Open Weather Map (OWM) Air Quality Index
The scale ranges from 1 to 5:
1 = Good
2 = Fair
3 = Moderate
4 = Poor
5 = Very Poor
As with other OWM data, this may or may not work, depending on your API key validity, which depends on the evolving OWM policies.
Currently, it should work with a “Current weather and forecasts collection” key created before August 2022, or with a “One Call by Call” subscription (free up to 1000 API calls per day – Instinct Pro will not exceed 300 calls per day).