It is feared Christmas could be ruined for people in several Fife communities if Mossmorran restarts over the holidays.
Fife Ethylene Plant has been shut since August after two of its three boilers failed.
Operator ExxonMobil Chemical initially said it may restart in December but has yet to publish a timetable for the process, expected to involved significant flaring.
Green MSP Mark Ruskell said it is now “worryingly close” to Christmas and urged the company against further flaring disruption over the festive period.
Noise, vibration and light during flaring can cause severe annoyance to those living near the plant, by Cowdenbeath, with people complaining of losing sleep and health issues.
Mr Ruskell said: “Families in the local area have already had their Easter and summer holidays disturbed by prolonged bouts of noise, light and vibrations from flaring at the plant, and it’s utterly unacceptable to think their upcoming Christmas holidays would be ruined in this way too.”
He has written to plant manager Jacob McAllister pleading for the start-up, which it is understood could take two weeks, to avoid Christmas holidays.
He said: “I’m pleased ExxonMobil have taken the time to close the plant down fully and carry out essential maintenance work, but they now need to start sharing with the community their plans for restarting and how much disruption this may cause.
“Their original statements said the plant would be closed until at least November, but we are halfway through the month now and I understand they still have not confirmed with regulators when the start-up process will begin.”
During the three-month closure Shell, which operates adjoining Fife NGL Plant, has taken measures to reduce the amount of ethane it has had to burn off while it is unable to sell it to ExxonMobil for conversion to ethylene.
A spokeman for ExxonMobil Chemical said: “We are currently finalising our re-start timetable and a comprehensive and coordinated public communications plan will be implemented in advance.
“We are very conscious of the needs of our communities and this is being fully factored into our planning.”