I am using the data from the EPA (<a href="http:&#x2F;&#x2F;www.airnow.gov&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.airnow.gov&#x2F;</a>).<p>I also built the API to get the data from that source. So to add more countries I would need to get the data from others environmental agencies and populate my database. It is totally doable, fortunately the data from different agencies are often using the same notation standard. However the APIs are most of the time slightly different and it would take some time.<p>On the technical point of view, I am using Compose.io as my database is MongoDB and I already need to store 700,000 documents (10 moving days) which is not so much but takes some space anyway and cost me money every month ($36). So if I want to add more data and keep the app free I would need to change my database provider or even my database. I would love to do it, I am thinking of Postgres on AWS but I don&#x27;t have the time right now.