It appears your HC, CO, and NO rose from 25 mph to 15 mph. I
am not sure which is the greatest concern, but for starters
I'd be looking at replacing the PCV valve ($20 or so part;
easy to replace on your car; can make a big difference);
doing a complete tuenup (use only OEM ignition wires, plugs,
distributor cap and rotor; put in a new air filter and fuel
filter; check the timing); Then I'd assess the EGR system
(assuming your Civic is carbureted; is it?).

The above is taken from

http://www.aircare.ca/index.php?repinfo-glossary.php

http://www.interro.com/techgas.html#anchoreleven

You go the particular compound emitted, then click or read
on causes of why it is out of spec, etc. There are more
fixes than the ones I list above.

Updates welcome. This should be interesting (though sorry
about your troubles).

ok, but you need to post what the passing levels are as well.
presumably it's failing NO and CO.  high NO on its own means either
combustion temp is too high or the cat is ineffective.  if the latter,
as it could easily be, especially since the 15mph test is done /before/
the 25mph test, that the cat was not up to working temp.  particularly
as you also have high CO.  did you leave the motor running while you
were waiting to go up on the dyno?  if the motor was off, the cat cooled
down.  the tech should not have accepted the vehicle as test ready if
the cat was not up to working temp.

if it was just NO, and if the vehicle's automatic [you don't say], check
and clean the egr valve.  also, replace the plugs, leads, distributor
cap and rotor arm.  pcv valve and decent quality oil helps too.  also,
check the timing with the ecu over-ride jumper in place.  it takes
ignition timing back to base to allow adjustments to be correct.  making
sure the valve lash is correct helps too.  and coolant level.

lastly, go to a test-only station.  the "test & repair" places know all
the tricks to have you spend money with them.  dmv has a list online.

Your CO2 is way too low. And all your other numbers are quite high. Either
the cat wasn't warmed up sufficiently, or it's cheapo aftermarket junk that
only lasts a couple of years.

In addition, you could have a problem with clogged EGR passages.