The Brake Emissions Task Force met on 3 June 2021 to discuss PN measurement approaches. Participants reviewed PM specifications with final comments due by 10 June. RV and AJ presented LINK’s brake PN measurement experience, emphasizing the sampling plane location following EPA Method 1A, flexible hoses for particle transfer, and transfer efficiency results. Most brake systems exhibit multimodal particle size distributions with peaks at approximately 10 nm, 50-100 nm, and 500 nm, with an additional peak at 1.5-2.0 µm not considered crucial for PN concentration. A consensus was reached that large particles shall not be considered for PN measurement. Discussion covered total PN versus Solid PN, with volatiles showing low concentrations across cycles. The next meeting was scheduled for 10 June 2021.