This article examines the impact of implementing a certified management system under the ISO 45001 standard on workers' health and safety (WHS) in a region that has been little explored in this field. An empirical study was conducted on thirty medium-sized enterprises located in various regions of Algeria. Through a structured questionnaire addressed to different company managers, the overall results initially reveal a significant improvement in working conditions, risk prevention, and safety culture following certification. A comparative analysis of the results by industry sector, conducted subsequently, highlighted variations in impact depending on the sector, with particularly strong perceptions in the construction sector