Wash. Rev. Code § 70.74.310
Any person other than a lawfully constituted peace officer of this state who shall deposit, leave, place, spray, scatter, spread, or throw in any building, or any place, or who shall counsel, aid, assist, encourage, incite, or direct any other person or persons to deposit, leave, place, spray, scatter, spread, or throw, in any building or place, or who shall have in his or her possession for the purpose of, and with the intent of depositing, leaving, placing, spraying, scattering, spreading, or throwing, in any building or place, or of counseling, aiding, assisting, encouraging, inciting, or directing any other person or persons to deposit, leave, place, spray, scatter, spread, or throw, any stink bomb, stink paint, tear bomb, tear shell, explosive, or flame-producing device, or any other device, material, chemical, or substance, which, when exploded or opened, or without such exploding or opening, by reason of its offensive and pungent odor, does or will annoy, injure, endanger, or inconvenience any person or persons, shall be guilty of a gross misdemeanor: PROVIDED, That this section shall not apply to persons in the military service, actually engaged in the performance of military duties, pursuant to orders from competent authority nor to any property owner or person acting under his or her authority in providing protection against the commission of a felony.
RCW 70.74.310