ECJ EUROPEAN Cleaning Journal

Grabbing a handrail on the New York subway could transfer as many bacteria as shaking hands with 10,000 people, according to a new study.

Germs encountered on the Big Apple's underground system have been linked with respiratory problems and skin infections. And the study found New York's subway system to be by far the most bacteria-ridden out of five US city subway systems tested.

Logistics website Travelmath sent a team to gather bacteria samples from public transit systems in New York, Washington DC, Chicago, Boston and San Francisco. The study found that although most subway handrails harboured "surprisingly few" germs, New York was a major exception.

The team found around two million colony-forming units of bacteria per square inch on New York subway handrails which made them 900 times dirtier than the average aeroplane tray table.

At the other end of the spectrum was the Boston subway where a sample revealed only around 10 CFUs per square inch. The second most bacteria-ridden subway - San Francisco's Bay Area Rapid Transit - revealed a mere 483 CFU per square inch which puts New York in a league of its own.

Gram-negative rods - which can cause respiratory infections - and the types of yeast that can occasionally cause skin infections were among the contaminants to be found in the New York subway. However, scientists stressed that most of the bacteria discovered were harmless - and that some of them could even be beneficial for the immune system.