What are the dangers of electrical transformer boxes?

not unless you pry your way into it with wet hands.

There is no danger. There are transformers all around us in every day of our lives.

looks pretty dangerous to me!

They are usually very safe.

But they can have bad days like anything else...

Transformer short circuit video MPEG

Transformer short circuit video RealMedia

building inspector
yes, and walking under a scaffold can get you hurt or killed by falling construction material. For all intents and purposes, it's relatively safe. If you have any question, and this pertains to real estate, hire a building inspector.

However, if what you're concerned about is the presence of electro-magnetic fields created by a high voltage device, then you can try measuring the field from inside the condo where you normal sit. Then compare those results with extensive research on the Internet on electromagnetic fields and human health. I recall the Swedish doing a research on presence of fields around high tension wires and human health. I believe the research was inconclusive.

Transformers convert very high voltage to usable voltage such as 550/3/60 or 110/1/60. I believe PCB is used in the transformers.