A thorough and comprehensive understanding of real and potential hazards is best achieved by having a safety conscious attitude about everything you undertake in the field or lab. There are more insidious hazards that are often overlooked. These include O2 deficient areas like confined spaces and low areas. Oxygen can be displaced by other gasses or be consumed by chemical reaction and become suffocating. Excessive concentrations of O2 can be dangerous because of increased risk of combustion or explosion.
Confined spaces can contain pockets of trapped gasses.
Alley ways between buildings are often overlooked but may contain trapped fumes and stagnant gasses. Some electrical hazards may be obvious such as transformers, wires or electrical equipment. It may also include lightening or static charges generated by high powered electrical equipment. Underground electrical cables may be encountered during excavation. Stay dry and warm.