Keith Vodden Dr. Douglas Smith - Transports Canada

Ontario Model
d) Additional Pollution
A further social cost of traffic delays caused by collisions is the pollution
associated with extra burning of fossil fuels during the delay. It is widely recognized that
traffic congestion generally, and specifically from collisions, contributes to increased
levels of exposure to vehicle emission-related pollutants. Vehicle drivers and passengers
will feel the negative impacts during traffic delays. The non-driving public may also
experience degradation in the air quality in the area of the collision. Generally, the costs
will be larger in urban areas where roadways are contiguous to large numbers of
residences and persons. There is evidence in the literature that for passengers, pollution
levels inside stopped and idling vehicles, in a group of stopped vehicles, may be from two
to eight times higher than when moving at the speed limit. Any policy-related measures
to reduce collision-related congestion will reduce the health risks to vehicle occupants
and will also reduce general population risk in urban areas.
The extensive literature on air pollution shows that the benefits of risk reduction
related to reduced air quality are substantial. These benefits relate primarily to emissions
of air pollutants such as hydrocarbons (HC), CO, NO x , as well as emissions of
greenhouse gases (GHGs). In this project, we have estimated incremental emissions
related to motor vehicle collisions in Ontario and then valued these additional emissions
using widely cited estimates from the environmental policy literature.
The most widely cited report on air quality and valuing benefits is provided by the
U.S Environmental Protection Agency (EPA, 1999) estimating the benefits of the U.S.
Clean Air Act in preventing premature deaths and illness due to reduced air quality.
For greenhouse gas (GHG) emissions, Pearce (2005) and Tol (2005) provide
estimates of the benefits of emission reductions designed to be used in a cost-benefit
context (that is, to estimate social cost). Their estimates are in the range of C$2.70 to
C$17.50 per tonne of CO 2 emitted. In this project, we have used an average of these
numbers of C$10 per tonne of CO 2 as the value for this parameter. This literature and the
environmental economics literature more generally indicate that these values are likely to
be higher in the future.
The air pollution literature contains many benefit estimates associated with
reductions in Criteria Air Contaminants (CACs). In the case of GHG emissions including
automobiles, this literature suggests that damages related to health effects account for a
large fraction of the total value of what are referred to as ancillary benefits (that is
benefits associated with GHG reductions that go beyond climate change). In this project,
we have used a value of just over C$8 per tonne of CO 2 as the value for the ancillary
benefits (air quality) parameter. The source for this estimate is a study for Resources for
the Future, a leading environmental research institution, by Burtraw and Toman (1998).
This means that the benefits of reducing incremental motor vehicle emissions associated
with traffic incidents consist of C$10 per tonne of CO 2 plus an additional $8 per tonne of
CO 2 to reflect air quality (CAC) benefits (as opposed to CO 2 climate change benefits).
This latter value reflects the damage costs related to CAC emissions per tonne of CO 2 .
TNS Canadian Facts, Social and Policy Research 41