Why do we have to do chemical equations and calculations?

(A look at workplace exposure limits found in MSDS sheets)

There is useful information in section 8 of a (Material) Safety Data Sheet (MSDS) that teachers can use and shows how a knowledge of chemical equations and calculations helps protect the health of their students and themselves and helps to assure their employers and safety officers that teachers and lecturers are responsible and professional users of chemicals. 

Is the MSDS Sheet a useful document for a chemistry teacher?

Whenever a serious incident takes place in a school chemistry laboratory or classroom, fire and safety officers often pontificate on the incident by quoting the Materials Safety Data Sheet (MSDS). However, how many of you have read such documents in full? In UK schools we have perhaps 200 to 400 chemicals on the shelves. Have you read the MSDSs for each chemical?