Question: how to calculate number of negative air machines?
Answer: Divide 6, the industry standard for air changes per hour, by the number of air changes one machine would produce: 6 / 0.35 = 17 machines. Divide the number of machines by the building's area: 17 / 30,000 = 0.00056 machines per square foot, or 5 to 6 machines per 10,000 square feet.