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Calculating the `Big Kill'

Smoke and Mirrors: The EPA's Flawed Study of Environmental Tobacco Smoke and Lung Cancer












23 times more toxic than in a house?

Ever heard the one about tobacco smoke in a vehicle being “23 times more toxic than in a house”? You’ll see it rear its ugly head in jurisdictions where tobacco control groups are pushing for a ban on smoking in cars.

In Ontario, Canada, the Ontario Medical Association is given as the reliable source of this data. The problem is the OMA cites a newspaper article as the source of this ‘evidence.’

An exhaustive search for scientific support for this claim has found two studies that have measured in-vehicle particulate concentrations associated with tobacco smoke. One 2007 paper by Ott el al in and a 2002 paper by Offermann et al presented at  a 2002 International Conference on Indoor Air Quality and Climate. The later paper by Offermann is the likely source of the ’23 times’ claim since Offermann claims tobacco smoke in vehicles is “25 times more toxic than in a house.

The 2007 Ott study was funded by Flight Attendant Medical Research Institute (FAMRI). FAMRI is “funded through a settlement from a class action lawsuit against tobacco companies on behalf of flight attendants who sustained health problems due to exposure to second hand smoke in their job.

The 2004 Offermann study was funded by “the Tobacco Free Project, San Francisco Department of Public Health, paid for by Proposition 99, the 1988 Tobacco Tax Initiative, under Contract 89-97927.

  • Both studies measured particulate matter inside a vehicle with a smoker and found:
  • particle levels smaller than 3 microns peaked between 2000 and 3000 ug/m3 for a very few seconds when a cigarette was first lit. These peak measurements occurred only when the vehicle’s windows were closed and the fan was turned off with a resultant low air exchange rate (about five complete air exchanges per hour). The average ug/m3 while the cigarette was smoked in this sealed vehicle was around 1200.
  • turning the fan in the vehicles on increased the air exchange rate to about one complete exchange every minute thus reducing the particulate count inside the vehicle. The average ug/m3 during while the cigarette was smoked in this sealed vehicle with the fan on was around 700.
  • opening one window (3” in Ott’s study) increased the air exchange rate even further with an additional decrease in particulates inside the vehicle. The average ug/m3 during while the cigarette was smoked in this windows open/fan off vehicle was around 92.
  • The actual volume of the inside compartment of the vehicle is a critical measurement when determining concentrations. Offermann’s 2004 study estimated the volume inside a ‘1996 mini-van’ at 2.0 m3. Ott’s 2007 study estimated the volume of the much smaller ‘2005 Toyota Corolla’ at 2.6 m3.

In addition to their questionable objectivity both studies suffer serious methodological flaws.

  • the difficulty in accurately determining the actual volume of air inside a vehicle as evidenced by the estimated air volume inside the compact Toyota Corolla being greater than the volume of air inside the mini-van.
  • the particulate measurements obtained by Offermann incorrectly refers to particulates as ets. He counted all particles under 3 microns in diameter.
  • Equipment cannot differentiate between tobacco smoke, road dust, pollen, diesel exhaust, paint pigment, carpet fibres, skin cells, soot and viruses that are less than 3 microns diameter. Therefore his measurements include other sources of particulates inside the vehicle. How much did these others sources contribute?
  • no particle measurements were taken inside a car with non-smoking passengers to determine background levels of particulates inside the vehicle. Any movement can be expected to send particulate matter from engine exhaust, carpets, clothes, skin and a myriad of other sources into the air of the vehicle.
  • the Dusttrak measuring equipment used in the Offermann’s 2004 study is well known to give readings up to 3 times higher than actual(8).
  • humidity also gives readings higher(9) than actual and no adjustment was made to account for this (ie drying tubes). In addition, the highest measurements were recorded inside a vehicle with windows closed and fan off which one would expect would increase humidity inside the vehicle.
  • Offerman’s measurements of air quality inside a vehicle were not used to compare to air quality inside a home. Rather the air quality for vehicles was estimated and then compared to the air of a home. A far more appropriate comparison would be to OSHA indoor air quality standards which consider up to 5000 ug/m3 per hour for an 8 hour day/40 hour work week over the course of a workers employment life to be safe.
  • Another more suitable comparison would be fine particulates inside a bus which have been measured to peak at 1732 ug/m3 in the middle of the bus with extraordinarily high peaks around 12000 ug/m3 near the door to the bus
  • both studies compare air quality inside a vehicle to outdoor air quality standards. The irrationality of this is apparent. Compare the EPA’s outdoor air quality standards for particulate matter under 2.5 microns (currently 35 ug/m3 over 24 hours) to OSHA indoor air quality standards that ensures a safe indoor workplace. If EPA standards dictated workplace air quality no workplace would be considered safe.

The Canadian Charter of Rights and Freedoms protects Canadians from the unreasonable interference of government in the lives of people in a free and democratic society. While the Charter does allow the government to legally limit an individual's freedoms it does so within clearly defined reasonable limits. Surely the evidence above that is now being used to press for limits to Canadian’s privacy and existing freedoms cannot be helpful to any sincere considerations to limit these civil liberties.