Murray Leinster was at one time known as "The Dean of Science Fiction," having started writing the stuff before there was any such thing and having continued to write it well past the middle of the 20th century. He wrote a little of everything, including what I'd call horror SF, like this novel that capitalizes on the '50s monster craze. It's a wonder that American-International didn't latch onto this book for a quick B&W cheapie with Ray Milland. It has everything: a small cast, a threat to all life on earth, and invisible monsters, which would have been a huge plus. You can't have a cheaper monster for film than an invisible one.
No doubt current readers would find the book hopelessly dated both in style and content. Leinster begins with eight or so pages of no dialogue, and when the dialogue comes, it's nearly always tagged (at least twice in the book, someone utters something zesfully). Leinster even uses passive voice. He does plenty of telling rather than showing. Some of the phrasing, maybe more than some, is pretty old-fashioned.
None of that bothers me at all, of course. I have no trouble reading books from another era and accepting their various styles. I can read Dickens with pleasure, and Shakespeare too, not that I'm claiming Leinster's in their league. (I sometimes think that when we complain something is "dated" the comment says more about us than about the material.)
As for the plot, well, it's about these sentient gases that started killing animals and are now killing humans. It's quite likely that these are the creatures that our ancestors thought of as demons, and for some reason they've suddenly started to reproduce at an incredible rapid rate. They're discovered by an oddly assorted group, and naturally no one believes them, not even when the deaths begin to multiply alarmingly. It's all fairly ridiculous, but Leinster manages to make it almost believable. I'm sure I must have read this when it first appeared back in 1958, but I didn't remember. It was fun and fast, and I'm glad I read it again. After all, how many books do you read in which smoking can save your life?