The inspection teams have also coordinated the breakdown of thousands of metric tons of unused chemical munitions as part of the ongoing effort to eliminate those stockpiles, according to OPCW officials.
That declaration, along with the ongoing dismantlement of the weapon sites, are part of a U.S.-Russian disarmament deal reached earlier this year.
Assad's forces have battered rebel fighters in Syria during the course of the three-year war, hammering those anti-government forces with a barrage of heavy weaponry, including chemical weapons.
U.S. forces were poised to begin military strikes against Assad in retaliation for his use of chemical weapons against rebel positions near Damascus.
While Congress debated whether to grant the White House authority to intervene in Syria, the Russian-proposed disarmament deal put those strikes on indefinite hold.
So far, Assad has complied with the terms of the U.N.-mandated disarmament deal, offering up a comprehensive assessment of his chemical stockpiles and allowing international inspectors into the country.
Secretary of State John Kerry praised the Assad regime for its compliance with the disarmament plan.
"I'm not going to vouch ... for what happens months down the road, but it's a good beginning, and we should welcome a good beginning," Kerry said in a joint press briefing with Russian Foreign Minister Sergei Lavrov in October.