Gladiatorial games, part 13

(… continued from Gladiatorial games, part 12, posted on 29 Jan 2016).

Whilst the descriptions in the Noise Policy Statement for England (NPSE) and on the Planning Practice Guidance (PPG) website that I reviewed in part 12 will be helpful to those trying to decide on a suitable level for the LOAEL daytime threshold to apply to a particular project, they stop a long way short of making recommendations of suitable values. In contrast, those seeking to decide on an appropriate level for a night-time LOAEL can find very precise instruction in the World Health Organisation (WHO) Publication Night Noise Guidelines for Europe (NNGL), which is that “40dB Lnight,outside is equivalent to the LOAEL for night noise” (see footnote 1).

Given that it is recommended by the WHO, you would think that the adoption of 40dB LpAeq,8hr as LOAEL night was a no-brainer, and that is certainly the course that HS2 Ltd has taken. However, it appears to me that it is questionable whether the level recommended by the WHO is consistent with the requirements of the NPSE on two grounds that I pointed to in part 12. Firstly, the NPSE appears to set its stall against the prescription of “a single objective noise-based measure that is mandatory”, and secondly the NPSE is concerned with adverse effects on health and quality of life, rather than just health effects as is the case with the NNGL (see footnote 2). Considering these caveats, it was something of a surprise that neither Rick Methold, expert acoustics witness for Chiltern District Council, nor Doug Sharps, expert acoustics witness for the HS2 Action Alliance, challenged the 40dB night LOAEL threshold value.

As I reported in part 12, due to the publication date of the relevant document pre-dating the general use of LOAEL by acousticians, the WHO currently makes no recommendation for a daytime LOAEL threshold value. This has not discouraged HS2 Ltd from apparently citing the WHO in support of the choice of 50dB LpAeq,16hr for the daytime LOAEL threshold (see footnote 3):

“For the daytime level, the information used to support the WHO Guidelines for Community Noise indicate that daytime sound levels of less than 50 dB LpAeq cause little or no serious annoyance in the community.”

Supported by the footnote:

“World Health Organisation (1999) Guidelines for Community Noise. World Health Organisation, Geneva.”

I have already pointed out – in footnote 1 to part 8 of this blog series – that the phrasing of this paragraph is, probably intentionally, vague and glosses over the important difference, as pointed out by Mr Methold, that the WHO is referring to the total noise from all sources, whereas HS2 Ltd confine themselves to comparing only noise from HS2 sources with the LOAEL threshold; this discrepancy is something of which Mr Methold repeatedly reminded the Select Committee during his evidence.

Notwithstanding this important objection, Mr Methold also pointed out, under cross-examination, that the phrase “cause little or no serious annoyance in the community” appears in a 1995 precursor to the WHO 1999 Guidelines for Community Noise, but is not in the later document (see footnote 4). In response, however, the Promoter’s Lead Counsel, Tim Mould QC, was able to furnish the Select Committee with this, not dissimilar, observation from the 1999 document (see footnote 5):

“During the daytime, few people are seriously annoyed by activities with L[Aeq] levels below 55[dB] or moderately annoyed with L[Aeq] levels below 50[dB].”

Curiously, another observation from Guidelines for Community Noise that was read out before the Committee passed without any comment, but could perhaps be seen as an endorsement by the WHO of a much lower LOAEL threshold value (see footnote 6):

“… most countries in Europe have adopted 40[dB LAeq] as the maximum allowable level for new developments. Indeed, the lower value should be considered the maximum allowable sound pressure level for all new developments whenever feasible.”

Apart from the important caveat already mentioned that the WHO comments apply to the total noise from all sources, not just the noise introduced from a new source, the WHO document expresses the following additional qualifications, with references to the appropriate paragraphs in Guidelines for Community Noise given in brackets:

  • That some identifiable groups within the overall population may be more vulnerable to noise impacts (fourth paragraph of section 4.1).
  • That speech intelligibility may be impaired at lower levels than those recommended by considerations of annoyance (first paragraph of section 4.2.1).
  • LAeq,T is only an appropriate parameter for measuring continuing sounds. When there are distinct events to the noise, measures of the individual events should also be employed (first paragraph of section 2.1.5).
  • The effects of noise that is discontinuous will depend upon the average frequency of individual noise events (first paragraph of section 2.3.2).
  • That susceptibility to noise is likely to be higher in the evening, not only at night (third paragraph of section 4.2.7).
  • Sensitivity to noise may vary between countries (first paragraph of section 4.2.7).
  • That equal levels of noise from different types of source lead to different degrees of annoyance. This is because the capacity of noise to cause annoyance depends upon its characteristics, including its spectral components, peak to mean level ratio and variation with time including whether there are any distinct patterns, (section 2.3.2, section 2.3.5 and section 4.2.7).
  • That the annoyance response may depend on the subject activity that the noise is disrupting (section 4.2.8).
  • That the annoyance effect of a particular noise will depend on how much that noise exceeds the level of ambient noise (section 2.3.4).
  • The WHO regards noise from high speed trains as giving rise to “special noise problems” (third paragraph of section 2.2.2).

All of which, you might think, is more than enough scope for variability to illustrate why the decision by HS2 Ltd to use 50dB LpAeq,16hr could be contentious, but Mr Methold provided yet another reason why he disputed the appropriateness of this value. He told the Select Committee that this figure had been derived from “a highly annoyed curve” (see footnote 7), but my attempt to explain what he meant will have to wait until the next posting.

(To be continued …)

Footnotes:

  1. See the paragraph immediately below Table 5.5 on page 109 of Night Noise Guidelines for Europe, World Health Organization (WHO) Regional Office for Europe, October 2009.
  2. Although you could argue, with some justification I think, that sleep deprivation can be directly linked to health effects, whereas quality of life issues become much more of a concern with daytime annoyance.
  3. The quoted text is paragraph 14 and footnote 8 of Appendix A to Information Paper E20. The 50dB LOAEL threshold value is specified in Table 1 in Appendix B to that document.
  4. See the sixth paragraph of section 10.6.5 of Berglund, B and Lindvall, T, Community Noise, Center for Sensory Research, Stockholm and World Health Organisation, 1995.
  5. See paragraph 514 of the transcript of the morning session of the HS2 Select Committee that was held on Wednesday 4thNovember 2015. The original source is the third paragraph of section 4.2.7 of Guidelines for Community Noise, World Health Organisation, 1999.
  6. See paragraph 548 of the transcript of the morning session of the HS2 Select Committee that was held on Wednesday 4thNovember 2015. The original source is the second paragraph of section 4.3.1 of Guidelines for Community Noise.
  7. See paragraph 399 of the transcript of the morning session of the HS2 Select Committee that was held on Wednesday 4thNovember 2015.

Acknowledgement: I wish to thank Michael Woodhouse for his suggestions and comments, which I have found invaluable in preparing this series of blogs.

Important Note: The record of the proceedings of the HS2 Select Committee from which the quote reproduced in this blog has been taken is an uncorrected transcript of evidence, which is not yet an approved formal record. Neither witnesses nor Members have had the opportunity to correct the record in such instances, and it may therefore be subject to changes being made in the light of any such corrections being requested.

 

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: