Nearly 1,400 complaints have been made to the environmental regulator this year about the Mossmorran chemical plant in Fife.
Sepa have received a rising number of complaints since the start of this year from residents living near the plant raising health concerns.
Symptoms reported by residents have included red itchy eyes, headaches and breathing difficulties.
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NHS Fife is working with the regulator to assess the data.
Louise Biggerstaff, who moved to nearby Crossgates 14 years ago, told BBC Scotland she had started noticing hayfever symptoms she had never experienced before.
"It wasn't until the really big flaring episode at Easter this year that it dawned on me that it was the flaring that was causing it," she said.
"I get burning eyes and can't catch my breath during flaring.
"How I would describe the feeling is the burning that can catch the back of your throat when you are cleaning with bleach mixed with another cleaning product.
"I can now correlate my health symptoms with each flaring event.
"I din't notice a patter at first, but I do now as the flaring has become more frequent and more intense.
"I've also seen the Sepa inspectors testing in nearby fields, but its been up wind which is no good for monitoring the fumes we are having to breath in.
"I'm concerned for my children as I'm scared what they are breathing in and what the long-term effects are."
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ExxonMobil had committed to halting operations at Mossmorran for a month, but the respite from the site was broken by the other chemical plant sharing the site last week.
After the temporary shutdown of ExxonMobil’s neighbouring Fife ethylene plant (FEP) plant, Shell said it was having to adjust its operations to keep processing.
Shell said it expected short periods of elevated flaring, which could be smoky.
The gas plant operators have been given two months by Sepa to come up with a plan to fix the flaring problems.
Mossmorran Action Group chairman James Glen said the campaigners had received hundreds of complaints.
An NHS Fife spokeswoman said: "NHS Fife takes any instance where there may be public health concerns very seriously and we continue to work closely with Sepa and Fife Council on public health issues.
"We recognise that during incidents of unplanned flaring, complaints to Sep's helpline indicate an increase in concern amongst residents about health concerns."