ITU‑R WP3L is a part of ITU Study Group 3 which con­cerns itself with radiowave prop­a­ga­tion. WP3L is more specif­i­cal­ly con­cerned with ionos­pher­ic prop­a­ga­tion and radio noise.

A sig­nif­i­cant ref­er­ence doc­u­ment main­tained by WP3L is the ITU‑R Rec­om­men­da­tion P.372 “Radio Noise” which is a sig­nif­i­cant ref­er­ence doc­u­ment when plan­ning radio ser­vices and con­sid­er­ing the impact of sources of interference.

IARU is involved in dis­cus­sions about the updat­ing of P.372, draw­ing heav­i­ly on work done is some of its soci­eties to mea­sure cur­rent noise lev­els to pro­fes­sion­al standards.