Throughout the United States, tree cover and types of trees
vary just like pollution. Intensive research has found that trees that give off
small amounts of volatile organic compounds can aid in reducing urban ozone. Trees
have the ability to directly remove air pollutants by absorption via leaf
stomata. Once pollutants are inside of the leaf they disperse to “intercellular
spaces and may be absorbed by water films to form acids or react with
inner-leaf surfaces.” Particulate matter in the atmosphere is directly affected
by trees discharging particles such as pollen, and absorbing particles on the
plant surface and sometimes into the tree. During dry periods, photosynthesis
can be affected due to the build-up of particulate matter on the leaves. During
rainfalls, particulate matter is washed to the soil and eventually returns back
to the atmosphere. The pollution removal formula or flux is equal to the
deposition velocity of the pollutant to the leaf surface multiplied by the
pollutant concentration (F=Vd x C).
Science
Daily reported on the findings of Nowak et al. by stating that air quality only
improved by 1% due to pollutants being removed by trees. This number is
considerable because on average trees “are saving more than 850 human lives a
year and preventing 670,000 incidents of acute respiratory symptoms.” It was found that trees remove more pollutants
in rural versus urban areas, but 80% of Americans live in urban areas where human
health effects are at a greater risk due to the lack of trees. In 2005 it was
estimated that “130,000 PM2.5 related deaths and 4,700 ozone-related deaths
were attributed to air pollution.”
I do
not think Science Daily did a good job at relaying how trees affect air quality and human health to the
public seeing that it is a source for the latest science research news. The
general concept of trees removing pollutants was mentioned along with eye-opening
statistics on human health. However, Science Daily did not mention any
information on the process of how trees remove atmospheric pollutants. The four
pollutants were mentioned but chemical formulas were not given, and volatile
organic compounds were not brought up. The public was not exposed to hardly any scientific terms or methods to how the statistics were calculated.The Science Daily article basically lets
the general public know how important urban trees and forests are to removing atmospheric
pollutants and helping to save lives. However, no countermeasures were brought up on how to stop the removal of trees in urban areas. Overall, I would rate the article 6 out
of 10 due to the lack of vital information Nowak et al. provided.
Science Daily Article:
Nowak et al. 2014. Tree and forest effects on air quality and human health in the United States. Environmental Pollution. 193:119-129.
I agree that a brief mention of the chemistry involved with how trees remove atmospheric pollutants would have been a valuable addition to the article, provided that such information could be told in a way easily understood by the general public.
ReplyDeleteI am also curious about any potential negative human health effects caused by trees, though I am pretty convinced that the benefits trees bring to humans outweigh (to what extent would be another question?) the potential negative human health effects.
This article was focused on tree cover in the U.S.. I think if the author could do some research on tree cover and people health of different countries and compare them, the audience could have a better understanding of how important the trees are.
ReplyDeleteI found this quote to be notable: "In terms of impacts on human health, trees in urban areas are substantially more important than rural trees due to their proximity to people," Nowak said. "We found that in general, the greater the tree cover, the greater the pollution removal, and the greater the removal and population density, the greater the value of human health benefits."
ReplyDelete'Concrete jungle' is a term I'm sure nearly all of us are familiar with. If not, it simply is a colloquial term referring to large urban cities that typically have many large public housing units, businesses and very little green space. It seems that aside from the documented psychological affects of growing up in areas with limited tree coverage, we can now add respiratory health to the list of disparities between those with access to green space in cities and those without.
Cities where such disparities exist between who has access to such green spaces, include Minneapolis, NYC and Washington, D.C.
I saw the mention of photosynthesis being affected by build-up, but are there any other ill effects to trees caused by air pollution. Are the trees suffering in the place of humans while 'cleaning up' the air?
ReplyDeleteAs a runner, it is easy to tell that air pollution decreases when there are more trees. I lived and ran in DC for a few years and would always make an effort to run near trees. There is probably an inverse correlation between trees and cars making it seem like trees are the reason for less pollution, but really it's probably a combination of less cars, more trees.
ReplyDeleteNYC has took to this idea too. It turned an old rail line into a public green space with shrubs, perennials, trees, and grasses: http://www.thehighline.org/about
Just as John mentioned, I would be interested to see if the build-up of pollutants on leaf surfaces impacts the tree negatively at all. Regarding air pollution, however, it would be intriguing to study the efficacy of different types of trees on the removal of pollutants to achieve the greatest result.
ReplyDeleteI thought the science daily article did a decent job of summarizing the research article. It got across the "trees are a good thing" message pretty well, in terms of air pollution. I am particularly interested in the model of the study that is summarized. Especially considering the disperse number of air monitoring stations across much of the west of the continent, there is most likely a very large amount of interpolation across grids. I think this is a good example of the need for more expansive monitoring or better resolution satellite measurements so we can use real data to make these conclusions.
ReplyDeleteIt seems interesting to me how trees are able to remove air pollutants and at the same time emit VOCs which together with NOx form tropospheric ozone under certain circumstances. I'm curious if the type of trees and the specific location (rural/urban) may influence the behavior of trees and the possible health effects associated with that.
ReplyDelete