What are two issues related to human activites that change chemicals in the environment?

Two significant issues related to human activities that alter chemicals in the environment are air pollution and water contamination. Air pollution, primarily from industrial emissions and vehicle exhaust, releases harmful chemicals like nitrogen oxides and particulate matter, leading to respiratory problems and climate change. Meanwhile, water contamination from agricultural runoff, industrial discharges, and plastic waste introduces toxic substances into ecosystems, threatening aquatic life and human health. Both issues highlight the urgent need for sustainable practices to mitigate their impact.