Merv (, , Marv), formerly Achaemenid Satrapy of Margiana, and later Alexandria (Ἀλεξάνδρεια) and Antiochia in Margiana , was a major oasis-city in Central Asia, on the historical Silk Road, located near today's Mary in Turkmenistan.

Minimum efficiency reporting value, commonly known as MERV rating, is a measurement scale designed in 1987 by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of air filters.