According to revised mining safety regulations, the threshold limit for hydrogen sulfide is?

The correct threshold limit for hydrogen sulfide, as outlined in revised mining safety regulations, is 0.10% by volume. This limit is established to protect miners from the harmful effects of hydrogen sulfide gas, which can be toxic even at low concentrations. Exposure to hydrogen sulfide can lead to various health issues, including respiratory distress and neurological effects, making it crucial for mining operations to adhere to this safety regulation to ensure a safe working environment.

Regulations are often based on scientific research into the gas's toxicity and the necessary measures for the protection of workers. The chosen limit reflects a balance between allowing necessary operations and safeguarding health. It is essential for miners and safety personnel to monitor air quality consistently and implement ventilation systems to mitigate the presence of harmful gases like hydrogen sulfide.

In context, other options—such as 0.01%, 0.05%, and 0.15%—do not align with regulatory guidelines for safe exposure levels. Limits set too low could hinder operational efficiency without substantial benefit to safety, while a limit set too high would expose workers to unacceptable risks. Understanding these thresholds is vital for compliance and ensuring miners' health and safety in potentially hazardous environments.