Young and inexperienced workers helped because there was a lot of them and they didn't have to pay them as much as experienced workers and young workers were usually healthy.
Old and experienced workers helped because they would teach inexperienced workers how to do their jobs and they would finish they work faster because they knew what they were doing. They hurt them because they would get paid more and if they were older they would get sick more often and when they don't go to work then that means there is less work getting done and if they died then they had to find someone to fill their position.
Business owners helped because they gave others other people jobs. And they hurt because depending on the business it could cause pollution or even put peoples lives in danger.
U.S. economy hurt because it wasn't as strong as it is today.