Why too many cars are making us sick

Why too many cars are making us sick

We have more cars per household than ever before

The latest NSW Household Transport Survey shows that the number of multiple-car-owning households in Sydney is growing steadily, and has been doing so for the past decade. At the same time, the number of households who live car free has been gradually decreasing.


Well, too many cars cause local congestion, noise and smog, and global pollution – we’ve talked about that before.

But this slow car-creep is also bad for our health. Because the more cars your household owns, the less likely you are to walk anywhere.

A person living in a car-free household uses their legs to go someplace an average of 2.6 times a day. If there is one car in the household, this figure drops by nearly half, to 1.4 walking trips. If there are three cars in your household, then you are likely to have days when you don’t walk anywhere at all (0.7 walking trips a day).

Car dependency contributes to sedentary disease and obesity

Instead of walking, we are sitting. The average Sydneysider spends at least 37 minutes a day in a car. For some inner-city dwellers it’s less; for others with a long commute it is much more. You can do some face yoga or kegels while you’re sitting in traffic, but it’s not exactly cardio. Much as it may raise your blood pressure, car time is sedentary time.


Well, the Heart Foundation notes that physical inactivity is a significant risk factor for cardiovascular disease and other chronic diseases, such as type 2 diabetes and some cancers.


Well, if these far-off risks don’t bother you youngsters, there’s also the fact that sitting in your cars can make you fat. Driving less helps you lose weight and stay fit, without really trying.

Even a small daily imbalance between our daily energy intake and output – say, the energy we save by driving instead of making that 15-minute walk to the shops – can lead to significant weight gain over time. (If you’re interested in the scary details of exactly how many grams slip onto your hips each year, check out this detailed study (PDF) from the European Union).

OK – but isn’t car-sharing just a way to drive more?

Well – no. The Heart Foundation’s “Blueprint for an Active Australia” recommends providing financial incentives to make active choices cheaper and easier, and encouraging more walking, cycling and public transport use.

Peer-to-peer car sharing ticks both boxes. The financial incentives work to encourage both owners and borrowers to use cars selectively, and to choose more active transport when possible.

Car-sharing changes the default. You think differently. You ask “Is driving the best way to get where I want to go today?” instead of just jumping in the car that’s in the driveway.

The City of Sydney estimates that one car share vehicle car replaces up to seven private cars, since people only use car share when it makes sense to drive, relying on walking, cycling and public transport for many of their trips.

Should we get rid of cars altogether, then?

Maybe! But we’re not quite there yet.

Active transport researcher Lyn Sloman, in her book Carsick, explains why with the concept of the “40:40:20 rule” for car trips. Her research shows that:

  • About 40% of trips could be made without a car using existing infrastructure.
  • 40% of car trips need to be made by car now, but could be made without a car if better infrastructure were provided – for example, better public transport or more cycling lanes.
  • The remaining 20% of trips would need to be made by car in any case – for example, taking an elderly relative to the doctor or getting bulky goods home from the shops.
  • Car-sharing provides the bridge to a less car-dependent life. With access to a car for those 20% to 60% of trips that require it, people are free not to own one. And without a car in the driveway (or, if you’re a car owner, knowing that you could earn some money if you leave your car at home), you’re less likely to drive.

Not going far? Don’t use a car

Transport statistics tell us that the most common trip distance for city-dwellers is between 2-5 kilometres.

Around a third of trips up to one kilometre; two thirds of trips between 1-2 kilometres, and four-fifths trips between 2 and 5 kilometres, are made by car.

In contrast, only about 4% of the people who borrow cars through Car Next Door drive less than 5km. We know from speaking to our members that they use cars when they need to – to take stuff to a photo shoot, or go on a date, or get to somewhere that would take three buses and a yak otherwise – and the rest of the time they walk, ride, or take public transport. Using a car is a conscious choice, not a reflex.

This is one reason why the City of Sydney supports car-sharing, and has a target of 10 per cent of households having at least one member of a car share organisation by 2016.

Save the world, one step at a time

Yes, it’s true – using your lovely legs can save the world:

“Increasing levels of physical activity will not just benefit the health system … [it] will also provide gains in relation to climate change, traffic congestion, social cohesion and community safety.” (DR Lyn Roberts AM, CEO –National Heart Foundation)

What more could you ask?

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