Drink, drugs and disease: the chemistry of breath tests

An image showing a driver using a breathalizer

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From roadside tests to diagnosing Covid-19, Clare Sansom looks at how breathalysers have developed

Smelling a person’s breath was one of the first diagnostic tests known, even as far back as Roman times. The sweetish smell of acetone on a person’s breath was a strong indication that they were suffering from diabetes mellitus. Breath analysis technology has advanced dramatically since then, of course, but the technology that people are most familiar with is a forensic one: the roadside breath test for alcohol.

Many people will have seen the occasional driver being asked to blow into a hand-held device to test their sobriety. Similar tests for driving under the influence of drugs are beginning to be developed and comparable techniques are now used in diagnosing lung conditions including Covid-19. The hope is that, after the pandemic passes, techniques developed for diagnosing this viral infection will find other applications in respiratory medicine and beyond.