In this case, the "air" was a little thicker than usual!
An aeroplane was forced to make an emergency landing after the gas of 2,186 animals was mistaken for smoke in the cargo hold.
The Singapore Airlines Boeing 747-400 freighter plane, which was en-route from Adelaide, Australia to Kuala Lumpur in Malaysia, was diverted to Bali Denpasar on October 26 following the urgent announcement.
Upon landing, emergency services boarded the aircraft - which was carrying four crew members and the flock of goats- however reported that there was no trace of fire, heat, or smoke.
According to the Aviation Herald, The smoke indication alarm sounded as the result of exhaust gasses and manure produced by the animals on the plane.
There's more at the link.
I had no idea a Boeing 747 freighter could hold so many goats. I hope they issued gas masks to the crew - and to the ground staff who had to clean out the plane afterwards! I also hope the next cargoes to be flown on that particular aircraft weren't the kind that can pick up stray odors . . .