Table 1.

Environmental determinants computed to explore the intra-urban variation of grass pollen concentrations.

Environmental variable	Unit	Description	Source
TC brightness	Index	Land use/cover with high albedo (overall brightness of the image)	Landsat TM5
TC greenness	Index	Amount of photosynthetically active green vegetation	Landsat TM5
Wasteland	m2	Unmanaged grasslands (e.g., meadows and power lines)	SLICES land use classification
Park	m2	Managed grasslands (e.g., urban parks and sports fields)	SLICES land use classification
Field	m2	Cultivated fields (e.g., wheat and barley fields)	SLICES land use classification
Deciduous forest	m2	Broadleaf trees (e.g., birch, alder, and maple)	CORINE land cover database
Mixed forest	m2	Broadleaf trees and conifers (pine and spruce)	CORINE land cover database
Urban land use	m2	Urban land use classes (e.g., high density residential, commercial, industrial, and traffic areas)	SLICES land use classification
Abbreviations: TC, tasseled cap; TM5, Thematic Mapper 5. The Landsat data were from 2010 (http://earthexplorer.usgs.gov/), SLICES data were from 2010 [National Land Survey of Finland (http://www.maanmittauslaitos.fi/en/kartat)], and CORINE from 2006 (Finnish Environmental Institute 2009).