We operate a gas-fired power station. A colleague has raised the possibility that radon in the natural gas could contaminate the filter cartridges used in gas scrubbing. Is this true, and if so, would the levels be high enough to constitute a hazard to our staff? Also, would the cartridges qualify as radioactive or hazardous waste when we dispose of them? The radon levels in the gas we use are listed as 2–80 Bq/m3 at the source — this is prior to scrubbing.