If there is something you consider to be significant, or you want to stress that it isn’t petty and of little importance, you might use this expression in English; “it’s not to be sneezed at” or if you prefer “it’s not to be sniffed at”.
You might wonder why you would in any case want to sneeze or sniff at something. Why indeed! Well, we will start with the earliest possible explanation. To do so, we must travel back to Ancient Greece and the cult of the goddess Demeter (Δήμητρα). She was the goddess of agriculture and the harvest. In ancient times, people might dedicate a sneeze to her. A sudden sneeze may have been interpreted as containing a warning from Demeter to stay away from something. Therefore, something not to be sneezed at was something worthwhile.
The second explanation to be looked at takes us back only a short way – to 17th century Europe, and a craze for using snuff, a status symbol which was the province of the rich. Of course, snuff induced sneezing. And it didn’t take long for the wealthy to start sneezing to show their disdain for the matter at hand. Naturally, it arose from this that something not to be sneezed at was something of some significance.
It is interesting to note that in Polish people say “I sneeze at something” to indicate that it’s not worth anything, which is the direct opposite of the English expression; kicham na… – “I sneeze at…”.
Personally, I rather like the Spanish expression, which is used in the same circumstances as the English one. No es moco de pavo, which literally means “it’s not a turkey’s comb”.