Background and purpose: People are exposed to various chemicals during life especially in their working environment. Some of these chemicals have potential health risks. In risk assessment of chemicals, necessary actions are recommended to protect the involved people against hazardous chemicals. This study was designed to assess the semi quantities risk of TDI and MDI in car paint shops in Alborz province, Iran.

Materials and methods: A cross-sectional study was performed in 2013. Singapore's Workplace Safety and Health framework was used for risk assessment of TDI and MDI in car paint shops. The samples were collected from car paint shops using NIOSH 5522 method and analyzed by HPLC.

Results: Hazardous rate of TDI and MDI were 2 and 3 and the exposure rate of materials was 5. Risk factor of TDI and MDI were 3.8 and 3.1. Risk ratings for TDI and MDI were high and average, respectively.

Conclusion: In risk assessment the Singapore's Workplace Safety and Health framework is used for prioritizing control actions. The main drawbacks of this method are lack of risk evaluation (determining acceptable or unacceptable risks) and not considering the effect of high concentrations in measuring the exposure rate.