This might be the question we get asked the most. And I understand why: most of the time, our Air Quality Index (AQI) is very different from the local government source (EPA in the US, Defra in the UK, etc.). Would you like to know why?
Raw vs Right Data
First, we do not limit our air quality analysis to government monitoring stations, we add additional layers of data into our algorithms to provide you a more accurate air pollution reading at your exact location. Local sources (and most air quality apps) only show air quality data from the monitoring station the closest to you, which can be 1.5, 6 or 12 miles away. Yet, in reality, air pollution can vary dramatically from one city block to another and is highly impacted by weather conditions. Now you understand the lack of accuracy of local sources. In contrast, BreezoMeter's methods are more accurate and take into account most factors impacting air quality and flow dispersion into the calculation. This is the first reason why you will see such a difference between our reports and local sources or other applications.
The BAQI: Origins
When we started BreezoMeter, there was no standardized approach to providing air quality indexes across the world. Air quality indexes are usually (very) different between countries. Some AQIs are derived from health recommendations and/or epidemiological studies, some from emission standards, some from political consideration, etc.
We found this fact disturbing and difficult to apprehend. For us, it was a real blocker to making air quality visible, understandable and to help populations react to pollution events.
The BAQI: Methodology
Hence, we invested a lot of time and resources into researching air quality indexes and developing one unified global index, ranging from 0 (worst) to 100 (best), with 5 levels. We called it the BAQI (BreezoMeter’s Air Quality Index). The BAQI was built by studying AQIs of dozens of countries and publications from the US EPA, the WHO and additional scientific research. Of these standards, only those derived from health recommendations were taken into account - air quality information needs to be impactful and actionable. Efforts were made to minimize the effect of political considerations and external influences. The BAQI can be summarized as an aggregate of national AQIs, with the stricter approach chosen when there was wide discrepancies between pre-existing AQIs and research.
Now we can all objectively know how good the air we breathe is.
As some of you prefer to view the local AQI, we always provide in our API and Apps the local air quality index as defined by your country's government. Note, however, that the data provided is still the result of our complex spatial computations, rather than the more widespread simplistic closest-station approach. Expect different values compared to local sources.