May a person daven in a NYC subway car that has a smelly person sitting there?

Question

There's a saying in NYC:

"If you're pregnant or elderly, you won't get a seat. But, if you smell bad, you can get a whole subway car."

Sadly, the number of (homeless, usually) smelly people found in the NYC subway is increasing. Shulchan Aruch O.C. 79:1 states that one needs to distance himself 4 amot from excrement. 79:8 says to distance oneself from smelly garbage. Most of the smelly people on the subway smell from B.O.; possibly from urine; possibly from alcohol and possibly from cigarette or "weed" smoke. It's neither of the above. Thus, I'm not sure if these rules apply to any type of these foul odors, and I couldn't infer that these apply to even a person that smells from excrement rather than excrement itself that came out of the person. (Some of them smell like garbage, BTW, but I wouldn't know if they smell from garbage.)

In many of the NYC subway cars, you cannot pass from one car to the next; the doors are locked. Let's say someone was davening, and a smelly person entered the subway car. Can he continue davening?

Thanks to @WhyEnBe who states that 4 amot = 8-10 feet. A NYC subway car is significantly longer than this. Technically, one could be sitting more than 4 amot away from the smelly person. However, as implied by my opening paragraph, the bad smell occupies the entire car, typically. So, I'm not sure if the halacha also applies to source of the bad smell being there regardless of the distance you may be from its source.

1/8/18 - Adding to this - Typical NYC subway elevators also smell from urine. Can one daven in there?

Answer 1

According to this it is permissible to pray next to a person with foul body odour, assuming that the smell is sweat, rather than "something sharp":

אם מדובר בריח של זיעה אין איסור, אלא אם כן מדובר במשהו חריף

This would presumably be based on Yerushalmi Shabbat (2:2) which states (see P'nei Moshe) that one may pray in the presence of עיטרן, a foul smelling tar, and that you shouldn't think that just because something smells bad that you must distance yourself from it.

The Hayei Adam (Vol. I: 3:12) generalises this Yerushalmi to state that (other than excrement) the only substance around which one may not pray, is that which became rotten, but something which is itself smelly is not a problem. Accordingly, if it is just the stench of sweat, it would be permissible to pray.

Nevertheless, it is good to be stringent to not pray around a distractingly bad smell (see Rambam's Hilkhot Tefilla 4:9 based on Eruvin 65a (which mentions the smell of alcohol), and the Meiri's commentary there).

Similarly, R. Adir Kohen writes here that since it is permissible to pray in the presence of things which naturally smell bad, it is permissible to pray around people who reek of sweat. However, if the smell is distractingly bad, it is appropriate to be stringent to not pray there.

Regarding prayer around urine, Berakhot (25a) is explicit that prayer around urine is forbidden, although in cases of doubt whether there is urine, one may pray (see Rambam's Hilkhot Tefilla 3:15).

Significantly the Shulhan Arukh (OH 79:8) does state that it is forbidden to pray around smelly garbage.