Industrial pollution prevention and control policies can achieve significant environmental, financial and human health gains. A growing number of countries use Best Available Techniques (BAT) to set industrial emission levels that are rooted in evidence and based on multi-stakeholder dialogue. Evaluating the effectiveness of BAT-based policies is essential to enhance their impact and strengthen future policy design. However, many countries lack the most appropriate datasets for an adequate effectiveness analysis of their BAT-based policies. This report provides an assessment of how governments can measure the effectiveness of their BAT-based policies to mitigate industrial pollution while generating benefits to society, such as improved air quality, and fostering efficient industrial operations. It presents the first comprehensive cross-country analysis of existing approaches to evaluating the impact of industrial emissions policies, and demonstrates the diverse approaches to such evaluations in the European Union, the United States, Chile, Israel, Korea, the Russian Federation, India, the People’s Republic of China, Kazakhstan and New Zealand. This is the third in a series of reports developed as part of the OECD’s BAT project.