Any information on (one or more) gas attacks in Vietnam in 2000?

Question

While staying in a Hanoy disco in 2000 there was a sudden rush to the exit with people pointing to their nose; when I also approached the exit I found myself unable to breath until I reached for the outside where there was no police or anything but volunteers to help.

I searched on the net but I found nothing possibly because I was the single westerner there; this even if the confidence displayed by the local bystanders hinted to the non exceptionality of the event and so others could have experienced the same occurrence.

Has anybody got any information on the kind of gas used, authors or anything?

Answer 1

There is no information available on this.  Check with the local police.