Mind The Germs

mind the germs: mapping bacteria in the London underground

Overcrowded stations. Rubbish left on the train. Fellow passengers who shove, wear enormous rucksacks, or snack on pungent foods while they ride. There’s no denying the journey through the bowels of London can be fraught with challenges, whether you’re a daily commuter or an infrequent traveller. But there’s a different Tube travel bugbear that many people overlook altogether: the germs.

More than 1.34 billion passengers ride the Tube every year. Just picture all those hands touching escalator handrails, ticket machines, barriers, seats, and poles – it’s a veritable recipe for germ stew. To determine just how bacteria-laden various surfaces are in the London Underground, we sent a team to swab 60 surfaces total along the 10 busiest lines and then had the samples tested at an independent laboratory. Come along as we take a germ-focused journey throughout the grimy underground jungle.

Where do Bacteria Lurk?

mapping germs in the tube

Generally speaking, a map of the Tube is quite easily recognisable. However, the map above is quite different from any other you have seen before; it tracks the bacteria levels of various lines and stations. These bacteria levels are measured by counting the colony-forming units (CFU) – which refers to the number of viable bacteria cells – that thrive in every 10 centimetres

Not only is the Northern Line home to the longest tunnel and the deepest station, but it also hosted by far the most bacteria on average – more than 1,600 CFU/10 sq cm. Based on the samples we took, the Northern Line was nearly three times germier than Central, almost 15 times more bacteria-laden than Waterloo & City, and a shocking 91.5 times more germ-ridden than Hammersmith & City. In our samples,the Central Line was also relatively bacteria-ridden, while Bakerloo and Waterloo & City had fewer germs. Conversely, the Hammersmith & City Line samples contained scant bacteria: only 18 CFU/10 sq cm.

Germs By Station

mapping germs in the tube

Tube stations are busier and more crowded than ever. But the busiest stations (based on official exit and entry figures) were not necessarily home to the most bacteria. Among every station, Stratford (only the seventh-busiest station) contained the highest bacteria levels. The second-germiest was Bank & Monument (the eighth-busiest), and Victoria (the fourth-busiest) had the third-highest germ levels. Canary Wharf (the ninth-busiest station) averaged the fewest germs, followed by Liverpool Street (the fifth-busiest) and London Bridge (the sixth-busiest).

Favourite Spots for Germs to Converge

most germ-ridden surfaces in the london underground

Virtually every Tube station has a characteristic that sets it apart, be that good or bad: Some are known for futuristic architecture, while others are notorious for their crime levels. Based on our bacteria tests, it turns out the stations we studied are also unique in that they had varying bacteria levels in different spots.

Planning a stop at Bank & Monument? Don’t let your hand linger on the germ-ridden escalator handrail. Beware of both the ticket barrier and the touch-screen ticket machine at Stratford Station. And while you’re riding the train, you’ll want to avoid hanging on to the vertical poles on the Northern Line (the germiest surface of any we tested). Also, watch out for the seats on the Central Line and steer clear of grasping the ceiling poles on the Waterloo & City Line.

The Germiest Spots Stacked Up

how do the tube's dirtiest surfaces compare

Without a basis for comparison, it might be difficult to envision just how many bacteria thrive on various surfaces along each line and at each station. Matching them up with surfaces in the average loo yields some striking results: With one minor exception, based on our tests, all types of surfaces (handrails, ticket machines, ticket barriers, seats, vertical poles, and ceiling poles) harbour several times more bacteria than toilet seats, toilet handles, and washroom light switches.

Tube travellers frequently complain about fellow passengers who cough and sneeze indiscriminately in such close quarters. And given the recent study that revealed 6 in 10 men and 4 in 10 women fail to wash their hands after using the toilet, it seems only natural that these surfaces are laden with bacteria after contact with millions of hands.

Busiest Stops for Bacteria

most germ-ridden stations

If only the London Underground voice announcements said what you may be thinking the next time you approach Stratford: “The next station is Germ Central.” Indeed, our tests reveal that Stratford Station teemed with 1,220 CFU/10 sq cm – more than twice as many germs as any other stop. Bank & Monument and Victoria were neck and neck for second-germiest station honours, with just over 500 CFU/10 sq cm. On the other end of the bacteria spectrum, Canary Wharf, Liverpool Street, and London Bridge all averaged fewer than 100 CFU/10 sq cm.

The Lines Where Bacteria Commute

most germ-ridden lines

Based on our tests, the germiest line by many miles was Northern, which teemed with nearly 1,700 CFU/10 sq cm. Central, too, had a disturbingly high bacteria level of 597 CFU/10 sq cm. Bakerloo (117 CFU/10 sq cm) and Waterloo & City (110) also had germ counts of over 100 CFU/10 sq cm

Not all lines showed such high levels of bacteria. The Docklands Light Railway (DLR) had only 90 CFU/10 sq cm, while the Victoria line had 87. The Jubilee and Hammersmith & City lines were at the bottom with only 52 and 18 CFU/10 sq cm, respectively. This represents an extraordinary range of bacterial concentrations, with the most and least germ-ridden lines differing by a factor of more than 90.

Germs On The Handrails

dirtiest escalator handrails in the tube

It’s second nature to steady yourself with the handrail while riding an escalator - and it’s something that the Tube recommends for your safety to prevent dangerous slips and falls. Yet even lightly trailing your hand along the rail at one station could mean coming in contact with a surprising quantity of bacteria. Based on our tests, the escalator handrails at Bank & Monument averaged a shocking 800 CFU/10 sq cm. This level of bacteria was 10 times that of Oxford Circus and 20 times that of Liverpool Street, Stratford, and Victoria.

One study of escalator handrails at American malls revealed truly terrifying results: The surfaces contained urine, mucus, faecal matter, and even blood. Researchers noted the handrails also hosted respiratory flora, which can cause viruses such as cold and flu because people tend to cover their mouths when they cough.

Bacteria On The Monitors

dirtiest touch screen ticket machines in the tube

Compared with days of yore, today’s Tube ticketing process is positively civilised. But at some stations, our tests revealed that the touch-screen where you make your payment teemed with bacteria – 560 CFU/10 sq cm on average. Stratford was home to the germiest screens, which contained more than 2,500 CFU/10 sq cm. Victoria and King’s Cross St. Pancras also had fairly germ-laden monitors.

Touch-screens are notorious for harbouring germs. Even worse, these screens also allow for easier transfer of bacteria compared with other surfaces, according to researchers from the London School of Hygiene & Tropical Medicine and Queen Mary, University of London.

And once germs hit people’s fingertips, researchers say, it’s a relatively short trip to their eyes, nose, and mouth – after all, consider how many people chew their fingernails out of habit. It seems that someday the Tube may be well served by introducing groundbreaking antibacterial touch-screens.

Germs On The Ticket Barriers

dirtiest ticket barriers in the tube

For anyone new to Tube travel, negotiating the ticket barriers can prove somewhat challenging. But even if it’s old hat, you may not have realised just what you were getting yourself into. Though our tests showed that the barriers averaged 326 CFU/10 sq cm, a few teemed with far more germs than that.

At Stratford, you might encounter more than 1,000 CFU/10 sq cm as you make your way through. Those barriers hosted more than twice as many as the next-germiest spots: Victoria, Oxford Circus, King’s Cross St. Pancras, and Bank & Monument. The barriers at Canary Wharf – where a turnstile once gained fame when it began to emit an unusual musical noise – contained relatively few germs.

Germy Places On The Tube

dirtiest car surfaces in the tube

If you ride the Tube frequently, you’ve probably already mastered the etiquette involved: Remove enormous rucksacks, don’t hog the poles, and give up your seat to mothers with babies, women who are expecting, and elderly passengers. However, considering the germs we encountered, avoiding poles and seats may become a priority rather than a polite obligation.

According to our tests, the germiest surfaces by far were the vertical poles on the Northern Line, which teemed with 4,720 CFU/10 sq cm. The Central had the most bacteria-ridden seats, covered in 1,720 CFU/10 sq cm. The ceiling poles were the cleanest surfaces, most likely because they are touched less frequently than other surfaces. These may be your best bet for steadying yourself and steering clear of germs.

Bacteria On Tube Surfaces

most germ-ridden surfaces in the tube

By averaging the bacteria levels, we were able to rank every surface we sampled based on the number of germs present. The touch-screen ticket machines were the most germ-laden surfaces, containing 560 CFU/10 sq cm on average. The vertical poles harboured 518 CFU/10 sq cm, the ticket barriers 326 CFU/10 sq cm, and the seats 273 CFU/10 sq cm. You can worry less about the escalator handrails, and the infrequently touched ceiling poles were the cleanest of all the surfaces.

Staying Healthy Amidst The Germs

The number of passenger journeys on the Tube has risen by one-third in the past 15 years, and the transportation system just keeps getting busier. Although they’re not visible to the naked eye, thousands of bacteria are along for the ride. Not all types of bacteria are harmful to humans. However, our analysis had some interesting results, revealing that certain spots on certain lines seemed to be absolutely writhing with bacteria. While scientific findings on health risks from public transportation aren’t conclusive, With all these germs around, if you’re not careful, you could be at risk of catching anything from a cough to a gastrointestinal illness.

The NHS recommends making hygiene a daily practice both at home and when out and about, as many bacteria and viruses can survive on surfaces for several hours. The most important step any traveller can take is frequently handwashing with soap and warm water. This is the most effective way to curtail the spread of infections. Carrying some alcohol hand gel to use after your journey can also help prevent the spread of some infections. During your Tube journey, try to avoid absentmindedly touching your hands to your face, cover your mouth and nose with a tissue if you cough or sneeze, save your snacks and meals for after the journey, and wash up as soon as possible once you arrive at your final destination.

According to NHS Choices, you can help curtail the spread of illness through other simple steps, including avoiding unnecessary contact (including Tube travel) if you’re ill and getting an annual flu jab if you’re at risk. You can also reduce the spread of germs at home by removing your shoes before you enter and cleaning clothing and handbags that may have picked up bacteria.

At Zava, we care about your health, and our comprehensive doctor service offers a range of health solutions. Perhaps you need treatment for a chronic condition such as high blood pressure. Maybe you want to improve your overall well-being through weight loss or smoking cessation. Or you might wish to ensure you stay healthy on an upcoming trip by securing treatment for traveller’s diarrhoea or tablets to prevent malaria. Whatever your needs, you require no appointment, and your treatment is delivered quickly and discreetly. Visit Zava for more details.


Envirocheck (U.K.) Limited provided analysis for 60 bacteria swabs. We chose the 10 busiest stations in the London Underground based on the TFL’s 2016 annual entry and exit figures. Our team’s ride to the 10 different stations took them on eight different lines. The bacterial numbers presented are the total viable count (TVC) measured in CFU/10cm2 for 48 hours at 30ºC. No coliforms or E. coli were detected.

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