Short note of Meeting- 23 June 2006

Membership changes

1. Professor David Phillips had replaced Professor Peter Blain as Chairman of the COC and would therefore be replacing Professor Blain as an ex officio member of COMEAP.

Matters arising

2. The Committee's report on Air Pollution and Cardiovascular Disease was published at the end of March and had been well received.

3. It was not going to be possible to organise the Annual Air Pollution Research Meeting this year but it was aimed to hold the next one in April next year. It was agreed that the dates of the Spring HEI meeting would be checked to avoid a clash.

QUARK2 - Update

4. COMEAP's Sub-Group on the Quantification of the Health Effects of Air Pollution in the UK (QUARK2) had met on 23rd May to consider the draft report on the effects of long-term exposure to air pollution on mortality. It had been decided to publish this separately and not to wait for the consideration of the effects of long-term exposure to air pollution on morbidity.

5. The interim statement published in January had noted that the sub-group wished to consider uncertainty further. An uncertainty elicitation exercise had been undertaken. The group suggested an uncertainty range of 2 to 9% around the recommended coefficient of 6% per 10 µg/m3 PM2.5.

6. The sub-group had suggested some restructuring of the report. Although the Secretariat was well advanced with this, there was insufficient time to bring the report to the June meeting of COMEAP. The report would come to the full Committee in October.

7. QUARK2 would be moving on to discussing the effect of long-term exposure to air pollution on morbidity. A strategy meeting to propose how to approach this issue was going to be held on 11th July with the Chairmen of COMEAP, QUARK2 and the morbidity working group.

Buncefield fire

The Committee next discussed the impact of the large fire at the Buncefield oil depot on 11th December 2005. A presentation was given by Professor Virginia Murray from the Health Protection Agency. The Committee was provided with a detailed report from netcen on the air pollution levels at the time of the fire(1) . Due to the fact that the plume remained above the boundary layer, monitored air pollution levels did not, in general, rise above normal levels. The Committee considered, therefore, that it was unlikely that there would have been any significant increase in health effects due to air pollution from the fire. A statement on the Committee's views is in preparation.

(1) http://www.defra.gov.uk/environment/airquality/buncefield/index.htm

Ozone

8. A chapter from the ozone report on long-term exposure to ozone was discussed. The following conclusions were reached:

• It was concluded, overall, that there was insufficient evidence for an association between long-term exposure to ozone and mortality. It was noted that the strongest evidence on admissions was for respiratory admissions in the elderly rather than for cardiovascular admissions. Respiratory mortality tends to occur later than cardiovascular mortality leading to a smaller loss of life expectancy. This might explain why the association between short-term exposure to ozone and mortality is not clearly picked up in the long-term exposure studies.
• It was concluded that the evidence on ozone and lung cancer was inconsistent but pointed in the direction of no effect.
• The evidence on long-term exposure to ozone and respiratory symptoms was mixed. The majority of studies found positive associations with at least one respiratory symptom but there was less consistency across studies for individual symptoms.
• The evidence predominantly indicated that children living in, and tested in, a high ozone area tended to have lower lung function.
• Associations between long-term exposure to ozone and lung function growth were found in some studies not others. This effect may be reversible with age or over a winter period. The evidence on lung function growth was perhaps less clear cut than might have been expected from the strong evidence on short-term exposure to ozone and lung function
  

9. The Executive Summary for the report was also discussed. The Committee agreed with the proposal to include a summary of meta-analysis results in the Executive Summary but to make clear that the conclusions drew also on other evidence (some studies did not meet the strict criteria for inclusion in the meta-analysis but, for example, used a closely related set of ICD codes). Some further minor changes to the Executive Summary were suggested.

10. The key conclusions from the report had now all been decided. However, there was still substantial editing and formatting work to do on the report before it would be published for comment on the website later this year.

Changes to PM10 and PM2.5 monitoring methods - implications for epidemiological studies

11. It was explained that the standard monitoring device(2) in DEFRA's network misses some particle mass due to loss of volatiles from the heated filters. A correction factor of 1.3 had previously been used to compensate for this. DEFRA had now published the results of a detailed study that investigated the robustness of this factor using criteria set by the European Commission (3). It was found that the current equipment did not meet these equivalence criteria even with a correction factor. DEFRA will therefore be retrofitting their monitoring equipment to correct for the loss of semi-volatile particles (4).

(2)The TEOM (Tapered Element Oscillating Microbalance )
(3)www.airquality.co.uk/archive/reports/cat05/0606130952_UKPMEquivalence.pdf
(4)The new equipment is known as TEOM retrofitted with FDMS. FDMS stands for Filter Dynamics Measurement System.

12. The Secretariat was keen to publicise this change to the particle monitoring methods as it clearly has implications for epidemiological studies. However, the report does include equations that allow conversion of data from the old equipment to data equivalent to that from the new equipment and vice versa - this should help in ensuring consistency between epidemiological studies from different periods. The air quality archive would, in future, report the new total results as the main result but would also give the base data and the volatiles data separately. The Committee considered that the latter might be interesting for epidemiological studies in its own right. The Committee also considered that it would be helpful, where possible to if any changes to the equipment could take place close to the beginning of a year.

Date of next meeting

13. The next meeting is due to be held on 13th October 2006.

Secretariat
July 2006

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