According to the study, you have a higher chance of dying if you have lived for 10 or more years in an area with one microgram per cubic meter of pollution more than someone else who lived with that much less pollution.

Does that means countries like Italy, US, Germany, Spain and UK have the worst air pollution?

I wouldn't agree with that.

The last time I checked, I think Bangladesh, India was on the top list of the world most polluted countries. I agree that people can die from dehydration, but if the pollution issue has a huge effect on covid19 patients, then countries like bangladesh, and others listed in this link should at the top list of covid19 fatality.
https://www.iqair.com/world-most-polluted-countries

This is just my opinion, I might be wrong. I'm new on hive. Did my first post yesterday. Thank you.