How a 1980s 'guerrilla science' test exposed London Underground's stale air crisis

A 'guerrilla science' experiment once tested oxygen levels on the London Underground to study the effects of poor air quality. The trial highlighted how stale air could lead to fatigue and low energy. It also showed the practical use of an early portable pulse oximeter in everyday settings. In the past, measuring blood oxygen required large, costly medical machines. This changed with the development of smaller, more affordable devices. An early portable model was used during a commute on the Underground, where oxygen saturation fell to 92% at its lowest point.

The device ran for nearly six hours and provided real-time readings. The experiment aimed to link poor ventilation and stale air to tiredness. Its findings contributed to the Underground’s decision to improve airflow in its deepest tunnels during the 1980s.

Today, modern pulse oximeters are compact, inexpensive, and widely available. Many also track heart rate and arterial blood flow. These advancements allow people to monitor their oxygen saturation at home with ease. Low oxygen levels, especially below 95%, can signal a serious health issue. Silent hypoxia, where symptoms are absent, became a major concern during the COVID-19 pandemic. Affordable monitoring devices now make it simpler to detect such risks early.