I think it depends on use cases and advancements in our understanding of time's effect on the DNA captured.
I.e. I could imagine that in the not too distant future, we know that DNA in air (exposed to sunlight) degrades at a certain percentage over time, and therefore could be used to determine if a person was near a given location recently. Sort of like carbon dating.
You could imagine law enforcement using this as a tool to find suspects: Drive around with a device that constantly captures air and checks it for the DNA of a suspect (which could have been found at the scene via other, more traditional methods) and then allows them to narrow down a persons location.
I.e. I could imagine that in the not too distant future, we know that DNA in air (exposed to sunlight) degrades at a certain percentage over time, and therefore could be used to determine if a person was near a given location recently. Sort of like carbon dating.
You could imagine law enforcement using this as a tool to find suspects: Drive around with a device that constantly captures air and checks it for the DNA of a suspect (which could have been found at the scene via other, more traditional methods) and then allows them to narrow down a persons location.