What safety measure should be taken when working with man hole covers?

When working with manhole covers, checking for stability before opening is crucial for safety. Manhole covers can be heavy and may be dislodged by various forces, including traffic, weather, or nearby activities. Ensuring stability helps to prevent accidents, such as the cover slipping or falling, which could lead to injury. It is also essential to assess if the area around the manhole is safe, as unexpected hazards could arise from surrounding conditions.

In contrast, while wearing gloves, ensuring proper ventilation, and working only during the day are all important safety practices in certain contexts, they do not address the immediate concerns posed by the instability of manhole covers specifically. Gloves primarily protect hands from cuts and abrasions, ventilation is crucial in confined spaces where fumes may accumulate, and daytime work can increase visibility and safety but does not inherently ensure stability or safety when opening a manhole cover. Therefore, checking for stability is the most pertinent safety measure in this case.