An art installation in Spain is leaving visitors with itchy eyes, shortness of breath, and feeling sick.
The so-called pollution pods are replicating air quality in some of the world's most polluted cities.
The organisers say they're aiming to show the daily reality of millions of people living in the smoggiest parts of earth.
Visitors described the different cities:
(SOUNDBITE) (English) 21-YEAR-OLD AUSTRALIAN MEDICAL STUDENT JACQUELINE BRENHAUER, SAYING:
"So the first environment in which we were in was Norway which was the cleanest air so that was quite pleasant and then you go into London which you would expect it wouldn't be to bad but it is a funny smell and you feel a little bit dizzy and then you go into the next room which is New Delhi and everyone was covering their mouth and feeling quite sick and disorientated you know like covering and itchy nose, itchy eyes as well."
The installation is coinciding with UN climate talks in the Spanish capital.
It's aimed at injecting fresh momentum into the global fight against climate change.