Most parents will have long suspected the ball pit at the local soft play centre of being a fetid swamp of disease and destruction, and now, according to a not entirely scientific study, it turns out 99.9% of play areas, ball pits and toys in shared public spaces are “a hive of germs”. The claim was made by Mark Hall, the managing director of StemProtect, a stem-cell-bank company, who took an interest in the dirtiness of shared play spaces as a father of two small children.

He surveyed the managers of 60 pubs, alongside 600 parents, who told him stories of children exposed to vomit or faeces, and one who said that, after their child had urinated in a ball pit, they left without reporting it because they were too embarrassed. Hall did not do any lab testing of any plastic balls from play areas. “You don’t really need to do a test. You can see the dirt and grime on these things.” He came up with the 99.9% figure, “from looking around and speaking to people and asking them about the cleanliness, and speaking to people who knew about bacteria”.

Should we be alarmed? Ball pits, says Sally Bloomfield, honorary professor at the London School of Hygiene and Tropical Medicine, “will become contaminated in the same way as any environment where there are a large number of children will become contaminated. What worries me is what people mean by the word ‘germs’. I’m so fed up of reading reports saying there are millions of germs, when they’re talking about harmless bacteria.”

Also, she points out, organisms of faecal origin might not sound pleasant but are not necessarily harmful in themselves. However, their presence does indicate poor hygiene standards, “which means that if there is an infected child [who has had, for example, norovirus] using the play area, there is significant risk that the balls would be contaminated. The harmful microbes can survive for quite long periods, so regular cleaning is important to reduce risks.” A visibly dirty ball pit “means that they are not being routinely cleaned. There is a need to ensure that these play areas are properly managed, in the same way that a public swimming pool needs to be.”

It’s impossible to eliminate risks of infection, but you can minimise risks, says Bloomfield, while not being paranoid. “Children should always be expected to wash their hands before they handle and eat food, [and] after they’ve been to the toilet.” And, perhaps, after playing in ball pits.