Data table · version 1.0 · Extracted from published sources
Indoor air quality limits by jurisdiction
Exposure limits and guideline values for the nine factors and parameters Coridum measures — particulate matter, VOCs, CO₂, carbon monoxide, humidity, mould, ozone, formaldehyde and benzene — compared across the World Health Organization, the European Union and, as they are compiled, Slovakia, the United Arab Emirates and Hong Kong.
A single reference table of the numbers that define “too much” for the factors and parameters Coridum measures. Every row names its source and states whether the value is an indoor guideline, an ambient (outdoor) standard applied by analogy, or a product-emission limit. Version 1.0 covers the World Health Organization and the European Union; Slovak, UAE and Hong Kong values are being verified against the primary documents and will be added in version 1.1.
Particles and gases
| Factor | Jurisdiction | Value | Averaging time | Scope | Source |
|---|---|---|---|---|---|
| PM₂.₅ | WHO | 5 µg/m³ · 15 µg/m³ | annual · 24 h | guideline | WHO AQG 2021 |
| PM₂.₅ | EU | 10 µg/m³ · 25 µg/m³ | annual · 24 h | ambient, from 2030 | Directive (EU) 2024/2881 |
| PM₁₀ | WHO | 15 µg/m³ · 45 µg/m³ | annual · 24 h | guideline | WHO AQG 2021 |
| PM₁₀ | EU | 20 µg/m³ · 45 µg/m³ | annual · 24 h | ambient, from 2030 | Directive (EU) 2024/2881 |
| Ozone | WHO | 100 µg/m³ · 60 µg/m³ | 8 h daily max · peak season | guideline | WHO AQG 2021 |
| Ozone | EU | 120 µg/m³ | 8 h daily max | ambient target | Directive (EU) 2024/2881 |
| Carbon monoxide | WHO | 100 · 35 · 10 · 7 mg/m³ | 15 min · 1 h · 8 h · 24 h | indoor guideline | WHO IAQ 2010 |
| Formaldehyde | WHO | 0.1 mg/m³ | 30 min | indoor guideline | WHO IAQ 2010 |
| Formaldehyde | EU | 0.062 mg/m³ (articles) · 0.080 mg/m³ (furniture, wood-based) | chamber test | product emission | Regulation (EU) 2023/1464 |
| Benzene | WHO | no safe level; 1.7 µg/m³ ≈ 1 in 100 000 lifetime risk | lifetime | indoor guideline | WHO IAQ 2010 |
| Benzene | EU | 3.4 µg/m³ (from 2030; currently 5) | annual | ambient | Directive (EU) 2024/2881 |
| Volatile organic compounds (TVOC) | WHO / EU | no TVOC limit; compound-specific values | — | — | WHO IAQ 2010 |
Ventilation and moisture
| Parameter | Body | Value | Meaning | Source |
|---|---|---|---|---|
| Carbon dioxide | ASHRAE 62.1 | ≈ 700 ppm above outdoor (≈ 1100 ppm) | design reference | ASHRAE 62.1 |
| Carbon dioxide | Germany, UBA | < 1000 · 1000–2000 · > 2000 ppm | harmless · elevated · unacceptable | UBA 2008 |
| Carbon dioxide | UK, BB101 | 1000 ppm (mechanical) · 1500 ppm (natural) | classroom daily average | BB101 2018 |
| Relative humidity | ASHRAE 62.1 | ≤ 65 % | occupied spaces | ASHRAE 62.1 |
| Relative humidity | WHO | no numeric limit | prevent persistent dampness | WHO 2009 |
| Mould | WHO | no numeric limit | prevent or remediate growth | WHO 2009 |
Notation
Values on this page follow the International System of Units (SI Brochure, 9th edition) and the IUPAC Green Book (CKB 1705, sections 3.10 and 4.1): a space between number and unit symbol (100 µg/m³, 20 °C, 50 %), digits grouped only from five digits upward and then by a thin space, never a comma, chemical formulae with subscripts (CO₂, PM₂.₅). The unit ppm is kept where the source document uses it (WHO, ASHRAE); the Green Book recommends the unambiguous µmol/mol, and 1 ppm = 1 µmol/mol for gases. In the CSV file the unit column uses the Unified Code for Units of Measure (UCUM, version 2.2, CKB 1708) so that it can be read by software without special characters: ug/m3, mg/m3, ppm, Bq/m3, %, Cel. The pollutant column name is kept in version 1.0 for compatibility and will be renamed factor in version 1.1.
Version history
- 1.0 (5 September 2026) — WHO and EU values for nine factors and parameters; ASHRAE, UBA and BB101 reference values for CO₂ and humidity. Same day, before any external use: unit code for humidity corrected from
% RHto%(UCUM); no values changed. - Planned 1.1 — Slovak decree values, Dubai Municipality indoor air quality standard, Hong Kong IAQ Objectives (2019); column
pollutantrenamedfactor.
Frequently asked questions
Why are some rows outdoor (ambient) limits?
Because for several factors no jurisdiction sets a binding indoor limit. Ambient standards are the values most often applied indoors by analogy; the scope column makes the distinction explicit.
Which value should I use for my building?
For health protection, the WHO guideline. For compliance, the rule of the jurisdiction the building is in. Where the two differ, the WHO value is almost always the stricter.
How is this table maintained?
Each row carries its source document. The table is versioned; when a value changes or a jurisdiction is added, the version number increases and the change is noted below.
Sources
- WHO global air quality guidelines. World Health Organization, 2021.
- WHO guidelines for indoor air quality: selected pollutants. WHO Regional Office for Europe, 2010.
- WHO guidelines for indoor air quality: dampness and mould. WHO Regional Office for Europe, 2009.
- Directive (EU) 2024/2881 on ambient air quality and cleaner air for Europe.
- Commission Regulation (EU) 2023/1464 (REACH Annex XVII, formaldehyde).
- ANSI/ASHRAE Standards 62.1 and 55.
- UK Department for Education, Building Bulletin 101, 2018.
- Umweltbundesamt, Gesundheitliche Bewertung von Kohlendioxid in der Innenraumluft, 2008.
- Quantities, Units and Symbols in Physical Chemistry (IUPAC Green Book), Third Edition (2007). IUPAC / RSC Publishing. doi:10.1039/9781847557889 CKB 1705
- The Unified Code for Units of Measure (UCUM) - specification, version 2.2 (2024). UCUM Organization / Regenstrief Institute. CKB 1708
CKB = document number in the Coridum Knowledge Base, our curated library of peer-reviewed studies. Follow the DOI for the original paper.
Cite this page
Coridum Research. Indoor air quality limits by jurisdiction (v1.0). Coridum Knowledge D-0001, 5 September 2026. https://coridum.com/k/D-0001/