Microplastic pollution has been discovered lodged deep in the lungs of living people for the first time. The particles were found in almost all the samples analysed. The scientists said microplastic pollution was now ubiquitous across the planet, making human exposure unavoidable and meaning "there is an increasing concern regarding the hazards" to health. Samples were taken from tissue removed from 13 patients undergoing surgery and microplastics were found in 11 cases. The most common particles were polypropylene, used in plastic packaging and pipes, and PET, used in bottles. Two previous studies had found microplastics at similarly high rates in lung tissue taken during autopsies. People were already known to breathe in the tiny particles, as well as consuming them via food and water. Workers exposed to high levels of microplastics are also known to have developed disease. Microplastics were detected in human blood for the first time in March, showing the particles can travel around the body and may lodge in organs. The impact on health is as yet unknown. But researchers are concerned as microplastics cause damage to human cells in the laboratory and air pollution particles are already known to enter the body and cause millions of early deaths a year. The research, which has been accepted for publication by the journal Science of the Total Environment, used samples of healthy lung tissue.