ABSTRACTPersistent organic pollutants (POPs) include pesticides which are organochlorine compounds, such as aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, alpha and beta hexachlorocyclohexane (also by-products), chlordecone, and lindane. Industrial chemicals such as PCBs, hexachlorobenzene (also a pesticide), hexabromobiphenyl, hexa- and heptabromodiphenyl ether (commercial octabromodiphenyl ether), pentachlorobenzene, perfluorooctane sulfonic acid and its salts perfluorooctane sulfonyl fluoride, tetra- and pentabromodiphenyl ether (commercial pentabromodiphenyl ether), and unintentional by-product compounds, such as polychlorinated dioxins and furans (PCDD/Fs). The international community has repeatedly called for urgent global action to reduce and eventually eliminate the release of these chemicals. However, the emission characteristics, control technologies, atmosphere transport and toxicities of dioxins are not well investigated. This special issue in Aerosol and Air Quality Research features 24 papers submitted by researchers from Australia, Canada, China, Italy, Japan, Malaysia, Norway, Switzerland, Taiwan, Thailand, United Kingdom, USA and Vietnam. In these studies, the characteristics of POPs are investigated in air filters, tree bark, house dust, road dust, ambient air, fugitive nanoparticle, stack flue gas, fly ash, and serum samples.