Was it widely known/covered? Was there outrage and condemnation? Did Saddam and his allies attempt to suppress evidence of the attacks?
First it was denial. The US urged its representative at the UN to pressure other members of the UN to "take no decision" with respect to Iranian complaints about Iraqi chemical weapons use. http://nsarchive.gwu.edu/NSAEBB/NSAEBB82/iraq47.pdf
Then it was obfuscation. It was Iran that first disclosed the atrocity at Halabja, when Iranian news reporters reached the scene. The the US promoted the idea that 'both sides' were using chemical weapons and that the deaths in Halabja was actually the fault of Iran. http://www.nytimes.com/2003/01/17/opinion/17iht-edjoost_ed3_.html
This bit of misinformation and propaganda is still occasionally mentioned today, but in reality Iran did not use chemical weapons during the Iran-Iraq war because Khomeini prohibited the use of WMDs on moral grounds, though it had developed the capacity to to make chemical weapons. http://cns.miis.edu/archive/cns/programs/dc/briefs/030701.htm
More
http://cns.miis.edu/archive/cns/programs/dc/briefs/030701.htm
http://www.amazon.com/Poisonous-Affair-America-Gassing-Halabja/dp/0521876869