Toronto Transit System (TTC) seats

What Are the Dirtiest Surfaces on your TTC Commute?

An average of 1.5 million people ride the Toronto transit system (TTC) every single day1. With this much traffic it’s no surprise that subways and buses are a breeding ground for bacteria. As flu season kicks into high gear, we asked ourselves “What is the dirtiest part of people’s daily subway commute?”. So our team ventured down into the TTC with an ATP test meter and some swabs in hand.

What is "ATP"?

For non-microbiologists in the crowd: ATP testing is a technology used to quickly analyze the amount of bio-load on a surface. This type of testing is regularly used in food processing and healthcare facilities to assess the cleanliness of the environment (more on that here2).

While ATP won’t tell you what kind of microorganisms are present – this requires long and costly testing – it will tell you how many organic items are on that surface. Results are measured in “Relative Light Units” (RLUs), which tell us the concentration of bioload from a surface or swab. RLU scales are different for each manufacturer. Here is how the manufacturer of our ATP meter breaks it down:


Figure: ATP meter levels of clean

TTC Swab Results

We swabbed common rider “grab” locations in four different subway trains travelling from St George to Union stations, and the kiosks at two downtown stations. Here are the results:

Loser: The red rubber on the subway pole is by far the dirtiest part of the TTC commute, with an average of 1467 RLUs per swab. 

Winner:  The solid round “pull down handle” was most hygienic surface in our tests, averaging ⅓ of the bacteria of the rubber poles.

The metal-only poles and the upper-metal parts of the subway poles were also dirty, but not as cringe-worthy as the main subway poles.

Lastly, we swabbed the smartphones of several riders as they exited at St. Patrick and Queen’s Park stations. They turned out to be the second-dirtiest surface we swabbed, and one rider’s cell phone had over 2300 RLUs.

How to Protect Yourself

None of this means you should avoid public transit or risk falling by not grabbing the subway handles. This bacteria is often harmless but it can include bacteria like staphylococcus aureus,  E. Coli – which, yes, often comes from poop – and viruses like influenza. For people with weakened immune systems or those in the hospital, exposure to these bacteria can be life threatening.

There are several ways you can reduce cross-contamination risks on the TTC, especially during the flu season:

1. Wear gloves on the subway. This stops the bacteria from directly touching your skin. However, keep in mind that the microorganisms will survive on your gloves without regular cleaning.

2. Wash or sanitize your hands after leaving the subway. Especially before touching your face or eating food.

3. Use Presto’s auto refill function online to avoid touching the kiosk screens!

4. Sanitize your mobile device. If you use your phone in the subway you are transferring bacteria directly onto a warm, portable germ-carrier. Try and clear your screen of these germs – especially if you are going into hospital or food facilities where bacterial contamination is a bigger concern. In the GTA, Mackenzie Health3 provides a visitor-facing UV solution to address this issue.

Where We Swabbed

We chose St. Patrick and Queen’s Park stations because they lead into downtown Toronto’s healthcare core where Sick Kids, Mount Sinai and Toronto General hospitals are located. The TTC is a common transportation option for hospital staff and visitors, and cross-contamination from public transit into these environments (or vice versa) is an increasing concern.

As a company dedicated to easily and quickly eliminating bacteria on mobile devices, we’re always interested in learning how people’s routines can impact bacterial risks and best practices in facilities.

With only 56 swab samples this wasn’t a thoroughly scientific study. Yet, studies done by our academic partners and hospital clients often show just how big of a challenge hand hygiene, mobile device sanitization and infection control more broadly can be. The best practices listed above can help address these concerns.

So whether you’re commuting to work, headed to dinner with friends, or going into hospital, we hope you keep in mind how dirty these common surfaces can be and take some quick steps to protect yourself and others.

Interested in learning how we enable hospitals to solve the challenges associated with bacteria on visitor & staff devices? Visit


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