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Daily Mean Temperature and Adult Asthma in Shanghai, China

Paper Reviewed
Zhang, Y., Peng, L., Kan, H., Xu, J., Chen, R., Liu, Y. and Wang, W. 2014. Effects of meteorological factors on daily hospital admissions for asthma in adults: A time-series analysis. PLOS ONE 9: e102475.

In a paper published in the Open-Access journal PLOS ONE, Zhang et al. (2014) write that "there is limited evidence for the impacts of meteorological changes on asthma hospital admissions in adults." And, therefore, they set about to quantitatively evaluate the short-term effects of daily mean temperature on adult asthma hospital admissions in Shanghai, China. This they did for the period of time between January 2005 and December 2012, "after controlling for secular and seasonal trends, weather, air pollution and other confounding factors," following which "a Poisson generalized additive model combined with a distributed lag non-linear model were used to explore the associations between temperature and hospital admissions for asthma." And what did they thereby discover?

The seven scientists say that during the study period, there were 15,678 hospital admissions for adult asthma by residents of Shanghai, which worked out to an average of 5.6 per day. And they indicate there was a significant negative correlation between asthma hospitalizations and daily mean temperature (DMT), "with lower temperatures associated with a higher risk of hospital admission for asthma," wherein "the cold effect appeared to be relatively acute, with duration lasting several weeks, while the hot effect was short-term." In fact, they say they actually found that "warmer temperatures were not associated with asthma hospital admissions."

Ultimately concluding that their findings suggest that "cold temperature may trigger asthma attacks," Zhang et al. say that "effective strategies are needed to protect populations at risk from the effects of cold." And we would merely note, in this regard, that that's what a little bit of global warming does - essentially everywhere and all of the time - for it does it primarily by increasing daily minimum temperatures three times more than it increases daily maximum temperatures, as has been demonstrated to be the case by Karl et al. (1984, 1991). And thus it can be appreciated that global warming, if it ever "kicks in" again, can be said to be "working overtime" to boost the most dangerous temperature of each individual day as it pertains to the risk of asthma attacks.

References
Karl, T.R., Jones, P.D., Knight, R.W., Kukla, G., Plummer, N., Razuvayev, V., Gallo, K.P., Lindseay, J., Charlson, R.J. and Peterson, T.C. 1984. A new perspective on recent global warming: asymmetric trends of daily maximum and minimum temperature. Bulletin of the American Meteorological Society 74: 1007-1023.

Karl, T.R., Kukla, G., Razuvayev, V.N., Changery, M.J., Quayle, R.G., Heim Jr., R.R., Easterling, D.R. and Fu, C.B. 1991. Global warming: evidence for asymmetric diurnal temperature change. Geophysical Research Letters 18: 2253-2256.

Posted 1 December 2014