I have seen style manuals suggest that there be no space between emdash and the surrounding words.
The following NY times article has spaces in the first sentence:
"An expression of concern by the environmental group Greenpeace about the carbon footprint was marred this week by real footprints — in a fragile, and restricted, landscape near the Nazca lines, ancient man-made designs etched in the Peruvian desert."
This despite there being an article in the same Ny times suggesting no space. What is correct?
http://opinionator.blogs.nytimes.com/2012/10/22/mad-dash/
First, make the thing the right way. There are a few ways to do it, but generally, on a keyboard, you can do as follows: previous word/no space/two hyphens/no space/following word. Word-processing programs turn the two hyphens into an unbroken line that’s roughly the width of a capital “M” — hence the official name of this punctuation mark, the em-dash. (Some publications, including this newspaper, add spaces around dashes.)