In January, a few days after the “Snowzilla” snowstorm hit D.C., schoolteacher Inez Steigerwald, 26, was biking to work down Michigan Avenue NE. Halfway to her destination, she hit a patch of slush.

“I lost control and went down straight on my elbow,” she says. “I totally shattered my elbow — two parts completely broke off — and had to get surgery to get it repaired.”

Steigerwald didn’t realize how dangerous bike riding was until she got hurt doing it. As it turns out, bikes are the most dangerous way to get around with the exception of motorcycles. That’s worth pondering as thousands of Metro commuters consider their alternatives during the coming “safety surge” of station closures and single tracking.

Nationwide, you’re more than twice as likely to die while riding a bike than riding in a car, per trip, according to a 2007 study led by Centers for Disease Control and Prevention epidemiologist Laurie Beck. Bike riding is also about 500 times more fatal than riding in a bus. Though Beck didn’t run numbers on subway and commuter rail systems, they may be the safest form of transportation of all. Despite a series of well-publicized accidents and maintenance issues, Metrorail and Metrobus reported just two injuries per million riders in 2015.

“With public transportation, you have the benefit of professional drivers, frequently traveling in urban settings at lower speeds,” Beck says.

In addition to accidents, cyclists face another major health risk: Air pollution. Bike commuters inhale about three times as much air pollution as drivers, according to a 2015 study conducted in Fort Collins, Colo. For that study, commuters wore backpacks that measured their exposure to different kinds of air pollution, including carbon monoxide and black carbon. The Colorado State University researchers found that cyclists, due to their heavier breathing and longer commute time, ended up huffing far more pollution than drivers.

It’s ironic that the people who are reducing emissions by not driving cars end up inhaling the byproducts of car combustion, says John Volckens, one of the study authors.

“We think bikers are choosing a healthier option, but it turns out bikers on long, crowded roads are getting exposed to air pollution,” he says. “Our study suggests that perhaps we should be doing more than putting lanes on roads. We should be separating bikes from cars.”

Given all these findings, cyclists begin to seem like selfless altruists, risking life and limb for the good of society. But while accidents and air pollution pose serious risks, bike commuting is still the best choice for your overall health, says Johanna Boogaard, a researcher at the Health Effects Institute, in Boston.

“Bikers do themselves a great benefit by getting active and healthy,” she says. “Exercise has not only huge cardiovascular benefits, it also helps against depression and other mood disorders.”

A 2010 study by Boogaard and her colleagues buoys that claim. While injuries rob casual cyclists, age 18 to 64, of five to nine days of life and air pollution subtracts between one and 40 days, the benefits of cycling adds three to 14 months to your lifespan.

Though she used numbers from the bike-friendly Netherlands, Boogaard says her study’s findings probably hold true for the U.S.

“There are more traffic accidents in the U.S., but because the calculated benefits are so large — think physical activity, especially important in inactive populations — it is unlikely that this would tip the balance,” she says.

In more good news for would-be bike commuters, it turns out that D.C. is relatively safe for cyclists, with only 1.5 bike fatalities per million residents, as compared to New York’s 2.4 and Philadelphia’s 1.9, according to 2014 data from the U.S. Department of Transportation.

That’s probably due to the city’s dedicated bike lanes and trails, Washington Area Bicyclist Association executive director Greg Billing says.

“We have some great bike lanes. Fifteenth Street is a national example, a win-win for everybody,” he says. “It has two protected bike lanes that, during rush hour, get around 400 bicyclists an hour.”

Of course, safety is just one thing people take into account when deciding how to get to work. Some people bike because it’s less expensive or better for the earth, or because they hate dealing with unpredictable Metro delays. For Steigerwald, biking is simply the fastest and most reliable way to get to work. That’s why, just six weeks after shattering her elbow, the first-grade teacher got back on her bike.

Steigerwald says she’s always been a safe biker, but now she’s being extra cautious.

“Since my accident, on days when it’s been raining, I’ve been taking the bus or Car-to-Go, because I don’t want to risk getting injured again,” she says.

What cities are most dangerous for cyclists?

Fatalities per million residents in 2014.

1. Tucson, Ariz. 11.4
2. Phoenix 7.2
3. Denver 4.5
4. Detroit 4.4
5. Columbus 3.6
6. Oklahoma City 3.2
7. Seattle 3.0
8. Houston 2.7
9. New York City 2.4
10. San Francisco 2.3
11. Chicago 2.2
12. San Diego 2.2
13. San Jose, Calif. 2.0
14. Philadelphia 1.9
15. Fresno, Calif. 1.9
16. Los Angeles 1.8
17. Albuquerque, N.M. 1.8
18. Baltimore 1.6
19. Washington, D.C. 1.5
20. Boston 1.5

Source: U.S. Department of Transportation