On Monday we told you that ingesting just three teaspoons of Rio's water would make you almost certain of contracting a virus.
But now it seems that Rio's air is actually worse than its water - that's some pretty bad pollution.
Testing by news agency Reuters and the Brazilian government found that the city's air has consistently been above World Health Organisation limits for particulate matter.
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In fact, the contamination breached WHO levels in 2009, when the city was given the green light to host the games - and it's been over the limit every year since.
Two-thirds of the pollution caused comes from the 2.7 million cars on Rio's roads - pollution which contributes to thousands of deaths each year.
The alarming levels of contamination mean that Rio is among the dirtiest cities to host the Olympic Games, along with Beijing, which played host in 2008.
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So basically, the advice for athletes and tourists alike in Rio: don't put your head under water and don't breathe. Simple, right?
(H/T The Metro)