Well, kiddo, E. Cuyler Hammond was a very smart man who studied many things, like smoking and its effects on people's health. He found out that smoking can be really bad for your body because it can cause things like lung cancer and heart disease.
He also studied a lot about how we can make our workplaces safer by reducing things like pollution and hazardous materials. In fact, he even helped make laws that protect workers from getting sick or hurt on the job.
So, basically, E. Cuyler Hammond was a really important person who helped keep us healthy and safe!