An employer and the union jointly agreed to a new work shirt to be worn by workers in the smelter. But the employer also unilaterally imposed a new safety rule requiring this shirt to be tucked into a worker’s pants. The union opposed this rule. The arbitrator noted that the employer required workers to tuck in their shirts at other locations. The safety reasons for the tucking rule include reducing workers’ risk of exposure to air contaminants, protecting workers from splashes of molten metal, reducing the risk of the shirt’s entanglement in equipment and reducing the potential harm from electric spark flashes. Workers who don’t want to tuck can wear coveralls. Management has both the right and obligation to ensure that its OHS standards comply with the law, said the arbitrator. And the OHS laws support the new shirt tucking rule. So the arbitrator dismissed the grievance [Rio Tinto Alcan Inc. v. Unifor, Local 2301 (Change to Personal Protective Equipment Standards Grievance),  B.C.C.A.A.A. No. 52, June 3, 2016].