Changes

[[Reagan|Ronald Reagan]] did not say, "[[Trees]] cause smog" but rather, "Trees cause more [[pollution]] than [[automobiles]] do." In a discussion of smoggy [[city]] skies, it could be easy to overlook what Reagan was actually referring to:

[[Reagan|Ronald Reagan]] did not say, "[[Trees]] cause smog" but rather, "Trees cause more [[pollution]] than [[automobiles]] do." In a discussion of smoggy [[city]] skies, it could be easy to overlook what Reagan was actually referring to:

*According to a study by the University of Helsinki, coniferous [[forest|forests]]--that is to say, those composed of trees such as pines--release nitrogen oxides into the atmosphere that combine with other pollutants to form smog.  

*According to a study by the University of Helsinki, coniferous [[forest]]s—that is to say, those composed of trees such as pines—release nitrogen oxides into the atmosphere that combine with other pollutants to form smog.  

*Nitrogen oxides (NOx), along with [[hydrocarbon]] gases and sunlight, are the three ingredients needed to make photochemical smog that clogs the skies of many urban centers, as well as [[acid rain]]. The researchers were surprised to find NOx produced by the [[pine|pine needles]], and that levels rose when shoots were exposed to ultraviolet radiation from the [[Sun]]. While the amount produced was insignificant on a local scale, "our findings suggest that global NOx from boreal coniferous forests may be comparable to those produced by worldwide [[industry|industrial]] and traffic sources," said the authors. <ref>http://wiki.answers.com/Q/What_are_some_environmental_issues_with_pine_trees</ref>

*Nitrogen oxides (NOx), along with [[hydrocarbon]] gases and sunlight, are the three ingredients needed to make photochemical smog that clogs the skies of many urban centers, as well as [[acid rain]]. The researchers were surprised to find NOx produced by the [[pine|pine needles]], and that levels rose when shoots were exposed to ultraviolet radiation from the [[Sun]]. While the amount produced was insignificant on a local scale, "our findings suggest that global NOx from boreal coniferous forests may be comparable to those produced by worldwide [[industry|industrial]] and traffic sources," said the authors.<ref>http://wiki.answers.com/Q/What_are_some_environmental_issues_with_pine_trees</ref>

== References ==

== References ==