Ultra-Low Penetration Air filter

A type of air filter that can remove from the air at least 99.999% of dust, pollen, mold, bacteria and any airborne particles with a minimum particle penetration size of 120 nanometres (ultrafine particles).

Unidirectional flow

An airflow moving in a single direction, in a robust and uniform manner, and at sufficient speed, to reproducibly sweep particles away from the critical processing or testing area.


The quality or state of being the same, the quality or state of being uniform or identical.

United Nations Institute for Training and Research (UNITAR)

Dedicated training arm of the United Nations system. It provides training and capacity development activities to assist mainly developing countries with special attention to Least Developed Countries (LDCs), Small Island Developing States (SIDS) and other groups and communities who are most vulnerable


The eruption of red marks on the skin that are usually accompanied by itching. This condition can be caused by an allergy (e.g., to a food or drug), stress, infection, or physical agents such as heat or cold. Also known as hives.