Sepa said it had been advised by operators of the facility at Mossmorran in Fife that elevated flaring had ceased but ground flaring would continue for a "short period".
A formal investigation was launched on Thursday into the unplanned flaring following an unprecedented number of complaints from members of the public.
More than 750 reports have been received since Easter Sunday, with people citing a chemical smell and a loud rumbling noise.
The incident comes after ExxonMobil Chemical Ltd was served with final warning letters last year regarding flaring, which was found to be "preventable and unacceptable".
Sepa said it would continue to monitor air quality and noise over the weekend.
On Monday, Sepa chief executive Terry A'Hearn will hold discussions with plant manager Jacob McAlister.
Mr A'Hearn said: "While the Mossmorran complex is a major industrial facility where this type of flaring is a legitimate safety mechanism, this is happening too often and the level and extent of flaring is wholly unacceptable.
"Understanding the impact of flaring provided by local communities, families and individuals is vitally important and, as such, we would encourage people to continue to report impacts directly to us online at www.sepa.org.uk/report or via our 24-hour pollution hotline on 0800 807060.
"We'll continue to make information available as quickly as possible, including a further update on monitoring results early next week."
Mr McAlister said on Thursday that operators were committed to working constructively with Sepa and were already undertaking their own investigation.
The flaring has illuminated the sky over Edinburgh for a number of nights - with some comparing it to a scene from hit films Lord of the Rings.