You might not want to read this one over lunch.

Researchers from the London School of Hygiene and Tropical Medicine report an alarming lack of hand washing in the UK. Taking swabs of commuters’ fingers in five major cities, they found bacterial signs of faecal contamination in a quarter of all subjects.

But then it gets bizarre. The further north samples were taken, the more poo bugs were present. In Newcastle, over half of all men had feculent fingers. Just 6% of their metrosexual counterparts in London, by contrast, had tainted talons. Women are reasonably constant in their cleanliness, with London again being the lowest.

Newcastle – men 53%, women 30%

Liverpool – men 36%, women 31%

Birmingham – men 21%, women 26%

Cardiff – men 15%, women 29%

Euston (London) – men 6%, women 21%

What’s going on here? Are people in the north really soap-dodgers? Some observations:

• Although the study was carried out by reputable scientists, it is only a preliminary report, and does not appear to have been peer reviewed nor published in a journal. So the figures may not be rigorous.

• The sample size is only 409, or roughly 46 men and 46 women in each city. Is this statistically significant?

• No mention is given in the reportage of the journey history of each participant. Local conditions in each city might predispose commuters to contamination to a greater or lesser degree than in another city. For example, someone who has caught two Metro trains and used four escalators in Newcastle before being swabbed will have been exposed to more potential contamination from fellow passengers than someone who’s just joined the bus queue in Cardiff. (However, by this argument, you’d expect London to be a bugfest.)

• Was the time of day kept constant between cities? If you swab during rush hour people are more likely to have clung to poles and straps than during off-peak times—surely a greater contaminant risk.

Still, it’s an interesting and stomach-turning piece of work. After yesterday’s atheistic bus adverts, it seems cleanliness is next to godliness in its absence from public transport.