DOI: 10.5061/dryad.tmpg4f5bm
title: Data from: Organic composition of ultrafine particles formed from automotive braking

description: 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 (&lt;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.
description: # Data from: Organic composition of ultrafine particles formed from
 automotive braking Name: James Smith ORCID: 0000-0003-4677-8224
 Institution: University of California, Irvine Address: Rowland Hall Room
 317C, Irvine, CA 92697 Email: [jimsmith@uci.edu](mailto:jimsmith@uci.edu)
 Author/Associate or Co-investigator Information Name: Adam Thomas
 Institution: University of California, Irvine Address: Irvine, CA 92697
 Email: [adamet1@uci.edu](mailto:adamet1@uci.edu) Date of data collection:
 2022-08 to 2024-08 Geographic location of data collection: Irvine, CA,
 USA. Information about funding sources that supported the collection of
 the data: California Department of Justice (no. AERTF-221620) National
 Science Foundation (no. 2327825) In addition, this material is based upon
 work supported by the National Science Foundation under Award no. 2324901.
 ## SHARING/ACCESS INFORMATION Licenses/restrictions placed on the data:
 None. Links to publications that cite or use the data: Thomas, A. E.,
 Perraud, V., Lee, M., Rojas, B., Cooke, M. E., Wingen, L. M., Bauer, P.
 S., Dam, M., Finlayson-Pitts, B. J., and Smith, J. N.: Organic composition
 of ultrafine particles formed from automotive braking, Environ. Sci.:
 Process. Impacts. [URL] Recommended citation for this dataset: Smith,
 James and Thomas, Adam (2025), Supporting Data for "Organic
 composition of ultrafine particles formed from automotive braking",
 Dryad [dataset], [URL] ## DATA & FILE OVERVIEW File List:
 LCMS_C_BPEX_neg_mode.csv LCMS_C_BPEX_pos_mode.csv LCMS_C_DYNO_neg_mode.csv
 LCMS_C_DYNO_pos_mode.csv LCMS_C_OVEN_neg_mode.csv LCMS_C_OVEN_pos_mode.csv
 LCMS_C_REP_neg_mode.csv LCMS_C_REP_pos_mode.csv LCMS_SM_BPEX_neg_mode.csv
 LCMS_SM_BPEX_pos_mode.csv LCMS_SM_DYNO_neg_mode.csv
 LCMS_SM_DYNO_pos_mode.csv LCMS_SM_OVEN_neg_mode.csv
 LCMS_SM_OVEN_pos_mode.csv LCMS_SM_REP_neg_mode.csv
 LCMS_SM_REP_pos_mode.csv TDCIMS_C_DYNO_neg_mode.csv
 TDCIMS_C_DYNO_pos_mode.csv TDCIMS_PR_OVEN_200C_neg_mode.csv
 TDCIMS_PR__OVEN_200C_pos_mode.csv TDCIMS_PR_OVEN_250C_neg_mode.csv
 TDCIMS_PR_OVEN_250C_pos_mode.csv TDCIMS_PR_OVEN_300C_neg_mode.csv
 TDCIMS_PR_OVEN_300C_pos_mode.csv TDCIMS_SM_DYNO_neg_mode.csv
 TDCIMS_SM_DYNO_pos_mode.csv ## METHODOLOGICAL INFORMATION Description of
 methods used for collection and processing of data, instrumentation,
 specific software information, experimental conditions, and people
 involved with the experiments can be found in this publication: Thomas, A.
 E., Perraud, V., Lee, M., Rojas, B., Cooke, M. E., Wingen, L. M., Bauer,
 P. S., Dam, M., Finlayson-Pitts, B. J., and Smith, J. N.: Organic
 composition of ultrafine particles formed from automotive braking,
 Environ. Sci.: Process. Impacts. [https://doi.org/10.1039/D5EM00654F]
 Missing data code: n/a ## DATA-SPECIFIC INFORMATION FOR ALL DATA FILES:
 Files: LCMS_C_BPEX_neg_mode.csv LCMS_C_BPEX_pos_mode.csv
 LCMS_C_DYNO_neg_mode.csv LCMS_C_DYNO_pos_mode.csv LCMS_C_OVEN_neg_mode.csv
 LCMS_C_OVEN_pos_mode.csv LCMS_C_REP_neg_mode.csv LCMS_C_REP_pos_mode.csv
 LCMS_SM_BPEX_neg_mode.csv LCMS_SM_BPEX_pos_mode.csv
 LCMS_SM_DYNO_neg_mode.csv LCMS_SM_DYNO_pos_mode.csv
 LCMS_SM_OVEN_neg_mode.csv LCMS_SM_OVEN_pos_mode.csv
 LCMS_SM_REP_neg_mode.csv LCMS_SM_REP_pos_mode.csv Each of the above files
 contains information for all of the species assigned with liquid
 chromatography - mass spectrometry (LCMS) in the referenced study. Sorted
 my molecular mass, each file contains the following columns: signal
 intensity (in counts), monoisotopic mass (in Da), and molecular formula of
 the electrically neutral species. Where relevant, intensity columns also
 include references to the relevant experiment letter as listed in Table
 S1. Each letter corresponds to a separate dynamometer experiment. Short
 descriptions for each relevant experiment letter are summarized below: *
 Experiment J: Brake dynamometer experiment with semi-metallic brakes,
 collecting sub-90 nm particles onto filters for LC-MS analysis (+/-
 modes), trial 1 * Experiment K: Brake dynamometer experiment with
 semi-metallic brakes, collecting sub-90 nm particles onto filters for
 LC-MS analysis (+/- modes), trial 2 * Experiment L: Brake dynamometer
 experiment with ceramic brakes, collecting sub-90 nm particles onto
 filters for LC-MS analysis (+/- modes), trial 1 * Experiment M: Brake
 dynamometer experiment with ceramic brakes, collecting sub-90 nm particles
 onto filters for LC-MS analysis (+/- modes), trial 2 Files are labeled by
 brake (ceramic a.k.a. "C" or semi-metallic a.k.a.
 "SM") and experiment type (fresh brake pad extract a.k.a.
 "BPEX", dynamometer a.k.a. "DYNO", dynamometer
 replicate experiment a.k.a. "REP", or brake pad oven experiment
 a.k.a. OVEN), as well as the electrospray ion polarity with which they
 were collected (negative ion mode a.k.a. "neg_mode" or positive
 ion mode a.k.a. "pos_mode"). All intensities presented are
 background-subtracted. See referenced publication for further details on
 data processing. Files: TDCIMS_C_DYNO_neg_mode.csv
 TDCIMS_C_DYNO_pos_mode.csv TDCIMS_PR_OVEN_200C_neg_mode.csv
 TDCIMS_PR__OVEN_200C_pos_mode.csv TDCIMS_PR_OVEN_250C_neg_mode.csv
 TDCIMS_PR_OVEN_250C_pos_mode.csv TDCIMS_PR_OVEN_300C_neg_mode.csv
 TDCIMS_PR_OVEN_300C_pos_mode.csv TDCIMS_SM_DYNO_neg_mode.csv
 TDCIMS_SM_DYNO_pos_mode.csv Each of the above files contain information
 for all of the species assigned with thermal desorption chemical
 ionization mass spectrometry (TDCIMS) in the referenced study. Sorted my
 molecular mass, each file contains the following columns: mass-to-charge
 ratio (m/z), ion formula, trial signal intensity (in counts), and average
 signal intensity (counts) of the detected species. Where relevant,
 intensity columns also include references to the relevant experiment
 letter as listed in Table S1. Each letter corresponds to a separate
 dynamometer experiment. For TDCIMS oven experiments, data for all three
 trials are included in each csv. Short descriptions for each relevant
 experiment letter are summarized below: * Experiment A: Brake dynamometer
 experiment with semi-metallic brakes, collecting TDCIMS (+/- modes), trial
 1 * Experiment B: Brake dynamometer experiment with semi-metallic brakes,
 collecting TDCIMS (+/- modes), trial 2 * Experiment C: Brake dynamometer
 experiment with semi-metallic brakes, collecting TDCIMS (+/- modes), trial
 3 * Experiment D: Brake dynamometer experiment with ceramic brakes,
 collecting TDCIMS (- mode), trial 1 * Experiment E: Brake dynamometer
 experiment with ceramic brakes, collecting TDCIMS (+ mode), trial 1 *
 Experiment F: Brake dynamometer experiment with ceramic brakes, collecting
 TDCIMS (- mode), trial 2 * Experiment G: Brake dynamometer experiment with
 ceramic brakes, collecting TDCIMS (+ mode), trial 2 * Experiment H: Brake
 dynamometer experiment with ceramic brakes, collecting TDCIMS (- mode),
 trial 3 * Experiment I: Brake dynamometer experiment with ceramic brakes,
 collecting TDCIMS (+ mode), trial 3 Files are labeled by material (ceramic
 brake pad a.k.a. "C", semi-metallic brake pad a.k.a.
 "SM", or phenolic resin a.k.a. "PR") and experiment
 type (dynamometer a.k.a. "DYNO" or phenolic resin oven
 experiment a.k.a. OVEN), as well as the ion polarity with which they were
 collected (negative ion mode a.k.a. "neg_mode" or positive ion
 mode a.k.a. "pos_mode"). For the oven data, the lists are also
 labeled with the oven temperature at which the data was collected in
 Celsius (C). All intensities presented are background-subtracted. See
 referenced publication for further details on data processing.