Which emissions require monitoring?

When implementing an environmental monitoring system for air emissions, a site needs to keep a record of the type and location of emissions.

Types of emissions:

• Venting into atmosphere of intermittent and relief emissions (from normal and abnormal operations)
• Fugitive emissions such as releases from chemical drums that have not had the lids replaced and leaks from seals.
• The origin of each emission should be accompanied with the following information:
• statutory controls and emission limits
• the specifications of the stack: position, diameter and height
• the nature of the stack gases: flow, composition and temperature
• frequency of the emission/discharge

The above information allows the company to calculate the mass rate of each discharge over certain time scales. Other, more complex calculations may be performed depending upon the company's own requirements and in line with its objectives and targets.

An atmospheric emissions monitoring regime should include:

• authorisations: concentration limits and compounds
• an outline of the conditions under which monitoring will take place
• the effect that the emissions will have upon the environment
• the means by which emissions will be recorded and communicated within the company

At some sites the atmospheric emissions may be diverse and large on number.Monitoring requirements may therefore be highly varied for example there may be a requirement for:

• Continuous monitoring, such as for significant, highly variable flows which have an immediate significant environmental impact.
• Discontinuous monitoring, such as that for less significant and less frequent emissions, or where they are measured over a longer period of time and the total emissions are the measure.
• Plume dispersion modelling, environmental monitoring or both may be needed in certain situations.

The guidance of the enforcing authority (local authority and / or Environment Agency) should be sought for all monitoring requirements, in conjunction with Process Guidance Notes where processes are regulated by Local Air Pollution Control (LAPC) or Integrated Pollution Control (IPC).