Robert Angus Smith (1817-1884) was a 19th-century Scottish chemist who investigated numerous environmental issues.

Smith did innovative studies of air and water pollution and was one of the few at his time to realize the importance of finding solutions to the environmental problems caused by urban growth.  He is most famous for his 1852 research on air pollution, in the course of which he discovered acid rain.

Smith was appointed Queen Victoria's first inspector under the Alkali Acts Administration of 1863.  In the position, he became the model for the scientific civil servants of later generations.

Some of Smith's other areas of interests were public health, disinfection, and peat formation.  He also studied the chemistry of atmosphere precipitation, the results of which he published in his 1872 book, Air and Rain.  This work partly began the field that he titled "chemical climatology."

As a scientist, Smith was far ahead of his time both in his research and in the ideas behind it.