Toxins can enter your body via breathing, swallowing, or touching. The most common route is breathing. This is especially true for electricians, who tend to work around chemicals more than work directly with them.
But electrical work often involves using chemicals that can enter your lungs. These include fuel for portable generators, solvents for preparing connections, and paint for touching up enclosures. You may also be exposed to fumes from processes, batteries, or the activities of others.
Once fumes enter your lungs, they cross over along with life-giving oxygen to your blood. Then they may collect in your lymph system or travel to an organ such as your liver or your brain. Damage may not be immediately apparent.
Ventilation is a common way of reducing or eliminating exposure (e.g., ventilation hoods over fume-emitting processes). You can set up temporary ventilation, which may range from merely opening a door to using a fan. Identify the toxin in use, and read the MSDS for the ventilation requirements.