Use 'stuffiness' to describe discomfort from poor air flow in indoor areas like rooms or vehicles. We opened the windows to alleviate the stuffiness in the car.
Pro Tip 2/3
Lack of Ventilation
'Stuffiness' often implies a need for fresh air or cooling systems in the environment described. Installing fans helped reduce the stuffiness in the overcrowded classroom.
Pro Tip 3/3
Heat Association
Although 'stuffiness' is not only about heat, it often accompanies a sense of warmth or humidity. The greenhouse suffered from stuffiness despite the cool weather outside.