- The Chairman announced that Lord Toby Harris had resigned from the
Committee and thanked him in absentia for his contribution during
his time on the Committee.
Minutes
- There were no comments on the minutes. They would be placed on the
website shortly.
Matters arising
- The Committee’s statements on Papers by Dr Andrea Venn and Dr Rob
McConnell (on asthma and air pollution) and on London Underground Tunnel
Dust had been placed on the website and the 2001 Annual Report was ready
to go on the website. The statement on unflued gas fires would be placed
on the website soon after incorporation of a few final comments. The
Committee requested information on the number of hits on the website
after new items were placed there as an indication of interest in each
item. It was agreed that a summary of the hit frequencies would be circulated
with agenda documents twice a year.
- The Secretariat announced that a small amount of extra research money
had been found in order to fund a research project on neuropsychological
effects of carbon monoxide.
Ozone – Effects of Long-term Exposure
- The Committee considered that the evidence for effects of long-term
exposure on respiratory symptoms would be more convincing if there was
more consistency in the symptoms affected but did not consider the evidence
could be dismissed. The evidence against an effect of long-term exposure
on mortality was stronger with the recent publication of further follow-up
of the American Cancer Society cohort (Pope et al (2002) JAMA
287:1132-1141). It was considered that a ‘watching brief’ should
be kept on the long-term effects of ozone but that, at present, there
was insufficient evidence for quantification and therefore no need for
further work on whether there was a threshold for any long term effect.
Ozone – Effects on lung function
- It was agreed that there was a tiny but strongly statistically significant
effect of ozone on lung function. It was noted that shifting the mean
effect by a small amount could have more important implications for
a small number of people at the tail of the population distribution.
The Committee did not regard lung function as an appropriate endpoint
for quantification as the changes were not necessarily of clinical significance.
The Committee considered that there was no strong evidence in favour
of a threshold although it was noted that, in some cases, the slopes
of the dose-response function were reduced at lower ozone levels. This
finding lent some plausibility to the increase in deaths and hospital
admissions at lower ozone levels found in the time-series studies although
it was acknowledged that deaths and hospital admissions could be the
result of entirely different mechanisms.
Ozone – Further analysis of mortality and hospital
admissions
- The Committee agreed that the small number of studies on seasonal
differences with seasonal concentrations of ozone available were not
informative about a possible threshold for effects of ozone. For the
plots of coefficients for ozone and all cause mortality against mean
ozone levels, evidence for a threshold (lower slopes at lower ozone
levels) was not found. This needed to be interpreted cautiously as there
was considerable overlap in the ozone ranges and the coefficients could
be imposing a linear shape on thresholded data. The Committee considered
it would be worth testing the statistical significance of the trend
and performing a similar analysis for the other health outcomes.
- An overview of the Committee’s findings on ozone would be drafted
for the next meeting.
Openness
- The Committee noted the information provided by the Secretariat on
the Environmental Information Regulations and the Freedom of Information
Act and the clauses for Committee discussion in the Code of Practice
for Scientific Advisory Committees. The Committee suggested that, if
a consensus could not be reached, any dissenting views should be noted
in the main text of a Committee document not just in a footnote. It
was suggested that a stand-alone list of the references for an issue
considered by the Committee should be made public. A single list of
stakeholders was not considered helpful as this would vary across different
issues but a list of those consulted could be included in Committee
reports. The Committee was content with current arrangements for dealing
with the media. The Chairman agreed to write to the Chairmen of the
COC and COT regarding exchange of information between the Committees
as relevant issues came up.
Sub-group on asthma and air pollution
- Sections of the sub-group report were being drafted and would come
round to the Committee for comment in early December. These comments
would be incorporated in time for the February meeting.
Sub-group on air pollution and heart disease
- The next meeting of this group would be in January. Sections were
being drafted.
Talk by Professor Malcolm Lader – Long-term effects
of carbon monoxide on the brain
12. Professor Lader outlined the subtle impairments
of neuropsychiatric function found in cases with chronic low-level exposure
to carbon monoxide. These included impairment of short-term memory (particularly
auditory), problems with sequential tasks, reductions in IQ and visuo-spatial
abilities, effects on creativity and word recall, irritability and low-grade
depression. The Committee agreed these effects could be a consequence
of high-level exposure to CO but considered that the occurrence of these
effects at low levels was much less clear as often all that was known
was that an appliance had been defective.
Generalised additive models
- Professor Anderson reported that the potential problems with generalised
additive models were still not fully resolved but it was considered
that (i) generalised additive models gave slightly higher results than
generalised linear models (ii) NMMAPS found greater errors than other
research groups (iii) there was still evidence for significant positive
associations of pollutants with mortality and hospital admissions.
7th Annual Air Pollution and Research Review Meeting
at IEH
- Members were encouraged to attend this meeting on 1st and
2nd April 2003.
Killer Smogs of 1950s London – Talk by Professor Roy Richards
- Professor Roy Richards gave a talk on applying modern analytical methods
to stored samples of 1950s particles. Concentrations were very high
(up to 7 mg/m3) in the 1950s and the filters were covered
mostly with soot (100-700nm) and respirable smelter particles. The particles
were less potent than modern particles in a simple in vitro oxidative
assay. Pilot studies to consider the relative potency of the different
types of particles on gene expression in the heart in vivo were
just starting.
15. 21st February 2003 in Skipton House.
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