The latest information about the incident was shared at a public meeting in Salisbury as cordons at nine sites, including the Mill pub, which is part of the Greene King estate, were reinforced as decontamination work continues.
People at the public meeting voiced frustration at the ongoing closures.
Uncertainty over reopening
Ambiguity about when the pub, and other affected sites, will reopen means staff and local residents have been left in limbo.
However, Greene King told the Morning Advertiser "all our team continue to be paid and we have spoken with some of them about the option of working in some of our other pubs in the area”.
“We expect the pub to remain closed for the immediate future while investigations continue and we await further information," the pubco spokesperson said.
Businesses affected by the incident may also be able to claim for some losses on their insurance.
Safe for the public
In a statement Boyd, who is chair of the decontamination science assurance group overseeing the work, said: “Our approach is based on the best scientific evidence and advice to ensure decontamination is carried out in a thorough and careful way. Our number one priority is making these sites safe for the public, so they can be returned to use for the people of Salisbury.
“Thanks to detailed information gathered during the police’s investigation, and our scientific understanding of how the agent works and is spread, we have been able to categorise the likely level of contamination at each site and are drawing up tailored plans.
“Meticulous work is required and we expect it will be a number of months before all sites are fully reopened.”
Boyd is also chief scientific adviser at the Department for the Environment, Food & Rural Affairs.
Government officials were keen to emphasise that the city is safe, despite the latest warnings.
It is believed a liquid form of the nerve agent Novichok was used to poison former spy Sergei Skripal and his daughter Yulia.
Earlier this month, Yulia had recovered enough to be able to leave hospital, while her father is also expected to recover enough to leave hospital, although his progress is far slower.