Researchers at York University in Toronto have found that air quality monitoring networks contain many. This is a discovery that could allow monitoring of life on an unprecedented scale.
Since humans are animals like any other, their DNA can be captured. The method we use only looks for very small fragments of DNA. It's just enough to identify species, but nothing more. According to the researcher, the samples used do not identify the individuals present. "We could say humans were present," but nothing else, says Elizabeth Clare.