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This technique uses the UnSharp Mask (Filter>Sharpen>Unsharp Mask...) to try and remove the haze. 

It appears to be the 'standard' recommended by quite a few people on the web.

Various settings have been published, such as

Light haze removal using Amount 20%, Radius 30, Threshold 4
Stronger haze removal using Amount 20%, Radius 60, Threshold 4

I used Amount 20%, Radius 45, Threshold 0 , but it doesn't seem to be that effective

I also tried these large settings

on a duplicate layer of the image, which produced this effect - ruining the foreground

so I added a layer mask and painted on it to cancel out the change in the foreground and along the wall

to give this final image