The emerald ash borer is supposed to kill trees, not people. But this study found that heart attack risk for women went up 25% when all the trees were killed by this pest. Lessons learned – (1) contact with nature lowers stress in an urban environment, (2) people grieve for lost trees. So cities should plant trees and take care of them. Just not all the same kind of trees, which is a basic principle of resilience. Sure, cities have limited money to spend, but there is a public health case to be made for spending some of it on trees.