(The Center Square) – An environmentalist and Chicago professor says asthma cases and respiratory disease cases are on the rise, possibly due to the Chicago Park district cutting down mature trees.

Environmentalist groups are calling for a Chicago Lakefront National park designation amidst the park district’s plans to cut more trees down for projects associated with the Redefine the Drive program and the possible construction of the Bears stadium. Jeannette Hoyt said tree oxygen production varies by tree size and that mature trees with more than 30 inches in diameter can produce over 240 pounds of oxygen a year.