# Me vs my car - who pollutes most? **URL:** \ **Category:** Factual Questions\ **Created:** [May 26, 2006, 5:00pm UTC](https://boards.straightdope.com/t/me-vs-my-car-who-pollutes-most/358339 "2006-05-26T17:00:24Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Twotwofive](https://avatars.discourse-cdn.com/v4/letter/t/a87d85/32.png) [@Twotwofive](https://boards.straightdope.com/u/Twotwofive)\ **Post date:** [May 26, 2006, 5:00pm UTC](https://boards.straightdope.com/t/me-vs-my-car-who-pollutes-most/358339/1 "2006-05-26T17:00:24Z")
All these threads cropping up about CO2 pollution, hybrid cars, etc reminded me of a claim Jeremy Clarkson (loved and loathed in equal measure by Brits; presumably unknown elsewhere, but try Google if you care) once made, which is that a person produces more CO2 on the running machine at the gym than their car does driving them to and from the gym. I haven’t included the cite, as he probably made the stat up on the spot. However, I’d be interested to hear if anyone thinks there’s any truth to it. For reference, my car produces 210g/km of CO2 and does about a 3 mile round trip to the gym (apologies for the mismatched units). I spend about 20mins on the treadmill while I’m at the gym, and cover 4km or so. (And please don’t tell me I could accomplish the same by just running to gym - it’s usually raining here, and there’s a very steep hill.) ---
**Author:** ![Rocket](https://avatars.discourse-cdn.com/v4/letter/r/e79b87/32.png) [@Rocket](https://boards.straightdope.com/u/Rocket)\ **Post date:** [May 26, 2006, 7:27pm UTC](https://boards.straightdope.com/t/me-vs-my-car-who-pollutes-most/358339/2 "2006-05-26T19:27:38Z")
Here’s a quick and dirty estimate for you, using the following assumptions; You car has a catalytic converter and gets 20 mpg and runs on gas 19.4 lbs of CO2 are produced from 1 gallon of gasoline (source EPA) Your exercise respiratory rate is 42 per minute Your volume per respiration is 0.5 litres (adult 20-30 y.o. avg) 5% of the volume exhaled is CO2 For a 3 mile round trip to the gym your car produces; 3 mi/20 mpg \* 19.4 lbs/gal = 2.91 lbs of CO2 For your 20 minutes on the treadmill you produce; 42 resp/min \* 20 minutes \* 0.5 litres/resp \* 0.05 (% CO2) = 21 litres CO2 = 0.021 cubic meters CO2 = 0.0915 lbs CO2 Someone should check my assumptions and math since I did this quickly, but it looks like there is no contest. The car produces much more. ---
**Author:** ![thirdname](https://avatars.discourse-cdn.com/v4/letter/t/d07c76/32.png) [@thirdname](https://boards.straightdope.com/u/thirdname)\ **Post date:** [May 26, 2006, 11:36pm UTC](https://boards.straightdope.com/t/me-vs-my-car-who-pollutes-most/358339/3 "2006-05-26T23:36:49Z")
My thought is that you should try pushing a car if you haven’t before. Compare your efforts to that of the internal combustion engine, and that should tell you who is burning more kilocalories. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 27, 2006, 12:58am UTC](https://boards.straightdope.com/t/me-vs-my-car-who-pollutes-most/358339/4 "2006-05-27T00:58:42Z")
**Rocket** I think your numbers are off for the car. In the OP he says that his car produces 210g/Km of CO2 and does a 3 mile round trip. converting miles to Km 3 \*.6 = 1.8 210g \* 1.8 = 378 grams According to Google that is 0.833347351 pounds I am not sure about your numbers for a human, but these appear to be correct for the car. ---
**Author:** ![Dervorin](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dervorin](https://boards.straightdope.com/u/Dervorin)\ **Post date:** [May 27, 2006, 11:40am UTC](https://boards.straightdope.com/t/me-vs-my-car-who-pollutes-most/358339/5 "2006-05-27T11:40:25Z")
> [@Rick](#): > > **Rocket** I think your numbers are off for the car. In the OP he says that his car produces 210g/Km of CO2 and does a 3 mile round trip. > converting miles to Km 3 \*.6 = 1.8 > 210g \* 1.8 = 378 grams > According to Google that is 0.833347351 pounds > > I am not sure about your numbers for a human, but these appear to be correct for the car. Err… miles to km is \*1.6, not /1.6. 3 miles = 5km (roughly). So 210g \* 5 = 1050g, or just over a kilogram. Without google, I know that’s about 2.3lb. **Rocket** , where did you get the 0.5 l / breath figure from? I believe that’s accurate for someone at rest, but during heavy exercise it goes up dramatically - to about 2 or 3l per breath. That would then be 125l CO2, which works out to 0.5lb, give or take. Still very heavily (snerk) on the side of the car. Jeremy Clarkson may be a great driver and a very funny TV show host, but I strongly suspect his talent for hyperbole outweighs his scientific accuracy in this particular instance. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [May 27, 2006, 12:04pm UTC](https://boards.straightdope.com/t/me-vs-my-car-who-pollutes-most/358339/6 "2006-05-27T12:04:32Z")
Firstly, 210g/km seems pretty high - my 1.6 16v Ford Focus puts out 160g/km. What do you drive? A Hummer? 😉 Secondly, according to [this](http://cdiac.ornl.gov/pns/faq.html), each human puts out 1kg CO[sub]2[/sub] per day. So it sounds like Mr Clarkson was indulging in some hyperbole for fun. Wouldn’t be the first time. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 27, 2006, 2:10pm UTC](https://boards.straightdope.com/t/me-vs-my-car-who-pollutes-most/358339/7 "2006-05-27T14:10:11Z")
> [@Dervorin](#): > > Err… miles to km is \*1.6, not /1.6. Of course it is. I am a :wally I think my brain is starting to rot. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 27, 2006, 2:32pm UTC](https://boards.straightdope.com/t/me-vs-my-car-who-pollutes-most/358339/8 "2006-05-27T14:32:05Z")
BTW the thread I read right after this one [degenerated into a discussion of cars and gas mileage](http://boards.straightdope.com/sdmb/showthread.php?t=373150) , anyway there was a link to the [smart car](http://www.thesmart.ca/index.cfm?id=4730) CO2 emissions is 90g/Km So 90 \* 5 = 450g Less than half a kilo The numbers are closer.