According to a Swiss study published in the renowned journal Nicotine and Tobacco Research, exhaled vapor evaporates in seconds and indoor air quality returns to baseline values almost immediately.
Compare that with exhaled tobacco smoke, which adversely affects indoor air quality for 30 - 45 minutes.
The study's senior author, Dr. Grant O'Connell stated, "This data adds to the growing body of evidence that vaping indoors is unlikely to pose an air quality issue."
In 2017, the California Dept. of Public Health (CDPH) conducted a similar study, focusing on air samples from inside vape shops (where there is obviously a lot of vaping happening.) The results were the same as the Swiss study, where levels of toxic substances in the the air were found to be "insignificant."
Not surprisingly, because the results were contrary to what the CDPH was trying to prove, the findings of the study were never officially published.