Static electricity conditions — In which environment does static electricity most readily build up?

Introduction / Context:
ESD control is a cornerstone of electronics handling. Environmental factors such as temperature and humidity strongly affect charge buildup on people and objects. Recognizing risky conditions reduces device damage during service.

Given Data / Assumptions:

• General indoor service environment.
• No humidification systems in place.
• Standard clothing and flooring materials.

Concept / Approach:

Dry air allows static charges to accumulate rather than leak away. Cold weather correlates with low indoor humidity (heated air), so cold and dry conditions are notorious for strong static discharges—crackling sweaters, shocks from doorknobs, and ESD damage in labs.

Step-by-Step Solution:

Verification / Alternative check:

ESD program handbooks consistently show a drop in ESD incidents when RH is maintained above ~40%. Winter months typically show spikes in incidents when RH falls.

Why Other Options Are Wrong:

Humid conditions (warm/cold and humid) reduce static buildup. “Warm and dry” can be risky, but cold and dry is a more typical and severe scenario in electronics workspaces. “Cold and warm” is not a meaningful humidity descriptor.

Common Pitfalls:

Ignoring ESD precautions because a device “seems robust”; relying only on carpet sprays; not grounding the workbench or the technician properly.

Final Answer:

Cold and dry.