Ontario’s underground workers are being over-exposed to harmful diesel particulates, which cause occupational diseases. Ontario’s Occupational Exposure Limit for diesel particulates need to be reduced to 20 µm/m^3. The purpose of this study was two-fold: 1) to educate mine workers and community stakeholders about the hazards of Diesel Exhaust; and 2) stimulate policy-makers in Canada to take action to both enforce higher standards of protection and induce change in mine workplaces. We helped get the MLITSD to reduce the OEL from 400 µm/m^3 to 120 µm/m&3. Now our goal is to get the OEL reduced from 120 µm/m^3 to 20 µm/m^3. Relatedly, for her Masters work, Megan Wickie is evaluating the healthcare and economic burden of high diesel particulate matter occupational exposure limits in Northern Ontario’s underground mining industry.