I on occasion get the diesel smoke lingering in the garage (normally don't store my tractor in the garage) and have thought about having an exhaust fan that has an exhaust pipe plumbed to it, that only comes on when the garage door is open and exhausts to the outside. Could be switched to a timer that could be manually started when the diesel smoke is a problem as an alternative. the exhaust fan could keep clean air coming across the smoke detector that way, and not interfere with its performance when the garage door was closed. Also, wouldn't be something that would have to be "hooked up" every time exhausting fumes is needed.
About the fumes of the diesel being real deadly. Not too sure they are quite as deadly as one might think, or that some have been telling, because;
I tried to kill a racoon in a trap (wanted to preserve the hide) and put the trap in a 55 gal. drum, and piped the exhaust directly into the drum. At best, after more than a couple hours, the racoon was a bit lethargic, but in no way was it dead. I decided it was taking too long and getting expensive, although the racoon probably was becoming comatose, so I used the cheap .22 method.
I'm not recommending being in an unvented garage with diesel smoke, but dangerous? not very under 'normal' operating conditions, in my opinion.
