Certain tree species, such as oaks, poplars, and eucalyptus, produce a compound called isoprene. The production of isoprene allows plant leaves to be better adapted to rapid heating from the sun, and can help them tolerate certain airborne compounds, such as ozone. This adaptation has shown to be contributing to the production of certain harmful air pollutants, however. Isoprene can react with hydroxyl radicals in the atmosphere to form the pollutant ozone. Inhalation of ozone can cause lung problems, such as coughing, tightness, pain, and burning of the chest, shortness of breath, and throat irritation. Isoprene can further react with this produced ozone to produce more smog particles, which can exacerbate lung problems such as asthma.
The researchers have also recently discovered that isoprene, when it is altered by exposure to the sun, can also react with nitrogen oxides emitted from the burning of gasoline and from coal burning to produce particulate matter. Scientists discovered the link to plant-produced particulate matter in 2004, but the researchers involved in this study are responsible for making the link between the pollutant and anthropogenic nitrogen oxides. Particulate matter, when inhaled, can cause heart and lung problems, and can also affect air visibility and can make bodies of water more acidic when they are released into the air.
So, should we cut down all of our trees to solve our air pollution problems? The answer is no. The compounds produced by trees are reacting with human-produced compounds, which underscores the need for us to examine our own actions.
Photo courtesy of blmiers2 via Flickr.