Your first link is to a Canadian government website. According to Canadian law:
Unless otherwise specified, copyright in works prepared by or under the direction or control of the government of Canada (Crown) is owned by the Crown.
Source: http://publications.gc.ca/site/eng/ccl/aboutCopyright.html#e......

The rules are different for US government publications. Works of the United States Government are (in most cases) in the public domain. Note that I'm writing about federal government works. State and local governments may and often do claim copyright in their publications.

I'm of the opinion that it's almost always better to quote brief excerpts and provide a link, rather than to risk accidentally using intellectual property to which I am not entitled.

Well, that explains it I guess although I don't know why any gov't would not want information impacting public safety as widely disseminated as possible and waive any copyrights. So I am of the opinion that if human health and safety is involved, I'd rather err on the side of posting as much information as possible than risk someone else's well-being.