Question

Clean air should contain less than __________ of suspended impurity per cubic metre.

(a) 0.5 mg

(b) 1.5 mg

(c) 2.5 mg

(d) 3.5 mg

I got this question in homework.

I'd like to ask this question from Functional Requirements of Ventilation System in section Acoustics and Ventilation of Construction & Building Materials

Answer 1

The correct answer is (a) 0.5 mg

To explain I would say: Clean air should contain less than 0.5 mg of suspended impurity per cubic metre. Also, it should have less than 0.5 part per million of SO₂. Air should be free from toxic fumes of gases and harmful particles.