The peak flow meter is a device for monitoring one's breathing capacity; a diminishing capacity is a warning sign of a possible attack. When the attack comes, one must avoid panic and breathe as deeply and as slowly as possible. But during an attack suicide would be an impossibility, because the compulsion to breathe is irresistible. Asthma is not all attack, it is a chronic condition, depending on its severity, of wheezing, the production of clotted sputum, tightness in the chest, postnasal drip, skin rashes; it is life-threatening; it can lead to suffocation if not treated. In some sufferers attacks are infrequent and the chronic condition is in abeyance, so for most of their lives they are asymptomatic. Asthma attacks are triggered by allergies to dust, to plants, to foods; by changes in weather, by stress-the possibilities are endless. The allergist tests for them by pricking the skin of one's back and arms a hundred times for reactions.