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Maternal
mortality

Summary
tables
* For the third year running none of the deaths in pregnancy or childbirth was due to sepsis ; ten of the 19 post-abortion
deaths came under the category of' abortion with sepsis
Tables summarising the more important of these vital statistics (a) by metropolitan
boroughs and (b) showing the secular trend for the County are to be found on pages 21
and 22.
Atmospheric pollution
In my last two annual reports I have given, in some detail, evidence in support of the
hypothesis that when the level of atmospheric pollution reaches about four times the
winter average* an 'excess' of deaths of the order of 3-400 may be expected.
Fortunately in 1958 at no time did pollution reach this apparently critical level but
the month of November was marked by persistent fog—fog was mentioned in the
meteorological reports of Kew Observatory on 20 days in the month. It was therefore
felt advisable to examine the pollution and mortality figures for November in some
detail in order to ascertain how the effect, if any, of a fairly persistent pollution below
the critical level compared with that of a relatively short period of pollution above it.
Figure 4 (p. 17) shows the daily mean concentrations for each day of November—days
upon which fog was mentioned are indicated : the highest and lowest daily temperatures
recorded at Kew Observatory over the same period are also shown.
The figure shows clearly the fluctuations that occur from day-to-day in the level
of pollution and also that the six consecutive days of fog, including the highest level of
pollution, corresponded broadly with the days of lowest temperature.
The figure also shows the seven-day moving average of deaths occurring in London,
for all deaths and for deaths affecting those aged under 70 years of age and 70 years and
over. The daily level of mortality fluctuates in the same way as does that of pollution
and the production of a moving average is therefore a prerequisite to the estimation of
the trend of mortality. Even with this aid the determination of the trend is an extremely
hazardous undertaking in a period when mortality is climbing to its seasonal winter
level; the estimated trend line for all deaths has been shown by the dotted line. It will be
noticed that there were two 'peaks' above the trend line, the first coinciding with the
foggy days from the 4th—7th day, and the second with the period of intermittent fog
from the 12th—17th. It is doubtful whether the first peak was in any way a consequence of
* I.e., a mean daily concentration of 200 milligrams of black suspended matter ('Smoke') per 100 cubic metres of air
and 40 parts of acidic gases (SO2) per 100 million parts of air.
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