"If you are losing faith in human nature, go out and watch a marathon," wrote Kathrine Switzer, the first woman to run the Boston Marathon. Covering a distance of 26.2 miles, marathons are the epitome of inspiration as runners of all shapes and sizes take to the streets to push their physical limits for causes that are near and dear to their hearts. And it turns out they bring more than just inspiration; they also bring clean air.

According to the nonprofit environmental group Global Action Plan, the city of London saw an 89 percent drop in air pollution on March 28, the day of the London Marathon. This data has many questioning what the city's air might look like without cars and just what methods could best improve London's air quality.

For their research, Global Action Plan evaluated data from a set of air quality monitors located throughout the city called the London Air Quality Network, which is managed by Kings College London. Researchers looked at air quality from 7 a.m. to 7 p.m. on the day of the marathon and compared that to the data from the three Sundays prior to the race.

The results were pretty remarkable. Air pollution in London dropped by 89 percent on the day of the marathon thanks to road closures that allowed participants to run in the streets.

How is it possible that one little race brought on such a huge improvement in air quality? As the speediest runners complete the race in as few as two hours, most mere mortals need twice or even four times that amount of time to tackle 26.2 miles on foot. Add to that the time it takes for set up and clean up and you can see why big city roads may be closed for an entire day to facilitate this kind of race. In London, Global Action Plan was able to use this information to get a better understanding of what the city's air might look like sans cars for a day.

"Taking collective action to tackle air pollution every day can make a massive difference, as shown at the London Marathon 2018," Global Action Plan Head of Health Larissa Lockwood told The Huffington Post UK.

As summer approaches and London and other large cities brace themselves for air quality issues, maybe the London Marathon can continue to inspire everyone to leave their cars at home and walk — if not 26.2 miles then maybe just a few blocks — to get where they need to go.

What London's air could look like without cars
This is what London's air would look like without cars.