Which factor is least important in reducing sewage gas?

Earthworms play a role in the decomposition of organic matter in soil, but they are not directly involved in reducing sewage gas in a sewage management context. Proper ventilation systems are crucial as they help dissipate harmful gases directly, promoting air circulation and reducing gas buildup. Frequency of waste removal is essential to prevent the accumulation of waste that can emit gases. Similarly, sewage treatment processes are designed specifically to manage waste and minimize odor and other gaseous emissions by breaking down contaminants effectively. While earthworms contribute positively to soil health, they do not address the immediate concerns related to the management of sewage gas, thus making them the least important factor among the options provided.