Search results
Results from the WOW.Com Content Network
Air pollution can occur naturally or be caused by human activities. [4] Air pollution causes around 7 or 8 million deaths each year. [5] [6] It is a significant risk factor for a number of pollution-related diseases, including heart disease, stroke, chronic obstructive pulmonary disease (COPD), asthma and lung cancer.
Within the sciences, the word "contamination" can take on a variety of subtle differences in meaning, whether the contaminant is a solid or a liquid, [3] as well as the variance of environment the contaminant is found to be in. [2] A contaminant may even be more abstract, as in the case of an unwanted energy source that may interfere with a process. [2]
Nonpoint source air pollution affects air quality, from sources such as smokestacks or car tailpipes. Although these pollutants have originated from a point source, the long-range transport ability and multiple sources of the pollutant make it a nonpoint source of pollution; if the discharges were to occur to a body of water or into the ...
The phrase "stop word", which is not in Luhn's 1959 presentation, and the associated terms "stop list" and "stoplist" appear in the literature shortly afterward. [ 5 ] Although it is commonly assumed that stoplists include only the most frequent words in a language, it was C.J. Van Rijsbergen who proposed the first standardized list which was ...