Radon

Detective Inspector Charlie Resnick is the protagonist of a series of 11 police procedural novels by British writer John Harvey, based in the city of Nottingham.

Resnick is of Polish descent and loves sandwiches and jazz. The first novel in the series, Lonely Hearts was published in 1989, and was named by The Times as one of the "100 Greatest Crime Novels of the Century". 

There were two TV movies made about Resnick, based on Lonely Hearts and Rough Treatment, for the BBC in 1992 and 1993, starring Academy Award nominee Tom Wilkinson as the character. Screenplays for both were written by John Harvey himself. Several of the novels have been adapted for radio.

Radon is a colourless, odourless, and flavourless gas at ordinary temperature and pressure. Radon is radioactive and decays into other radioactive and toxic elements. 

It is always present outdoors and in drinking water from natural sources, but at a low level in open areas. It's mainly a problem in enclosed spaces, such as indoors or in a mine.