But the body of the text proves rather more cautious
"By contrast with directly countable events, which can be listed in national health statistics (eg, deaths or injuries due to traffic accidents), it is not possible to directly identify the victims of complex substances and mixtures with cumulative toxicity, such as smoking or air pollutants. Neither are the health-relevant characteristics of the exposure unanimously defined, nor are the health outcomes specifically linked to air pollution only. Therefore, uncertainty remains an inherent characteristic of any attempt to derive attributable cases."
Indeed if we were to directly correlate vehicle registration with deaths from bronchitis in the UK we would be left with the conclusion that car exhaust reduces risks:
Per 100 000 of population
1993 1994 1995 1996 1997 1998 Female deaths from bronchitis: 43.1 39.6 43.0 43.0 44.0 43.3 Male deaths 68.9 60.6 63.4 60.0 60.0 57.8
vehicle registration, thousands:
1988 18,888
1997 22,832
1998 23,293
The idea that air quality has declined is especially hard to fathom bearing in mind the impact of the London smogs. On the week beginning 5th December 1952, four thousand Londoners died in smog.
-- James Heartfield
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