Air Quality Report 6
Summary
This sixth interim report has provided opportunity for review of all the monitoring data gathered since February 2024 to be considered.
The recorded concentrations of hydrogen sulphide measured at each diffusion tube placed within surrounding communities have continued to be recorded well below the lifetime exposure criteria value of 1ppb. The levels currently observed are the same as those found at other points in South Wales. This diffusion tube monitoring will continue.
It is apparent from the repeated use of the Jerome instrument at different times of day over several months that Hydrogen Sulphide is not persistently detectable over such time-frames. At many monitoring positions on different occasions during recent months, the Jerome has not found detectable levels of Hydrogen Sulphide. Given that such low levels are now being found the plan, at this stage, is to cease routine monitoring with the Jerome at the end of September 2024.
During this monitoring period, diffusion tubes have once again been used to assess for the presence of VOCs. Low concentration levels continue to be found and it appears that Hydrogen Sulphide is still the most useful target compound for trying to detect the presence of odours. The use of these tubes will also, therefore, cease.
Moving forward, the community monitoring programme will therefore focus on the measurement of Hydrogen Sulphide using diffusion tubes at D1-D12 along with the data gathered by Pembrokeshire County Council at the fixed position monitor located at Spittal School. This flexible strategy will be subject to continual review.
References
Ref 1. U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry (ATSDR), Toxicological profile for Hydrogen Sulphide, 2006.
Ref 2. U.S. Environmental Protection Agency Reference Concentration for Hydrogen Sulphide.
Ref 3. EH40/2005 Workplace exposure limits (Fourth Edition 2020)
Acknowledgements
Many thanks to Pembrokeshire Council for facilitating access to Spittal School.