The AirNow API has CORS disabled to prevent direct website access to the API. Currently, there is no plan to enable CORS , so we recommend that users who want to use the data provided by the API in a web application take an alternative approach.
For instance, a user can download the data on a schedule to their own API and database solution or store the data in the cloud. For websites with minimal traffic, Amazon AWS S3’s free tier or Google’s Cloud Storage are good no-cost solutions.