Automotive Engineering - May 2023 - 25

EUROPE'S
BRAKE EMISSIONS FEATURE
DUST
BUSTER
I
The new Euro 7
emissions regulations
for the first time address
particulate emissions caused by braking.
The pending Euro 7 vehicle-emissions regulations include a significant new
sustainability wrinkle: first-ever restrictions for PM emissions from brakes.
by Bill Visnic
n a proposal submitted in November of 2022, the European
Commission detailed its new Euro 7 vehicle emissions standard,
which is widely expected to be approved by the European
Parliament and Council and begin phase-in starting on July 1,
2025. Another phase of emissions legislation is nothing new, but one
critical element of Euro 7 is new to the regulation chessboard: firstever
limits on how much particulate matter (PM) can be generated
by a vehicle's brakes.
This element of Euro 7 has auto and commercial-vehicle brakecomponent
suppliers scurrying. Commercial vehicles are subject to
their own compliance levels as they interpret how the new regulations
will impact their existing technologies and what new solutions
will be required. The proposed Euro 7 regulations also address the
emissions of fine microplastic particles created by tire friction on the
road. As of late Spring 2023, however, the EC had yet to assign permissible
values for tire particulates.
A 2022 European Environment Agency report on air quality in Europe
said that in the EU in 2020, " 96% of the urban population was exposed
to levels of fine particulate matter above the health-based guideline
level set by the World Health Organization. " The EEA added that exposure
to concentrations of fine particulate matter above the 2021
World Health Organization guideline level " resulted in 238,000 premature
deaths in the EU-27. "
A widely cited 2020 study by U.K.-based Emissions Analytics
found that tire particulate emissions can be substantially greater
than particulates now emitted from ever-cleaner vehicle tailpipes.
Foreshadowing, however, the potential impact of the world's expanding
share of EVs (effectively are mandated for EU passenger
vehicles starting in 2035) was a follow-up statement the firm made
in May 2022 regarding EVs in relation to tire PM emissions: " Greater
vehicle mass and [propulsion] torque delivered can lead to rapidly
increasing tire particulate emissions. Half a tonne of battery weight
AUTOMOTIVE ENGINEERING
can result in tire emissions that are almost 400 more
times greater than real-world tailpipe emissions, everything
else being equal. "
Brake emissions typically are sized in the PM10
range (inhalable particulate matter of 10-micron diameter
or smaller; think common dust and pollen) or PM
2.5 (fine dust of 2.5 microns or smaller) band. The
Euro 7 standard seeks to reduce particulate emissions
by 27% - a maximum of 7 mg per kilometer until
2035. Starting in 2035, the brake-emissions limit is
further reduced to 3 mg/km.
Automakers and braking suppliers are muchmore
concerned with 2025 than 2035, said analyst Patricio
Barbale, Chassis Team Lead at S&P Global Mobility.
" The most important impacting factor is the timing -
you have one year, a year-and-a-half, to be compliant. "
Electrification factor
Barbale cited what he believes will be the two central
strategies for Euro 7 brake-emissions compliance: vehicle
electrification and friction-materials innovations.
He explained that the Euro 7 rules allow for a correction
factor that subjects vehicles with varying levels of
electrification to different levels of permitted brake-particulate
emissions. This aspect hasn't been explained in
most broad discussions of the new Euro 7 regulation. " In
theory, the most important thing is that there is a correction
coefficient for the type of engine in the vehicle, "
he said. " If you have an electric vehicle, it is not the same
as an ICE vehicle. If you have a pure electric vehicle, only
15 percent [of total emissions are] considered. "
May 2023 25
iSTOCK PHOTOS/GETTY
https://www.eea.europa.eu//publications/air-quality-in-europe-2022
Automotive Engineering - May 2023

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