Pollutants can affect man with direct effects such as: acute effects from exposure to a toxic pollutant reaching man through air, water or food; long-term effects due to prolonged exposure to a pollutant at levels lower than those giving rise to overt toxic effects; synergistic interaction between pollutants or between a pollutant and malnutrition or disease; genetic effects that are manifested in future generations. Indirect effects on man may result from reduction of the food supply or deterioration of the environment. Such effects include: damage to plants and animals; disruption of ecological cycles such that a previously harmless species becomes a pest; damage to the human habitat (air pollutants that destroy forests and corrode buildings); water pollutants that destroy the recreational value of inland waters; alteration of the global climate (this is considered to be a future threat).
Technical progress and mechanization has in recent decades led to a rapid increase in noise. About every fifth worker in Germany is subjected to a noise level of 90 dB or over. The atmosphere is being polluted by dust, smoke and exhaust gases from industry, motor vehicles and domestic heating. In the former Soviet Union fifty million people live in areas where the air pollution levels are 10 times the minimum health standard. In the Urals the city of Nizhny Tagil, for example, industrial enterprises emit nearly 700,000 tons of poisonous substances into the air every year.
[Developing countries] Although air, water and noise pollution are not yet matters of primary concern in urban areas of developing countries, such problems will grow more severe as these countries move toward their goals of economic development. Generally the devices and regulations presently in force to control pollution in developed countries are not applied to industrial processes in developing countries with equal efficiency or stringency. In an effort to provide increased economic well-being, environmental safeguards are neglected. Water supplies are not only contaminated with human wastes, but grow increasingly toxic as they receive the effluent from expanding industries. Air pollution increases with the material well-being of the urban population and emanates from power plants, industry, space heating and the growing number of motor vehicles.