Evaluation of Land Use Regression Models for Nitrogen Dioxide and Benzene in Four US Cities

Table 3

Model 𝑅² and significant variables (5% level) in NO₂ and benzene LURs.

Model 𝑅^2 (%)	El Paso		Detroit		Dallas		Cleveland
	NO2	benzene	NO2	benzene	NO2	benzene	NO2
	97	93	82	43	34^a/48^b	72^a/49^b	96
Distance to nearest low traffic road
Distance to nearest medium traffic road			▼ ^c	▼	▲/		▲
Distance to nearest high traffic road			▲^d		▼/	▼/
Traffic intensity within set buffers	▲				▲/▲	▲/	▲
Length of local roads within set buffers							▼
Length of secondary roads within set buffers							▼
Open area within set radii							▼
Population density within census block group or set radii	▲	▲		▲
Point source (categorical or continuous)	▼ and ▲^e	▼ and ▲	▼	▼	▼/▼		♦^f
Elevation
Distance to nearest international border crossing	▼	▼	▼	▲
Season							♦
Seasonal interaction of point source and population density categories							♦

^aSummer.
^bWinter.
^cSignificant (5% level) decrease.
^dSignificant (5% level) increase.
^eDecrease followed by increase.
^fCategorical variables (significant 5% level).