To modify the requirements of Sentence 2.2.3.1.(1) [specifically Clause 2.2.3.1.(1)(a)], which would otherwise permit a lesser depth, on the basis that a greater minimum trap seal depth will provide additional protection where exposure to acid gases is possible in an acid waste system. This [greater seal depth] is to limit the probability that inertia of the water flow [pressure differential] and evaporation, or malfunction of mechanical devices, will lead to the failure of trap seals, which could lead to the leakage of sewer gases into the building, which could lead to a negative effect on indoor air quality, which could lead to harm to persons.