Occasionally articles or letters in newspapers here complain that things have changed for the worse or that the city are failing to clear certain bins or sweep certain streets but Copenhagen is remarkably clean and free from litter … and particularly for a busy city where many people actually live in the centre.

OK … sometimes bins in certain popular areas fail to cope with rubbish but on the whole, when you see rubbish on the ground around a bin in the street, then it's actually that the bin was fairly full and then birds, particularly gulls, have been after food waste, or foxes have scavenged and pulled things out in the early hours of the morning and, even in Copenhagen, they have not managed to train them to put the paper back when they have found and eaten the scraps of food.

You do see the odd person dropping the odd wrapper but it is remarkably rare.

But what I really, really don't understand is the number of fag ends everywhere and the round blobs of flattened chewing gum on the pavement but particularly near pedestrian crossings. Odd … do people really take the few seconds of waiting for the green man to appear as the best time to gob out their gum?

But I didn't realise this was all such a really huge problem until the Museum of Copenhagen reopened in their new building. Not, he adds quickly, that they are in any way responsible or guilty. Just that I stood and watched the full half-hour sequence of information about the city that flows past as an electronic version of ticker tape on their new data wall on the top floor.

According to the data wall, 80% of the rubbish cleared from the streets by city street cleaners is cigarette ends. That's 80% by weight. And remember they are plastic, or a certain sort of plastic, and now there must be health issues.

And the same with the gum … the problem with people spitting in the street is now rather more of a worry. Or don't people spit? I’ve never actually seen anyone at a pedestrian crossing spit but perhaps people are skilled and discreet and I've just not noticed. Do they rake out and drop? How does that fit with not putting your hands near your mouth now?

I'm not being holier than thou but I have never smoked and although I like the initial few seconds of the shot of peppermint from gum I hate that long chewing on a rubber band experience so go for mints … though I guess then that rots the tooth enamel but then the mints go down and not out onto the ground.

Unlike the fag butts, it's not the weight of the gum that is a problem but it gets on shoes and gets carried into buildings well at least when it's in the initial tacky stage - but then after it sets like concrete - or do I mean sets on concrete - then it costs the city, according to the data wall, 10 Danish kroner per blob to clean off the pavement.

Next time you walk along a Copenhagen pavement look at just how much it looks more like a dull mottled but blobby marble than like the granite or sandstone or limestone it is and think how much that will cost to remove.