Poor air quality is a common problem in many urban areas . It can lead to decreased human health , damage to landscape materials and ecosystem processes , and reduced visibility . The urban forest can help improve air quality by reducing air temperature , directly removing pollutants from the air , and reducing energy consumption in buildings , which consequently reduces air pollutant emissions from the power sources . Trees also emit volatile organic compounds that can contribute to ozone formation . However , integrative studies have revealed that an increase in tree cover leads to reduced ozone formation ( Nowak and Dwyer 2000 ).
Pollution removal 1 by trees in Mount Auburn Cemetery Sample Plots was estimated using field data and recent available pollution and weather data available . Pollution removal was greatest for ozone ( Figure 7 ). It is estimated that trees remove 703.7 pounds of air pollution ( ozone ( O3 ), carbon monoxide ( CO ), nitrogen dioxide ( NO2 ), particulate matter less than 2.5 microns ( PM2.5 ) 2 , and sulfur dioxide ( SO2 )) per year with an associated value of $ 17.9 thousand ( see Appendix I for more details ).
1 Particulate matter less than 10 microns is a significant air pollutant . Given that i-Tree Eco analyzes particulate matter less than 2.5 microns ( PM2.5 ) which is a subset of PM10 , PM10 has not been included in this analysis . PM2.5 is generally more relevant in discussions concerning air pollution effects on human health .
2 Trees remove PM2.5 when particulate matter is deposited on leaf surfaces . This deposited PM2.5 can be resuspended to the atmosphere or removed during rain
events and dissolved or transferred to the soil . This combination of events can lead to positive or negative pollution removal and value depending on various atmospheric factors ( see Appendix I for more details ).
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I-Tree Report of Ecosystem Analysis at Mount Auburn Cemetery Insert to the Climate Action and Sustainability Plan