Did some more research. To be certain particles escape if any mask does not fit tightly. This site has done testing of various materials for efficacy in filtering particles larger than 1.0 microns. They use a Henderson apparatus similar to the set up of Cambridge researchers which they link. The virus causing covid-19 is 1.2 microns.
Testing Materials for Coronavirus
Coughing spews particles greater than 5 microns and we know symptomatic infected people who cough can infect people. The million dollar question is whether aerosols which are smaller than 5 microns but bigger than 1.2 microns cause infections. If aerosols can infect us asymptomatic people with the disease can infect others through breathing and talking. As this next article demonstrates there is a lot of research that needs to be done before we know that answer.
Can Covid-19 be spread through breathing and talking.
Based on these two articles and given that people are social distancing six feet at best, a distance which is arbitrary and not scientifically verified to be safe, I would absolutely recommend people wear even cloth masks over no mask at all.