Other factors that negatively impact the environment include toxic emissions and the pollution of water, land and air. Pollutants also adversely affect human health, causing health conditions and diseases such as cholera, heart disease, cancer, cystic fibrosis, and respiratory tract and eye irritation. Pollutants have led to increased mortality rates.
To maintain a clean environment, people need to reduce the use of toxic materials, conserve water and energy, dispose of garbage properly, recycle waste products, purchase recycled products, invest in green energy and drive fuel-efficient cars with reduced carbon dioxide emissions.
Sound plays a key role in the ecosystem. The National Park Service indicates that the acoustical environment affects wildlife in terms of its ability to find adequate habitat, avoid predators, protect young, locate food and attract a mate. As noise pollution from human beings in the form of motor vehicle and airplane traffic among other causes increases, wildlife is forced to adapt in ways that are not sustainable. For example researchers discovered that the males of a particular frog species began calling at a higher pitch in an effort to distinguish their calls from traffic noise. However, the females of that species prefer a lower pitch, which means there is less successful mating within the species in general.
The Environmental Protection Agency defines noise pollution as any sound that is disturbing or unwanted. In human terms this usually includes sounds that disrupt sleep or conversation or otherwise erode a person's quality of life. The same holds true for wildlife, only with far more dire consequences.
According to the World Health Organization, air pollution accounts for as many as seven million premature deaths worldwide each year. This includes not only outdoor air pollution from vehicles, industrial sources and power generation, but also indoor air pollution from burning fuel for cooking or heat. Most of these deaths occur in the developing world, in countries where environmental regulations are less strict and the populations lack access to cleaner energy options.
Another way in which air pollution can be dangerous is when it contains particulates and volatile organic compounds. These particles can represent threats in many different ways, ranging from chemical effects on the body to low-level radiation, depending on the source. Breathing in these particles in smog can pose a significant health risk even beyond a respiratory problem. The nitric oxide and sulfur dioxide created when fossil fuels combust can also contribute to smog and acid rain.
