On nonlinear methods in environmental and biological measurements

This paper presents relations between real-world phenomena, sensors and measurement methods that without applied simplifications are generally nonlinear. The article is built upon real-world examples which directly affect quality of human life or straightforwardly refer to life itself. First, the health of a human being is investigated. Next, attention is moved towards measurements of water and air quality. We conclude with an observation that commonly demanded linear characteristics of a measurement system are feasible with nonlinear methods of signal and data processing.