There were 2 other similar incidents in London and Canada not too long ago, both were also evacuations due to chemical smell and breathing difficulties, they were also both on the same day. Those were just mentioned in a few small articles and then written off as nothing of importance...

edit, articles:

http://www.bbc.co.uk/news/uk-england-london-37739046

http://www.dailystar.co.uk/news/latest-news/556510/british-airways-plane-grounded-vancouver-passengers-sick-hospital