Map of ozone air quality standards (ppb) set for the protection of human health. Air quality standards for different countries/nations, based on daily maximum 8 hour average ozone (MDA8). No standard indicates that information was available to indicate that no standard was in use or defined. NA indicates that no information on standards was found, or that standards may exist but are not 8-hour standards and therefore are not included. DOI: https://doi.org/10.1525/elementa.273.f1