Unfortunately, most furnace filters are slid in place without an airtight seal, which allows air to pass around the filters. This problem is worse for the higher-efficiency MERV filters because of the increase in air resistance.
Common Cause is a network of people working to help rebalance cultural values to create a more equitable, sustainable and democratic society. 1  We are all shaped by our culture.
Component cause: An individual event, condition, or characteristic required by a given sufficient cause.  Necessary cause: A component cause present in every sufficient cause.  Often there are many sufficient causes, which may produce a given effect.