What You Can’t Smell Will Kill You

NY Times ^ | January 21, 2007 | LUCA TURIN

[beyond the sea]

I just figured that NYC pretty much always smelled like that. Actually NYC only smells like that because of the odors drifting across from New Jersey's gas refineries!!!

..... nah, smell drifting down from Chappaqua.

[philman_36]

I'm quite familiar with with H₂S. I've "worked under fresh air" for hours at a time on occasions too numerous to mention on a variety of dangerous gases.
We've got over a dozen petrochemical/chemical plants in the area and I've worked in most of them over the years.
With the petrochemical/chemical plants in New Jersey they could've had a release of some sort.
If the smell was lingering it probably wasn't H2S.
Lots of folks were saying they couldn't smell it after a while. As you stated...H₂S produces olfactory fatigue...thus after a while they "stopped smelling it".
Source of Manhattan Gas-Like Odor Is a Mystery
Almost as quickly as it came, the smell of gas left Manhattan and parts of New Jersey yesterday, leaving authorities no closer to determining where it came from.
Before the odor dissipated, several New York City agencies and the United States Coast Guard launched investigations and some train service was temporarily suspended. A number of buildings in Midtown turned off their HVAC systems to keep fresh air out, while others were evacuated, officials said.

Sample H2S MSDS
Above 200 ppm loss of smell is very rapid. Olfactory fatigue may also, reportedly, result from prolonged exposure to levels below 100 ppm. We have not observed this latter effect in normal outdoor operations and the normally associated chronic intermittent exposures resulting from handling routine small leakages from CLOSED systems. Users should beware however that in enclosed spaces, buildings etc. where concentrations may be relatively constant, olfactory acclimatization or fatigue will occur and rising concentrations may not be noticed in such cases.

[Ciexyz]

Thank goodness the news has been quiet about any more clusters of dead birds recently.