An average car, sat idling, can produce exhaust emissions to fill 150 balloons. That's a lot of balloons to imagine puffing away out of the cars idling outside a school for a pickup, say. Other tests have found (pdf) that for any time over 10s fuel use and emissions are always greater when idling than turning off the engine and restarting. Spread the word.

Of course, if you have an electric car this won't apply.

I did draw 150 balloons, but a few of them didn't fit on the page.

Idling

The tragedy of the commons is the all too common outcome of individuals making use of a shared resource and one of the true challenges of our times. The original scenario referred to commons land that soon becomes overgrazed as each individual tries to maximise their value from the share resource. The tragedy is that the overgrazed land is then ruined for all.

We see the effect, perhaps most perniciously, with invisible or hidden shared resources such as taking water from underground aquifers for irrigation, or overfishing of fish stocks in the sea. The same effect is at work with problems such as littering, or washing plastics into the sea, or polluting the atmosphere — while it’s easier for any individual to take another fish, leave their litter on the ground, let pollution run into a river or the sea, or not worry about air pollution, the tragedy is it can have the effect of ruining them for all of us.

When shared resources are moderated or governed fish stocks can be managed to recover, water supplies to replenish or pollution to be naturally treated.

For more, check out this 5 min video on the tragedy of the commons by TED-Ed.

The tragedy of the commons

UPDATE: Since releasing this sketch, which is a fair summary of Kamal Meattle's TED talk, it's been made clear that, though plants do improve air quality, the improvement doesn't compare with a simple change like opening the window.

NASA conducted the original "Plants Improve Air Quality" study in an environment wholly unlike having a few plants in your living room. Listen to James Wong explain the situation in the Sketchplanations botany podcast.

In his 4-minute TED talk, Kamal Meattle explains how to grow your own fresh air inside with just three common house plants. The areca palm works hard during the day, the mother-in-law’s tongue during the night, and the money plant cleans out volatile chemicals. He transformed the air inside a New Delhi office park by filling it with these three plants with seemingly some wonderful health and productivity benefits.

Though plants are undoubtedly lovely to add to your office and home, see the update above for the caution around their potential to freshen your air.

How to grow your own fresh air

The effect you may have noticed where things further in the distance lose their intensity and colour until they fade into the sky. Most often noticeable with hills or mountains, but also in a misty forest as mist, dust, fog or things like pollution increase the effect.

If it’s a blue sky day, the distance will take on a bluer tone like the colour of the sky.

This scene painted from our ascent of Mt Rainier in the Pacific Northwest. And here’s a sunset version.

Atmospheric perspective

The clarity of the night sky. A low number means clear, black and amazing stars. Higher numbers mean gradually more urban environments with increasing light pollution. At 9 you’ll barely spot a star being pretty much in Piccadilly Circus or Times Square.

More detail needed? John Bortle, Light Pollution And Astronomy: The Bortle Dark-Sky Scale, Sky and Telescope, July 18 2006.

Bortle Scale

Sure the big city is worse than the country. But the reality is back streets in a big city are significantly better than the busy streets in a big city, and air pollution changes massively even for small children down at the height of exhausts versus adults standing higher.

So if you’re not about to move to the country you could help yourself a lot nonetheless by taking the back streets (I read this premise in Focus magazine, but can’t find an online link to reference).

Air quality sketches