Data from: Organic composition of ultrafine particles formed from automotive braking

Non-exhaust emissions (e.g., automotive brake and tire wear) are quickly
replacing exhaust emissions as the dominant traffic particulate pollutant.
Despite this, a thorough exploration of the composition of particles from
these sources is lacking, particularly the organic fraction. Due to their
unique health implications, knowledge of the composition of ultrafine
particles (<100 nm in diameter) is of particular interest. Here we
report on the size-selected organic composition of ultrafine particles
nucleated during high brake temperature conditions generated using a
custom brake dynamometer system and two common brake pad types.
 Using high resolution mass spectrometry, we find that the
organic composition of these particles is dominated by species containing
oxygen (CHO) and nitrogen (CHN/CHON). Many of these compounds are
unsaturated and are attributed to the thermal degradation of resin
material used in the pad formulation.  Other abundant compounds
include various glycols and amines, several of which are unequivocally
identified and discussed as potential marker compounds for brake wear
emissions.  A significant fraction of highly oxidized, low
volatility species observed in ultrafine particles could not be
conclusively attributed to the thermal degradation of the brake material,
indicating the presence of chemical pathways unique to the frictional
heating process. This emphasizes the importance of using a brake
dynamometer to generate brake wear particles as opposed to other
strategies.