Distributions of the natural radionuclide 210 Po and its grandparent 210 Pb along the GP15 Pacific Meridional Transect provide information on scavenging rates of reactive chemical species throughout the water column and fluxes of particulate organic carbon (POC) from the primary production zone (PPZ). 210 Pb is in excess of its grandparent 226 Ra in the upper 400–700 m due to the atmospheric flux of 210 Pb. Mid‐water 210 Pb/ 226 Ra activity ratios are close to radioactive equilibrium (1.0) north of ∼20°N, indicating slow scavenging, but deficiencies at stations near and south of the equator suggest more rapid scavenging associated with a “particle veil” located at the equator and hydrothermal processes at the East Pacific Rise. Scavenging of 210 Pb and 210 Po is evident in the bottom 500–1,000 m at most stations due to enhanced removal in the nepheloid layer. Deficits in the PPZ of 210 Po (relative to 210 Pb) and 210 Pb (relative to 226 Ra decay and the 210 Pb atmospheric flux), together with POC concentrations and particulate 210 Po and 210 Pb activities, are used to calculate export fluxes of POC from the PPZ. 210 Po‐derived POC fluxes on large (>51 μm) particles range from 15.5 ± 1.3 mmol C/m 2 /d to 1.5 ± 0.2 mmol C/m 2 /d and are highest in the Subarctic North Pacific; 210 Pb‐derived fluxes range from 6.7 ± 1.8 mmol C/m 2 /d to 0.2 ± 0.1 mmol C/m 2 /d. Both 210 Po‐ and 210 Pb‐derived POC fluxes are greater than those calculated using the 234 Th proxy, possibly due to different integration times of the radionuclides, considering their different radioactive mean‐lives and scavenging mean residence times.