It’s frankly impressive just how many different ways there are to get cancer from dungeon-crawling. Today’s carcinogen: radon, nature’s answer to cigarette smoke.

It’s frankly impressive just how many different ways there are to get cancer from dungeon-crawling. Today’s carcinogen: radon, nature’s answer to cigarette smoke.

Radon is a naturally-occurring element which exists as a gas at pretty much any temperature you’d find on Earth. It’s colourless, tasteless, odourless, and basically totally imperceptible without special equipment. It’s one of the “noble” gases, meaning that it’s fairly stable and doesn’t tend to react with other chemicals. Radon is naturally radioactive, which can make it harmful to humans with prolonged exposure, but what really makes radon potentially dangerous is the dust that it produces as it ages and decays. Whereas a person might breathe radon in and out, radon decay dust can stick to the inside of the body, causing irritation and increasing risk of cancers. Between the effects of the two forms, radon is thought to be the second biggest cause of lung cancer in the world, which means that in a medieval fantasy setting where tobacco products aren’t widely available it may be number one.

While radon is found in low concentrations everywhere, what makes it interesting for us is where it’s found in highest concentrations: underground. Radon is produced as certain forms of stone decay, which means that it has a tendency to accumulate and pool in tunnels and caves, where there’s not only lots of stone but also very little airflow to disperse it. It can seep into buildings through cracks in foundations, or mixed with water or natural gas that gets piped in, but in a game setting, and especially campaign settings which predate poured concrete and indoor plumbing, radon is mostly a danger to people who spend a lot of time in tunnels. Long before radon was known to exist, Renaissance-era miners were known to suffer from various wasting diseases with names such as mala metallorum and mountain sickness. It’s hard to know for certain if this was due to radon, as miners are at risk for a whole host of dust-related lung diseases such as pneumoconiosis, but it’s very likely that uncountable deaths throughout history have been due to radon- and radon-dust-induced cancers. In a fantasy setting, miners aren’t the only people who spend a lot of time underground. Dwarves, drow, denizens of the Underdark, and of course, adventurers probably all suffer disproportionately high rates of sickness and death. Given that it takes a few years for lung cancers to develop, most adventurers will at some point be subjected to disease-removing magic which will eliminate a cancer before it ever has time to have a health impact, but some will inevitably develop the occasional point of otherwise unexplained Constitution drain. Whether this gets attributed to environmental hazards or invisible ghosts will depend very much on the educations and outlooks of the characters involved.

Medieval scholars probably have no idea that radon exists, as it was only discovered in our history at the close of the 19^th century, when specialized labs began seriously investigating radioactivity, and it wasn’t identified as a meaningful health risk until the 1970’s and 80’s. Alchemists or researchers in a fantasy setting who know of radiation, or who use magical means to discover otherwise undetectable substances in their environment, might know about radon. Given the things that pseudomagical alchemy is capable of, a fantasy setting might have some form of radon detection in mines to protect workers, or might have even weaponized it as a form of ultra-slow acting poison to use against enemies. More likely, though, radon is a silent killer totally unknown to mortals, who effects are chalked up to other toxins, misfortune, natural causes, or curses. 

More than four years ago, Dr. Eris Lis, M.D., began writing a series of brilliant and informative posts on RPGs through the eyes of a medical professional, and this is the one that appeared here on September 12, 2015. Lis is a physician, gamer, and author of the Skirmisher Publishing LLC OGL sourcebook Insults & Injuries, which is also available for the Pathfinder RPG system.