Usage notice and disclaimer

• Crowdsourced, not official. Readings come from consumer-grade sensors owned and operated by volunteers. This is not government monitoring data, and openaqi is not affiliated with any environmental agency. For official measurements, and for anything with legal weight, consult your national or local environmental authority.
• Unvalidated at publication. Readings appear as soon as they arrive. They are not reviewed, calibrated against a reference instrument, or quality-assured, and they may be corrected or removed at any time, without notice.
• Individual sensors vary, sometimes wildly. Low-cost sensors drift as they age, read differently in high humidity, and report whatever is in front of them — which may be a kitchen, a wood stove, a construction site, or a busy road four metres away. Two sensors in the same area can disagree substantially, and neither is necessarily wrong about its own position.
• Areas, not addresses. Every reading is aggregated into a cell of roughly 5 km². A cell average can hide a great deal of variation inside it, and it is never a measurement of the air at any particular street or building.
• Coverage is uneven. A cell with one contributing sensor is one person's reading, not a survey. An area with no colour has no contributors — it does not mean the air there is clean.

Colours are anchored to published health thresholds, never to the range of values currently on screen. A relative scale would paint the worst cell red on a day when every reading is fine, which on a public map is a false alarm rather than a cosmetic problem. Each metric cites the standard it is graded against:

• AQIUS EPA AQI categories (sensor range 0-500)
• VOCUniFi spec: VOC Index 1-500 (Sensirion scale)
• PM1.0No PM1 standard — PM2.5 bands used as a proxy
• PM2.5US EPA 24-hour PM2.5 breakpoints
• PM4.0No PM4 standard — PM10 bands used as a proxy
• PM10US EPA 24-hour PM10 breakpoints
• CO₂ASHRAE / common IAQ guidance (sensor range 0-40,000 ppm)
• eCO₂Estimated value — not a measurement. CO₂ bands shown for orientation only
• COUS EPA AQI 8-hour CO breakpoints
• NO₂US EPA AQI 1-hour NO₂ breakpoints
• OzoneUS EPA AQI 8-hour ozone breakpoints
• SO₂US EPA AQI 1-hour SO₂ breakpoints
• H₂SWHO air quality guideline, 24-hour (150 µg/m³ ≈ 107 ppb)
• FormaldehydeWHO indoor guideline, 30-minute (100 µg/m³ ≈ 81 ppb)
• BenzeneEU Directive 2008/50/EC annual limit 5 µg/m³ (~1.6 ppb); WHO states no safe level
• RadonWHO Handbook on Indoor Radon (reference level 100 Bq/m³; US EPA action level 148)
• HumidityEPA / ASHRAE indoor humidity guidance
• NoiseWHO Environmental Noise Guidelines (road traffic, Lden 53 dB)
• UV indexWHO Global Solar UV Index

NOx index, PC0.3, PC0.5, PC1.0, PC2.5, PC5.0, PC10, NO, NOx, NH₃, TVOC, TVOC (conc.), Temperature, Pressure, Light are shown without a severity band. Where no published health threshold exists, openaqi reports the value and says so, rather than inventing a scale.

Nothing on this site is medical, health, safety, environmental, legal or financial advice. In particular, do not use openaqi data as the basis for:

• medical or health decisions, for yourself or anyone else;
• regulatory compliance, enforcement, permitting, or any official reporting;
• legal proceedings, insurance claims, property valuation, or tenancy and employment decisions;
• emergency or evacuation decisions during a fire, chemical release or similar event — follow the instructions of your local authorities, who have instruments and obligations that this project does not.

All reasonable care has been taken in building this service, but the data and the site are provided “as is” and “as available”, without warranty of any kind, express or implied, including accuracy, completeness, timeliness, or fitness for any particular purpose.

To the fullest extent permitted by law, openaqi and its contributors accept no liability in contract, tort or otherwise for any loss, injury or damage arising directly or indirectly from the use of this site, from any information it contains, or from any action taken as a result. Availability is not guaranteed and the service may change or stop at any time.

Raw sensor coordinates are used once, to work out which ~5 km cell a station falls in, and are never returned by any public endpoint. The readings table has no location column at all — that is a property of the schema, not a policy that could quietly change. Sensors are labelled by a derived identifier rather than by the name their owner gave them.

If you contribute readings, you are responsible for having the right to publish measurements taken at your location. You can stop at any time; ask and your data will be removed.

If you use openaqi data elsewhere, attribute it to openaqi contributors with a link back, and carry this notice with it — in particular, do not present these readings as official, reference-grade or validated measurements. Please do not scrape the site; use the API so the load is visible and can be kept working for everyone.

This notice may change as the project does. Material changes will be noted in the project's public repository history rather than applied silently.