you are correct but the article you cite seems to be dated 2024...

AFAIK its a Belgian-Polish research activity at least since 2006, potentially other places have done this earlier:

https://www.gva.be/cnt/oid417904

Before this ozone peaks were being detected with clovers and gladiola's...

Can confirm, I live in a much smaller city and we do have a water treatment and monitoring plant that does the same.