Chertok 2004 - “Comparison of Air Pollution Exposure for Five Commuting Modes in Sydney – Car, Train, Bus, Bicycle and Walking”

Chertok, Michael ; Voukelatos, Alexander ; Sheppeard, Vicky ; and Rissel, Chris
“Comparison of Air Pollution Exposure for Five Commuting Modes in Sydney – Car, Train, Bus, Bicycle and Walking”
Health Promotion Journal of Australia
April 2004; v.15,n.1; pp.63-67
On the Web (pdf)
Relevance: high

The study measured the BTEX pollutant and NO2 exposure of 44 subjects on their regular daily commutes, each lasting at least 30 minutes each way.  Car commuters were exposed to the highest levels of BTEX pollutants, while bus commuters were exposed to the highest levels of NO2.  Train (light and heavy rail) commuters were exposed to the lowest levels of all pollutants measured.  Walking and cycling commuters were exposed to significantly lower levels of BTEX than car commuters and of NO2 than bus commuters. 

Over 40 years of commuting, a motorist would inhale 400 mg of benzene compared with 126 mg for a train commuter (assuming a commute of 79 mins/day, 5 days/week, 48 weeks for 40 years, adult respiratory rate 0.83 L/min).

The table below shows the mean concentration levels found for various commuting modes, standardized for duration of travel (also see attractive chart in article).

Mode	Benzene (ppb)	NO2 (ppb)
Car (n=9)	12.29	29.70
Bus (n=4)	6.94	44.30
Cycle (n=7)	6.17	24.58
Train (n=11)	3.77	14.85
Walk (n=9)	5.70	26.08

Where most studies compare exposure on fixed routes, not taking into account that actual travel patterns may differ among drivers and walkers, by contrast this study does not control for route choice but rather tracks exposure from actual travel patterns along actual routes.

Comments

[Eric de Place]

Good stuff. Fairly small sample size though. I'd hesitate to point out the high NO-2 exposure to bus riders based on the experience of just 4 commuters.

Also, I wonder if there are important differences between emissions and maintenance standards in Austrailia and the US? What about fuels?

[John]

This doesnt help at all for my 6th grade report, except for the part, "Over 40 years of commuting, a motorist would inhale 400 mg of benzene compared with 126 mg for a train commuter."

PEACE