how do human activities such as deforestation affected the environment?

Deforestation has many effects, including decreasing oxygen levels (and increasing greenhouse gases), elevated risk of soil erosion, and the destruction of animal habitats.

how does the environment affect us in return?

Several specific environmental issues can impede human health and wellness. These issues include chemical pollution, air pollution, climate change, disease-causing microbes, lack of access to health care, poor infrastructure, and poor water quality.