You aren't allowed to use mercury in schools because it is a poison.
1. Mercury is a poison
Inhaling its vapour can cause mercury poisoning.
Some of the symptoms of mild poisoning are:
- mood swings, irritability, nervousness
- weakness, muscle atrophy
High exposures can cause kidney damage, respiratory failure, and death.
2. Mercury spills are hard to clean up.
The main sources of mercury in schools are glass thermometers, mercury barometers, and bottles of mercury on the shelf.
Spilled mercury breaks up into tiny drops that can easily hide in tiny spaces like cracks in the floor.
The drops continue to turn into vapours that students and staff can breathe in for years afterward.
3. Cleaning up a mercury spill can be expensive.
It can cost up to $750,000 to clean up a spill.
In short, schools do not want to be sued for causing mercury poisoning in staff or students and they do not want to face the costs of cleaning up mercury spills.