If someone ever grills food around you, you will breath carcinogens.

If you eat a piece of lunchmeat, you've eaten a carcinogen.

If you've ever tasted alcohol, you've drank straight carcinogenic liquid.

If you've ever driven a car or been near a road, you've breathed in dozens of carcinogens.

If you've ever been in a city, you've smelled the sweet smell of industrial heavy metals, which are..... Wait for it.... Carcinogens.

In fact, it's impossible to avoid carcinogens. That's why we have medical science which has come so far as to determine how many the human body can handle before it risking health.

And, so far, medical science has not been able to link outside second-hand smoke to cancer or other problems, especially short-term exposure.