A Look Back at the London Smog of 1952 and the Half Century Since

modern field of environmental health owes much to the tragedy that befell Greater London, some 50 years ago this month. From 5 December through 9 December 1952 a heavy, motionless layer of smoky, dusty fumes from the region's million or more coal stoves and local factories settled in the London basin. This thick sulfurous smoky fog, the " smog, " brought traffic and people to a standstill. Not all medical and political authorities appreciated what was happening, but the undertakers and florists knew there was a problem. They ran out of caskets and flowers. Health officials at the time did not appreciate the magnitude or severity of the problem, having previously weathered many dense " pea-souper " fogs and smogs. This fog became known as the Big Smoke because its toll and the public reactions to it were without precedent. Hospital admissions, pneumonia reports, applications for emergency bed service, and mortality followed the peak of air pollution. Mortality remained elevated for a couple of months after the fog. A preliminary report, never to be finalized, attributed these later deaths to an influenza epidemic. New evidence shows that this could not be the case and that only a fraction of the deaths could be from influenza. Davis (2002) leaves 12,000 unexplained and additional deaths during the episode and in the two months after the peak fog ebbed (Bell and Davis 2001). Happily for Londoners, air quality is now much better, with mean annual PM 10 levels (particulate matter ≤ 10 µm in aerodynamic diameter) closer to 30 µg/m 3 than the 300 µg/m 3 50 years ago (and approximately 3,000 µg/m 3 in December 1952). However, risks from air pollution remain. In London, coal stoves are all but gone, but transport is the overwhelming source of PM and NO x emissions. One recent estimate attributed 380 premature fatalities and 350 respiratory hospital admissions per year to emissions from from transport in London (Greater London Authority 2002). In a major collaborative study in Europe overall, Künzli et al. (2000) calculated that the net impact on health from pollution tied with transport was greater than that associated with traffic crashes alone. These tragic public events in London half a century ago spurred the realization that polluted air could not only cause an immediate increase in deaths and illness but could also result in longer-term and more subtle effects. Numerous studies in EHP and …