Occupational health analyses the job and health relationships, in particular the chronic health influence of chemicals to workers. In most of the previous works for inherent hazards assessment, the focus was put on safety aspect; with very minor elements of health are taken into account. Most of the earlier design stage assessment methods focus only on the hazard identification and assessment part; but not the risk mitigation element. This study aims to create an assessment method that integrate the existing inherent hazards assessment index which is the Inherent Occupational Health Index (IOHI) with suitable Layers of Protection (LOP) strategies for each of the enlisted hazard parameters. The IOHI considers the health hazards existed during research and development stage. Risk prevention and minimization strategies are proposed according to each hazard parameters and levels. Scores are also assigned to each LOP strategies. Integration of occupational health hazard assessment index with the prevention strategy is achieved through a designed formula. The proposed method provides users with list of suitable counter measures for each hazard parameter, and each option offers varied level of effectiveness. The proposed index is applied to two process routes of methyl methacrylate production which are ethylene via propionaldehyde based route (C2/PA) and propylene based route (C3). The results revealed that the process routes are in the category of "safe" when the proposed control strategies are evaluated in the assessment. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.