Even eco-types like us can be couch potatoes (though the couch is formaldehyde-free and our potatoes are organic and locally grown). But when the clock says 5:03 p.m. and the stress of your last meeting lingers on, nothing beats the satisfaction of a sweat-inducing, tension-releasing workout. (Well, that or a good stiff bourbon.) Still, popular modes of exercise come with their own set of environmental concerns, so educate yourself before dropping to give us 20 at the end of your busy day.

For the Fleet of Feet
Those of you whose post-work exercise routine includes an invigorating run may want to consider the implications of inhaling deeply—especially if you live and jog in an urban area.

Your chief outdoor foe is likely ozone, created when the chemicals in car exhaust and other emissions react to sunlight. It lurks mostly during the day, usually hitting its peak in the late afternoon and early evening, and lessens quickly as the sun goes down. Since traffic is usually lighter at night, and factories are likely to be spewing less, it’s likely that nighttime air is cleaner than daytime air. Of course it all depends on weather, geography, traffic intensity, the type of pollution, and so on. Some particulate matter can stick around for weeks, but in general pollution weakens with time.

If your schedule—or safety concerns—don’t allow for nighttime jogging, you still have options. Just pay attention to the local air-quality forecasts and keep a close eye on your body’s reactions as you run, especially if you have asthma or another respiratory condition. Try not to run on days or nights when the air quality is especially bad. If you simply can’t miss a day, ease up a bit: Walk instead of jog, jog instead of sprint.

As for other alternatives, you could create a gym with your friends by combining collective equipment. Or think about joining a local sports league—you get to exercise and socialize all at once. (And whether you win or lose, there’s always a reason to hoist an organic beer or two afterward.)

Low-Impact Exercise

• Walk or bike to work.
• Run up and down the steps of your local museum (just try not to sing the “Rocky” theme song.)
• Work in your garden.
• Do sit-ups while watching Animal Planet.
• Clean out your garage.
• Take your dog for a long walk.
• Chase your kids around the yard.

Advanced Workout

• Bike home from the market with panniers full of fresh food.
• Volunteer to lift sacks of bulk grains at your grocery (you never know).
• Join a group that clears trails in local hiking areas.
• Bench press your composting bin.
• Plant trees with a local arbor organization.
• Push a Hummer into a Prius car lot. Bonus workout: Engage in the ensuing scuffle (don’t forget to guard your face)!

Come On In, the Water’s … Probably Okay

We know some of you go to great lengths to achieve a weekly quota of laps at the pool. Perhaps you’ve noticed the scent of chlorine wafting off your skin for hours afterward and thought, “I stink of chemicals and my hair is turning brittle and green. Could this be harmful?” Well, perk up those swimmer’s ears as we dive into what we know about pools.

Chlorine is used to remove harmful contaminants from water, mostly because it’s
cheap (and because anyone who’s swum in a kid-populated pool is thankful for its mighty
pathogen-zapping powers). But when chlorine reacts with organic matter such as dirt and dandruff, a whole new family of chemicals results: Trihalomethanes (THMs), which hang around in the water and the surrounding air. Their concentration depends on water temperature and the amount of chlorine in the pool.

When swimming in chlorinated water, you have an elevated exposure to this group of chemicals, though the actual risks from such exposure are currently unknown. How long do THMs persist in the body? In the case of the most notorious, chloroform, the answer appears to be: not very long. The U.S. Occupational Safety and Health Administration has set allowable workplace chloroform levels for the standard work week at 50 parts per million. Most pool air will be at that level or higher, but you are only in the pool for an hour or so.

If swimming is your exercise of choice (and if you don’t do it all day long, every day), the associated chemicals aren’t likely to do you in. Be aware that outdoor pools and indoor pools with high ceilings are considered safer than those in low-ceilinged or otherwise tight quarters. Rest assured that swimming is great exercise—and you look totally hot in that Speedo.