https://smogathon.com/
Smogathon 2019: Data hackathon, 7-8th December, Krakow.
Nov 18, 2019 - Smogathon 2019: Data hackathon, 7-8th December, Krakow. Prize pool: 125 000 PLN. Get a team together and create smog-fighting solutions.
datahackathondecember