Testing by MIT of many of the protective face masks distributed by the Massachusetts Emergency Management Agency to police and other frontline workers has revealed they were deficient.

One type of mask distributed by the state filtered only about 28% of airborne particles, the Boston Globe reports.

According to state data, all of the respirator masks distributed to public safety entities were from China and flown to the U.S. on the New England Patriots plane in early April, WBUR reports.