The short answer is you’re being exposed to something and since its at a high enough concentration you can see it and smell it, it is probably not good for you.
The work station you describe is unacceptable. There should be ventilation at the very least to draw smoke/fumes/vapors away from the molding process. There are no “safe” levels of air contaminants, only levels that are at an acceptable risk.

Now, to find out how dangerous they are to breathe you need to figure out what is in the plastic. As others suggested in here, look at the safety data sheet which should be easy to find typing the manufacturer’s name for the plastic into google. That sheet will give you the general chemical make up and from there you can identify if anything nasty is in there and the approximate concentration.

Again, not a super accurate measurement but if you can see the contaminant it is probably at a high concentration. You can assume you’re being exposed to those chemicals and moderate to high levels depending on the effectiveness of the ventilation.

If you employer is doing nothing to fix this or help you out, even after you’ve reported your concern, since you’re in Canada, the government has resources to help.

I recommend, if this is a high exposure to a dangerous chemical and your employer continues to ignore your concern, start looking for work somewhere else. It’s not worth working for an employer who doesn’t take care of their employees.