Bad Air

The general, everyday term British miners used for any unbreathable underground atmosphere — oxygen-deficient, suffocating air, as opposed to the explosive firedamp — used across metal and coal mining alike, long before, and alongside, the more specific 'damp' terminology coal miners developed.

Historical usage

'Bad air' (also called stythe in parts of North East England) is an older, more general term than blackdamp or chokedamp, used wherever miners worked — not just in coal — to describe air too depleted of oxygen to breathe safely. It built up naturally in old, poorly ventilated workings, dead-end drives and disused shafts, where decomposition and the miners' own candles or lamps steadily consumed what oxygen was present with nothing to replace it.

How it worked

Because bad air is invisible, odourless and gives no warning to the body until a miner is already dangerously short of oxygen, its presence had to be judged indirectly. The standard test for centuries was a simple candle or lamp flame: as oxygen levels fell, a flame burned lower and more feebly before finally going out altogether, well before the air became lethal to a person — giving a working, if crude, early warning system long before any instrument existed to measure gas levels directly.

Why it was used

Recognising bad air as a distinct hazard from firedamp mattered because the two called for opposite responses: firedamp demanded avoiding any flame or spark, while bad air was best detected using one. Any mine without active ventilation — natural airflow through connected shafts and adits, later assisted by underground furnaces and, eventually, powered fans — was at constant risk of it, making ventilation one of the oldest and most basic mine safety disciplines, predating any of the named toxic gases by centuries.

Risks & limitations

The candle test was useless against firedamp, which it could ignite outright, so miners had to judge from context — a stale, dead-end working was tested for bad air with a flame; a gassy coal seam was approached instead with a safety lamp built to contain any flame entirely.

Disasters associated with this term

Included only where MineArchive's own research gives a reasonable evidential basis, with the nature of the relationship stated — not every disaster where this term might plausibly apply.

• Magpie Mine suffocation of three Maypitt miners (hazard involved)
  The three men died from suffocation in an atmosphere made irrespirable by deliberately lit smoke, the same underlying hazard as bad air more generally.

Sources

1. (primary) P11-18 — Mine Safety and Health Administration (MSHA)
2. (secondary) Blackdamp — Wikipedia
3. (secondary) Mine Tales: From candles to canaries, ventilation is a vexing challenge — Arizona Daily Star

Record created: 20 August 2026 · Last researched: 20 August 2026