[2][1] Ooms’ active participation in the negotiation of a permanent, multilateral ban on chemical weapons, began in 1969 when he joined the Netherlands' delegation to the Eighteen Nation Committee on Disarmament (ENCD) in Geneva as a technical adviser.
Ooms became the only CD delegate that continuously participated over the full 20 years of negotiations, which culminated in the adoption of the Chemical Weapons Convention by the United Nations General Assembly in 1992.
He attended the 1980 International School of Disarmament and Research on Conflicts[3] and later served on the Dutch delegation to the preparatory commission that founded the Organisation for the Prohibition of Chemical Weapons with its headquarters in The Hague.
In 1991, Ooms was appointed to the United Nations Special Commission, at that time forming to oversee Iraq's renunciation of weapons of mass destruction.
On 27 April 2006, Prime Minister Jan-Peter Balkenende unveiled a photograph of Ooms during his visit on the first observance of the Day of Remembrance for All Victims of Chemical Warfare.