Subject: Summer T-shirt; is white actually cooler than navy blue?

At work we wear a uniform T-shirt (navy blue, white crest).  I have suggested 
that during the hot summer months a white T-shirt (with blue crest) would be 
more appropriate due to the fact that it would be cooler.  We spend equal 
amounts of time outside on firetrucks and inside air conditioned firehall.  I 
also wonder if lighter colors would affect comfort during very humid conditions?

Re: Summer T-shirt; is white actually cooler than navy blue?