For New York readers, here is a helpful guide to knowing whether you may have contracted Ebola on a subway from Forbes' Dan Diamond.
The graphic is funny but the point is serious: it is very hard to contract Ebola, as Julia Belluz explains here. An especially relevant section:
Amid the panic and fear about Ebola sweeping the US, let's be clear about one fact: as far as we know, two nurses who cared for [Thomas Duncan, the Liberian patient treated in Dallas who died] got the virus - but no one else. Not the passengers who sat next to Duncan on his flights or touched the same surfaces as him in airports.
Most importantly, his fiance, Louise Troh, didn't catch the virus either. She shared a cramped apartment with him and several other family members while he was already contagious, and then stayed in the same contaminated space, cooped up for days in a quarantine, after Duncan was admitted to hospital.
So far, all these people have been declared virus free. And the dozens of suspected cases of Ebola across the US have turned out to be negative, except for three - Duncan and his two nurses, Amber Vinson and Nina Pham. The fact that they got sick while caring for Duncan should also remind us of the science of this virus: that fits what we know of the science of the virus, which is that people are most contagious late in the infection.
If you're looking for more specific information about how, exactly, one can catch Ebola while in transit, check out our explainer on how Ebola can be transmitted on a plane — it works great for understanding the risk (or lack thereof) of riding subways as well.