EA tightens industrial air environment assessment levels

The Environment Agency has confirmed a series of changes to the pollutant benchmarks used in air emissions risk assessments, with acceptable levels for some substances substantially tightened.

In 2022 and 2023, the Environment Agency (EA) ran two consultations on proposals for a series of new or updated environment assessment levels (EALs) used in air emissions risk assessments.

EALs represent a pollutant concentration in ambient air at which no “appreciable risks or minimal risks to human health are expected”, they are used by the EA to judge the acceptability of proposed emissions to air from industrial processes, and their relative contribution to the environment. 

The aim of EALs, according to the EA, is to protect public health from emissions of chemical pollutants from a permitted activity. 

There are currently 88 substances with EALs. The latest update means that the EA has now updated or reviewed EALs for a further 13 substances.

These new values will now apply for all new permit applications and for all substantially changed permits. For all existing permits, the new values will be implemented when permits are subject to sector review, on a case-by-case basis depending on the circumstances. 

In response to the consultation, concerns were raised that any stringent changes must be “proportionate”. Specifically, one respondent noted that in some cases mercury may be present naturally in raw materials or fuels used in industrial processes and therefore is unlikely that it can be removed entirely from a production process. 

They warned that high costs associated with “disproportionate environmental regulation” may lead international companies to relocate production outside of the UK. 

In response, the EA said that working with the UK Health Security Agency, it has a “responsibility to protect public health” and that they are aware that international agreements are looking to lower mercury emission levels. “We therefore will work with operators to identify solutions that address environmental, health and economic issues.”

In its consultation response, the Institute of Air Quality Management (IAQM) highlighted that the new EALs for some substances have been “substantially tightened”. For example, the long term EAL for copper has been reduced by a factor of about 1,000 and and the EAL for methyl chloride has been reduced by a factor of approximately 100 compared to the previous EALs. 

The institute also highlighted that a number of annual mean EALs have been replaced with 24 hour mean long term EALs. It said the EA should “advise or provide guidance” on how it expects operators to assess their operations against these updated long-term EALs.  

In general, the IAQM said that modelling of short-term peak (e.g. maximum 24 hour mean) concentrations are subject to “greater uncertainty” than modelling annual mean concentrations. This change, they said, “has the potential to increase uncertainty in model forecasts.” 

In response, the EA highlighted that long-term EALs are “usually based on adverse health effects observed following repeated daily exposures, often averaged, over longer time periods of weeks, months and years”.  

It highlighted that the mean daily concentration averaged over a longer duration should not exceed the long-term EAL and the duration over which daily concentrations are averaged should reflect the nature of the activity.

To help determine future substances to consider, the EA asked consultees to list any remaining EALs from the air emissions risk assessment guidance that are relevant to their permit applications.

A range of chemical chemical substances were suggested for prioritising of EAL updating, these include: 

  • antimony

  • manganese

  • vanadium

  • cobalt

  • lead

  • tin

  • NOx (nitric oxide and nitrogen dioxide)

  • sulphur dioxide

  • hydrogen fluoride

  • ammonia

  • carbon monoxide

  • ammonia

  • acetaldehyde

  • antimony

  • formaldehyde (annual mean)

  • PCBs

  • nitric oxide

  • acetone

  • butane

  • diethyl ketone

  • methyl ethyl ketone

  • methyl propyl ketone, methanol, 1-propanol, 2-propanol, and toluene

  • acrylic acid

  • acrylonitrile

  • methanol

  • phenol

The EA has said that it is considering “all of these suggested substances for the next phase of EAL development”, however, it said it will be unable to update EALs for all compounds “due to resource limitations” and so they will “prioritise accordingly”.

The agency also highlighted that some of these substances already have an established regulatory limit value, for example lead, nitrogen dioxide, carbon monoxide and sulphur dioxide.