The way people eat all around the world — including in the US — is a major risk factor for pandemics, too. That’s because we eat a ton of meat, and the vast majority of it comes from factory farms. In these huge industrialized facilities that supply more than 90 percent of meat globally — and around 99 percent of America’s meat — animals are tightly packed together and live under harsh and unsanitary conditions. Bird flu is caused by viruses and it’s a massive risk coming out of factor