence in the document. Rows are re-checked by a person over time. The studies are curated in the Coridum Knowledge Base; the reading of them together is a Claim, shown separately.
Identifiers
- Molecular formula
- NOₓ
- MeSH
- D009589
Cite this page
Coridum Research. Nitrogen oxides (NOₓ). Coridum Knowledge G-0189, 16 September 2026. https://coridum.com/k/G-0189/