Fumes are best avoided. They contain mercury.
True story: I was testing the quality of the water from a property I was thinking of buying and got a hit for high levels of mercury. I called the test manufacturer and asked for a few more tests to confirm the levels and the guy asks "done any soldering in the area within the last TWO WEEKS", I had been soldering the taillight / trailer connections on my van about two or three weeks prior and that was enough to leave detectable levels of mercury lingering in the undercover outdoor area where I conducted the tests.