As Flora says, if you can post the picture, or a small section of it, here then we can see the problem you're describing and see if there's a suitable tutorial or we can give you some advice.
On old black and white photos a haze like that could be silvering (which we do have tutorials on) -- but that wouldn't apply to a 35-year-old color photo.
Most of the discussions we've had on haze relate to reducing atmospheric haze on landscape photographs. Some of the techniques discussed in these threads might work for you too: look at
Blue-atmospheric haze and
Removing the haze from aerial photos. But, as I said, if we can see the specific problem you're asking about it may be easier to identify how to fix the issue.