Many of the rockets that launched from Baikonur were powered by UDMH (unsymmetrical dimethylhydrazine), a highly practical propellant for the forerunner Soviet scientists. UDMH didn't require an ignition source. It emitted a lot of energy and could be held at normal temperature. But the scientists who employed it eventually gave it the nickname "devil's venom".
Spaceflight is frequently portrayed in television and cinema as having little or no environmental impact. However, it should be evident that, like all combustion-driven propulsion systems, rocket engines release pollution into the environment.
Perhaps the emissions of black carbon, soot, and other substances were insignificant when only about 70 commercial rocket launches occurred each year. Given the rising demand for services like satellite internet services and space tourism, the number has already doubled and is projected to rise much more over the next 20 years.