A worker's hard hat must protect from which of the following?

The requirement for a worker’s hard hat primarily focuses on protection against impacts and potential injuries from falling or flying objects. A hard hat is designed to shield the head from direct blows as well as any side impacts that may occur due to various activities in the work environment. The need for this type of protection is emphasized in workplace safety standards, particularly in environments where there is a risk of heavy objects falling or being struck from the side, such as construction sites or industrial facilities.

While other factors like wind and rain, sparks and flying debris, and extreme temperatures are pertinent in different contexts of worker safety, the pivotal function of a hard hat is its structural integrity and ability to withstand forces that could result in head injuries. The design of hard hats specifically incorporates features to absorb and distribute shock from impacts, making it essential for defending against both direct blows and lateral strikes commonly encountered in hazardous work zones.