How will global warming affect human health?

Jun 28 2007

Global warming will cause more deaths in summer because of higher temperatures but these will not be offset by fewer deaths in milder winters finds an analysis published online ahead of print in Occupational and Environment Medicine.

The Harvard researchers analysed city-specific weather data related to the deaths of more than 6.5 million people in 50 US cities between 1989 and 2000.

They found that during two-day cold snaps there was a 1.59% increase in deaths because of the extreme temperatures. However, during similar periods of extremely hot weather death rates went up by 5.74%. Deaths did not rise as steeply when temperature fluctuations were less extreme.

Deaths from all causes are known to rise when temperatures go up, and heart attacks and cardiac arrests are more likely when it is very cold. It was anticipated that global warming would increase deaths during hot temperatures but that this would be compensated for by fewer deaths in the winter.

But the authors conclude: ‘Our findings suggest that decreases in cold weather as a result of global warming are unlikely to result in decreases in cold-related mortality in the US. Heat-related mortality, in contrast, may increase, particularly if global warming is associated with increased variance of summer temperature.'

While all 50 US cities showed similar rises in deaths when temperatures plummeted, more deaths were seen during extreme temperature rises in cities with milder summers, less air conditioning and higher population density.

The authors suggest that this is because the use of central heating is widespread, whereas fewer people have air-conditioning in their homes.

They say: ‘Central heating, which constitutes an important adaptive mechanism against cold, is almost universal in the US and this may explain why the US population seemed fully acclimatised to cold.

‘Making air conditioning universally available may reduce heat-related mortality but would, on the other hand, have a perverse effect by enhancing global warming through carbon dioxide emissions from electricity consumption.'

Click here to view the paper in full: http://press.psprings.co.uk/oem/june/om33175.pdf

THORAX

Papworth breathing technique cuts asthma symptoms by a third

[Integrated breathing and relaxation training (the Papworth method) for adults with asthma in primary care: a randomised controlled trial; Thorax 2007;0:1–5. doi: 10.1136/thx.2006.076430]

Newswise — A sequence of breathing and relaxation exercises known as the Papworth method has been shown to reduce asthma symptoms by a third by the first randomised controlled trial to investigate the technique, which is published online ahead of print in Thorax .

Eighty five people with mild asthma were randomly assigned to receive either five sessions of treatment by the Papworth method on top of their medical care or to continue to rely on usual drug therapy.

After the sessions had finished, patients' asthma symptoms were assessed using the St George's Respiratory Symptom Questionnaire. Patients who had been treated by the Papworth method scored an average of 21.8 on the questionnaire compared with an average score of 32.8 for patients who had not received the treatment.

And this improvement in symptoms was still maintained one year later. At 12 months patients who had been treated using the Papworth method scored 24.9, while patients who had not scored 33.5.

Use of the Papworth method was associated with less depression and anxiety, and symptoms from inappropriate breathing habits were also reduced. The technique improved the relaxed breathing rate but there was no significant improvement in specific measures of lung function.

The authors say: ‘To our knowledge, this is the first evidence from a controlled trial to demonstrate the effectiveness of the Papworth method.

‘The fact that no significant change was observed in objective measures of lung function suggests that five treatments of the Papworth method do not improve the chronic underlying physiological causes of asthma, but rather their manifestation.'

The Papworth method of physical therapy is a series of integrated breathing and relaxation exercises developed in the 1960s. The breathing training involves a specific diaphragmatic breathing technique, emphasises nose breathing and development of a breathing pattern to suit current activity. It is accompanied by relaxation training and education to help people integrate the exercises into their daily lives and recognise the early signs of stress.