Diesel truck with sampling equipment attached. |
New
research from North Carolina State University shows that federal
requirements governing diesel engines of new tractor trailer trucks have
resulted in major cuts in emissions of particulate matter (PM) and
nitrogen oxides (NOx)—pollutants that have significant human health and
environmental impacts.
“These
requirements for new emission control technologies have increased costs
for truck owners and operators, and we wanted to know whether there was
any real benefit,” says Dr. Chris Frey, professor of civil,
construction and environmental engineering at NC State and co-author of a
paper describing the research. “We found that there is a huge reduction
in both PM and NOx emissions.”
Frey
and Ph.D. student Gurdas Sandhu used a portable emissions measurement
system to sample exhaust from diesel trucks while the trucks were in use
on roads and highways. The emission requirements apply to new trucks,
meaning that trucks purchased in 2010 and trucks purchased in 1999 were
subject to different emission requirements.
Frey
and Sandhu found that a truck in compliance with 1999 standards emitted
110 g of NOx per gallon of fuel used, and 0.22 g of PM per gallon of
fuel used. NOx is a significant contributor to low-level ozone, which
adversely impacts respiratory health. PM also adversely impacts
respiratory health and, because it is largely made up of black carbon,
also contributes to global climate change.
Trucks
in compliance with newer standards had far lower emissions. For
example, a 2010 truck emitted 2 g of NOx per gallon of fuel—a decrease
of 98%. The PM emissions were 95% lower.
The
NOx reductions stem from the implementation of exhaust gas
recirculation and selective catalytic reduction technologies. The PM
reductions are the result of installing diesel particulate filters into
the tail pipes of diesel trucks.
“While
these technologies are a significant investment for truck owners, this
study shows that they are achieving a remarkable drop in emissions of
contaminants that have meaningful health and environmental
consequences,” Frey says.
Source: North Carolina State University
