Heart Attacks in Cold Cities

English: Pneumonia and influenza mortality for...

English: Pneumonia and influenza mortality for 122 US cities, 4 years through week ending October 31, 2009. This time series shows the seasonality of seasonal influenza, and that during the 2007-2008 season influenza exceeded the US epidemic threshold. (Photo credit: Wikipedia)

Influenza epidemics, seasonality, and the effects of cold weather on cardiac mortality(20 page pdf, Stephanie von Klot, Antonella Zanobetti and Joel Schwartz,  Environmental Health, Oct.1, 2012)

Today we review a study of a large sample of seniors in 78 cities across the USA to assess what impact cold weather has on heart attacks and how much influence influenza epidemics  has on the mortality rate – in the absence, unfortunately, of corresponding air pollution data which is known to have health impacts. Results indicate that there is a link between variations in mortality rates with the influenza. While these results are interesting, a similar study in colder countries with many more sub-zero winter days, such as Russia or Canada, along with associated air pollution data would be revealing.

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2 Responses

  1. Numerous time series studies have indicated a positive association between short-term variation in ambient levels of particulate matter and daily mortality counts ( 1 – 3 ). The models used in these studies have typically assumed that the association between particulate matter and daily mortality is constant over the study interval. However, the short-term effects of particulate matter on mortality might plausibly exhibit seasonal variation. Studies in a number of locations have shown that the characteristics of the particulate matter mixture change throughout the year and that the relative and absolute contributions of particular components to particulate matter mass may be different during different times of the year (see chapter 3 of Air Quality Criteria for Particulate Matter ( 4 )). Patterns of human activity also change from season to season, so that a particular air pollution concentration in one season may lead to a different exposure in another season. Other potential time-varying confounding and modifying factors, such as temperature and influenza epidemics, can also affect estimates of short-term effects of air pollution on mortality differently in different seasons. All of the issues described above indicate a need to extend current models for time series data on air pollution and health to incorporate time-varying pollution effects.

    • All good points. That said the recognition of the impacts of short term pollutants on health by environmental health specialists does not seem to be accepted by those who monitor air pollution especially near roads and traffic and especially in cities in the US and Canada.

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