English 421K, Technical Writing

There is a lot of information that the intended audience does not need to know or it can be assumed they already know. In the first paragraph, the discussion about the policies is unnecessary and the history of incidents can be more concisely written. In the second, the intended audience, the employees, already know what they work with on a day-to-day basis. That whole paragraph could be summed up in a sentence: "Due to the dangerous nature of the chemicals we work with, we need a consistent safety policy that governs storage and handling of chemicals at all of our laboratories." The third paragraph is the most important, though there are still items the audience does not need to know. Such things as "at a meeting on November 1" can be struck.
Highlighting the purpose and main point of this memo would require putting the third paragraph first and rewriting the first and second as necessary to be support evidence for the actions called for in the third paragraph.
The action item in this memo is he calling of a mandatory meeting, and it should be at the beginning of the document.
To make the text easier to understand, the unneeded information can be cut out and paragraphs made smaller and more broken up.
To improve the readers' understanding, I would suggest highlighting the time and date of the meeting in some manner, like bolding the text. I would also highlight what needs to be done prior to this meeting because both of these items are lost in the middle of the last paragraph.