If the air is healthy enough for people to live in Rio, it is healthy enough to host the Olympics. The Olympics is a two-week event. Given that the air quality is not the best, it will not do anyone permanent damage to the athletes, coaches and fans for their two week stay there. For if the air quality is that bad that a two week stay can cause permanent damage, the issue should have been brought up way before the Olympics were hosted in Rio. As world citizens, we need to care about the Rio residents beyond a sporting event.
The Zika virus is just that, a virus. It's most well-known side effect are horrible birth defects but the Zika virus also causes flu-like symptoms which no one enjoys. How can athletes perform at their best when they have a large probability of becoming infected? How can fans come out to watch the games and not wonder if today is the day they develop the virus?
Rio is not only dangerous, but it is extremely polluted. The city has a terrible polution problem and the pollution is going to cause terrible health problems for the people who stay. The atletes are sure to be effected for a long time after the games are over and they go home.
No, the air in Rio is not suitable enough for the city to host the Olympics. The city of Rio suffers from many issues that make it a danger to its own citizens. Examples of these are pollution, overcrowding, and a general lack of important societal infrastructure. The pollution and overcrowding pose extreme risks to public health as these things account for poor air quality in Rio. Until these problems are solved, Rio should not host any event, let alone the Olympics.