O'Hare Air is a company for bottled air, founded by Aloysius O'Hare. It exploits the enviromental collapse by selling bottled air to the people of Thneedville. It is one of the most-liked products in Thneedville. The business was shut down when the people of Thneedville decided to have real oxygen from trees rather than air from bottles when they learned from Ted that things in Thneedville were not as they should be.
The founder, Aloysius O'Hare, started as a maintanance man, and was repairing the rusty Thneed signs outside the Once-ler factory one day with an unnamed partner. His partner observed that the Thneed was a "million dollar invention" and so speculated who would be the next to come up with such an idea. Inspired by this comment and the smoggy air surrounding him, O'Hare started his own company, O'Hare Air, which sold fresh air to the citizens of Thneedville. To keep profiting off the air, O'Hare had walls built around the city, making an airtight seal between the smoggy air outside and the fresher air inside, ensuring citizens would have to continually buy his fresh air in order to breathe.
Eventually, in the climax of the film, the walls are pushed down by an earthmower (driven by Ted Wiggins) and the wasteland outside is revealed to Thneedville. O'Hare sings "Let it Die", basically meaning that it doesn't matter, and then proceeds to think of O'Hare Air instead of the city of which he is the mayor. Cy berates him, the crowd defies him, and his henchmen expel him and his company from their city.
- O'Hare Air might be based on the large demands for bottled water.