Got my electrical and mechanical engineering degrees 54 years ago. Designed industrial and commercial airmoving and pollution control systems At one time licensed in 5 states. Again minimal control of air borne submicron particulate by the garbage masks on the market. Of course temperature, humidity and concentration all contribute to the capability of the filter to be useful over time. We all know that! And mechanical dust collectors are not filters.
Market Data 
Markets 
AI
