The risk in Iraq is that despite good intentions, we'll become irritated and distracted and leave the job half-done, as we did after the first gulf war and after Afghanistan, when we refused to provide security outside Kabul.

CNN: Nicholas Kristof: Running for the exits

These reactions cause the airways to become narrower and irritated, which leads to the symptoms of asthma - such as wheezing, shortness of breath and a tight chest.

BBC: NEWS | Health | Overweight 'higher asthma risk'