Higher than expected levels of air pollution near Ellesmere Port have led to a joint investigation being carried out by four organisations.
Sharp increases in sulphur dioxide have been recorded in Thornton-le-Moors from the neighbouring Essar plant during certain climatic conditions.
Cheshire West and Chester’s environmental protection and public health teams, the Environment Agency, Public Health England and Essar have joined forces to monitor emissions of sulphur dioxide in the Thornton-le-Moors area.
Sulphur dioxide is a major air pollutant with the potential to have a significant impact on people’s health, particularly those with heart or lung problems such as asthma.
News of the joint investigation was given to Tuesday night's meeting of the Ellesmere Port Air Quality Forum by CWAC’s environmental health protection practitioner, Ian Nadin.
Mr Nadin said a monitoring station, established last June, in response to concerns expressed by local residents, had shown that during particular climatic conditions sharp increases in sulphur dioxide are recorded, typically for periods between 15 minutes and two hours.
A year’s monitoring had concluded that the 15-minute standard was likely to be exceeded and would require a detailed assessment involving modelling and further monitoring.
However the data also revealed that the one-hour and 24-hour standards for sulphur dioxide were not being exceeded.
This demonstrates that, although the levels are at times much higher than expected, they are limited and short lived.
A spokesperson for the Environment Agency – responsible for monitoring major installations said: “We are treating this matter seriously and are reviewing the initial findings of the ongoing study.
“We understand that there have been a number of occasions where emissions have been at moderate and higher levels.
“We are working with Essar, Cheshire West and Chester Council and Public Health England to identify the measures the company needs to take to resolve the situation.”
Head of communications and community at Essar Oil UK Limited, Ian Cotton, said: “We work closely with the EA and have an agreed plan for the reduction f sulphur dioxide over time.
“As part of this plan we have invested £20m in a project to convert our site power station to using natural gas, which has significantly reduced our emissions since November 2012.
“Compared to 2011 when the Stanlow site was acquired by Essar, the plan accepted by the EA has already delivered a 43% reduction in our sulphur dioxide emissions with further reductions committed to be delivered by 2017.
“We have made clear already and remain committed to working closely with both the council and the Environment Agency to properly understand the results of this monitoring and agree with both agencies the right course of action going forward.”
For most of the population in a good state of health even moderate air pollution levels are unlikely to have any serious short term effects.
However, adults and children with heart or lung problems such as asthma are at greater risk of symptoms.
Dr Alex Stewart of Public Health England said: “Sulphur dioxide may irritate the nose, throat and airways and can cause coughing, wheezing, shortness of breath, or a tight feeling around the chest.
“The effects of sulphur dioxide are felt very quickly and people at risk of developing symptoms would feel the worst effects in 10 or 15 minutes after breathing it in.
“The effects do not last once the pollution event has moved away in the wind.
“Follow your doctor's usual advice about exercising and managing your condition.”