Spains Del Carmen Black Slate can be used for exterior applications in very dusty climates. However, it is important to note that regular maintenance and cleaning may be required to keep the slate free from dust and dirt buildup. Additionally, applying a sealer to the slate can help protect it from dust and other external elements. It is recommended to consult with a professional or supplier for specific guidance on the best practices for using Del Carmen Black Slate in dusty climates.