In the field of physics, a microparticle is a particle whose size is between 0.1 and 100 μm. More or less degradable or biodegradable microparticles (depending on their nature; mineral, biological, complex, etc.) are present in all compartments of the environment (water, air, soil and pass from one compartment to another, which can also be absorbed or adsorbed by living organisms or mineral matrices). Some are alive (fresh pollen and airborne spores) or mineral (fine sand, dust) ... Mosses and lichens feed on such particles. Microparticles are manufactured by the industry and marketed for various uses. When the particles are toxic or ecotoxic, undesirable, and/or of anthropogenic origin we speak of microparticulate pollution, generally about air pollution (atmosphere, indoor air), but also about the pollution of water made turbid or polluted for example by plastic microparticles. Such microparticles, often resulting from the fragmentation of micro-plastic waste, are found more and more in the marine environment.