18156
For most of the BFRs , the correlations between their concentrations in plants and those in the vapor phase , atmospheric particles , leaf surface particles , and the environmental variables ( temperature , wind speed , and relative humidity ) at this site were in contrast to the results the authors observed at an electronic waste site previously , indicating that ambient air level plays a vital role in the relationships .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 None