Air assessment for pesticide registration in Great Britain and Northern Ireland

When applying for pesticide registration in Great Britain and Northern Ireland, you must demonstrate an acceptable environmental risk from short-range transport and provide an assessment of long-range transport potential, according to the data requirements set under Regulation No. (EC) 1107/2009. Active substance data requirements are set under Regulation No. (EC) 283/2013 and plant protection product (PPP) data requirements are set under Regulation No. (EC) 284/2013. Applicants should note that in most cases it will be possible to simply cross refer to the assessment of air conducted as part of active substance approval to meet the requirements for product authorisation.

The data requirements state that you should calculate a predicted environmental concentration in air (PECair) value. In practice, it is often not necessary to calculate a PECair value because exposure to the air is not relevant for the compound. You must provide a reasoned case, justifying why a formal calculation is not necessary.  The case must consider both short- and long-range transport potential.

Short-range transport in air

Guidance on how you should assess the potential for short- and long-range transport is presented in the FOCUS working group report Pesticides in Air: Considerations for Exposure Assessment (SANCO/10553/2006 Rev 2 June 2008).

The following vapour pressure values indicate the potential of a compound to undergo short-range transport in air:

  • vapour pressure ≥ 10-4 Pa (20°C) for volatilisation from soil
  • vapour pressure ≥ 10-5 Pa (20°C) for volatilisation from plants

If the trigger is exceeded and spray drift mitigation measures are needed to reduce exposure to non-target organisms, model calculations of short-range transport and deposition will be required. The model recommended to determine deposition of volatile substances is EVA3 (rev2h). The amount of off-site deposition should be added to exposure arising through spray drift in the surface water exposure assessment.

Long-range transport in air

The potential for long-range transport is needed as part of the assessment of the persistent organic pollutant criteria (POP) (Annex II Section 3.7.1 of Regulation No. (EC) 1107/2009). The compound has the potential to undergo long-range transport in the atmosphere if the calculated DT50 in air is greater than 2 days.

Clearly report how the atmospheric DT50 was calculated. Often the Atkinson calculation is used, which is run using the AOPWINTM programme available through the EPI SuiteTM model. Report the model version and the OH radical concentration used (1.5 x106 radicals/cm3 for a 12-hour period (for fast reacting substances), 0.5 x106 radicals/cm3 for a 24-hour period (for substances with half-lives greater than 24 hours).

If a substance shows potential to undergo long-range transport the other POP criteria must be considered. If a substance meets all three POP criteria it cannot be approved under Regulation (EC) 1107.

For substances that are applied in high amounts the following effects must be considered; global warming potential, ozone depleting potential, photochemical ozone creation potential, accumulation in the troposphere, acidification potential, eutrophication potential.

Refining assessments

Approaches to assessing short and long-range transport potential may be refined using information from experimental studies or monitoring data.  Any studies submitted to refine the assessment of behaviour in air, for example laboratory, wind tunnel or field experiments will be considered on a case-by-case basis. You can submit a draft study protocol so the HSE can confirm whether the design and methodology is appropriate by following the Applicant guide: Consideration of study protocols by HSE


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Updated 2024-04-26