Why, near underground heating mains, leaves on trees retain their green color longer and fall off later?

Why, near underground heating mains, leaves on trees retain their green color longer and fall off later? Does this have negative consequences for trees?

Near heating mains, trees do shed their leaves later. It’s all because of the heat. Trees feel cooling and climate change later, so leaf shedding occurs later. This has some effect on trees. Plants shed their leaves for a reason. They remove all accumulated toxins there. If the frost hits faster than the leaves have time to change color, then the toxins will remain in the tree. Leaves die due to the crystallization of water in the cells. But this does not always happen and basically there is no big negative effect on plants.