The whole broken windows philosophy is not a new one and has gained worldwide acclaim since the likes of Malcom Gladwell featured it heavily in their work.  It suggests that by making the small things right you can often tackle the bigger things.  So the by fixing the broken windows in the name you make the neighbourhood appear more respectable and thus reduce instances of more serious crime.

That kind of thinking, together with other behavioural economics insight has infused public policy in recent years.  The British government for instance have a 'nudge' unit to persuade us to do the right thing.  The amount of litter on public transport could be one such project, and new research suggests that the key to having clean public transport is to ensure your carriages smell right.

The research from a team of Dutch social psychologists suggest that a citrus smell similar to that found in cleaning products is enough to encourage people to either keep hold of their rubbish or put it in the bins.  They tested their theory by placing scented containers in the luggage rack of two carriages, whilst another two were left scent free.  They collected the rubbish dropped at the end of the 1 hour 45 minute journey for comparison and totted up the average over 18 seperate journeys.

The results are quite amazing.  The unscented carriages had three times as much rubbish dropped as the scented carriages.  To ensure that these results weren't simply a bad day, they also collected rubbish on the same train on the same route over several journeys a week earlier to gain a base level to compare against.  On these journeys the litter dropped was consistent with that in the unscented train during the experiment.

"It seems to be possible to change the littering behaviour of people in a train environment using a simple and relatively cheap intervention," the researchers said.

The research suggest that we drop less litter when we smell things that unconciously remind us of cleaning.  Other experiments for instance have used the same kind of smell to encourage people to clean more often and leave fewer crumbs when they eat.

"The positive results of our scent manipulation in a field setting provide support for the idea that the cognitive route of scents to behaviour can be used as a tool for behavioural change," they said. "Merely dispersing a scent seems to trigger related goals and influence subsequent behaviour."

Of course having a pleasant whiff wafting through the carriage might help combat some of the dubious odours eminating from our fellow commuters, which on a cramped train with summer fast approaching would be no bad thing.