It depends on condition.
Generally eating too much/unhealthy or disease (even gingivitis tooth decay bacteria affect ulcer and heart etc too).
If you have very weak one, any sudden change like getting up, going up stairs, or physical activity that you are not used to.
Sometimes stress, emotion, fear, etc.
Drugs that increase heart rate.
Can create free radicals, H+ molecules.
No. In fact, being under a large tree could pose danger from lightning.
The skull and crossbones logo means poison.
Fortunately no-one died in the 2000 Eruption of Hekla. Hekla is in a remote location and has rather tame eruptions so it doesn't pose significant danger.
Brain stem.
Cheetahs pose some danger to livestock but little danger to humans. They are not known to attack humans.
sirens; theyre song pose the dangers
No
No, unless they pose a potential danger.
Crocodiles
No, they pose no danger to humans.
No they don't. They are not like lightning. They pose no danger to you.
Fennec foxes pose no danger to humans.
it is very dangerous to wildlife and can kill the animals.
because some protests can pose a danger to other citizens.
No. The storms on Jupiter do not affect Earth at all.
Vikings steal girls, goods, and polluted towns.