nema executive director tom okurut displays a polythene bag measuring 30 micron during a press briefing at nema house. photo by tony rujuta.by john odyek the national environment management authority nema has said the total ban on the importation, local manufacture, sale or use of polythene carrier bags excludes packaging materials used for food stuffs such as bread and milk products, exports, for medical and industrial use.other categories excluded are polythene packaging materials for research, science, sanitation, construction materials.