"the first sentence of the ref says
A chemical weapons watchdog says chlorine may have been used in April's attack on the Syrian city of Douma.
so.... how does this square with no the OP headline ? "
If by 'ref' you mean the BBC link jno provided to an article titled "Syria war: 'Possible chlorine' at Douma attack site - watchdog", which is not the link SpiceRack provided in the OP, this BBC article provides no proof of this assertion in that article.
Or perhaps you see the BBC as some impartial refer(h)ee(hee).
Nowhere in the actual report does it state "chlorine may have been used in April's attack on the Syrian city of Douma." Maybe the BBC were alluding to another 'watchdog' or cat(belling).
https://www.opcw.org/fileadmin/OPCW/S_series/2018/en/s-1645-2018_e_.pdf
But the actual report light into "the inspectors were denied access to the site for so long"
'2.2 The FFM team was not able to enter Douma for almost a week after its arrival, owing
to the high security risks to the team, which included the presence of unexploded
ordnance, explosives, and sleeper cells still suspected of being active in Douma. On
18 April 2018, during a reconnaissance visit to two sites of interest, the security detail
was confronted by a hostile crowd and came under fire from small arms and a hand
grenade that exploded. The incident reportedly resulted in two fatalities and one
injury.
2.3 On 21 April 2018, after security concerns had been addressed, the FFM team
conducted its first visit to one of the alleged sites of interest, and it was deemed an
acceptable risk to enter Douma. The FFM team deployed four additional times to
other sites of interest over the following 10 days,...'
'6. SECURITY AND ACCESS TO THE SITES OF THE ALLEGED INCIDENTS
6.1 Given the recent military activities and the volatile situation in Douma at the time of
the FFM deployment, security and safety considerations were of paramount
importance. Considerable time and effort were invested in discussions and planning to
mitigate the inherent security risks to the FFM team and others deploying into
Douma. According to Syrian Arab Republic and Russian Military Police
representatives, there were a number of unacceptable risks to the team, including
mines and explosives that still needed to be cleared, a risk of explosions, and sleeper
cells still suspected of being active in Douma. This assessment was shared by the
representative of the United Nations Department of Safety and Security (UNDSS).'
'6.2 At the outset, the formal position of the FFM team, as instructed by the Director-General, was that security of the mission should be the responsibility of the Syrian Arab Republic.'
Loading the blame gun.