Lung disease encompasses both chronic obstructive pulmonary disease (COPD) and asthma. COPD is one of the largest categories of lung disease, affecting over 15 million Americans, and is the fourth leading cause of death in the US. COPD is a term for two closely related diseases of the respiratory system, chronic bronchitis, which afflicts 14.1 million individuals, and emphysema, which afflicts 2 million. Almost one million people have both conditions. Asthma is another chronic lung disease and is characterized by inflammation of the air passages. The prevalence of asthma has been increasing since the early 1980s, now affecting an estimated 17 million Americans. The prevalence of the disease is particularly strong amongst children, with 5 million of the existing cases affecting those under the age of 18. In 1998, $11.3 billion was spent on managing asthma in the US. The Sensatex System's sensory capabilities will permit effective monitoring of these debilitating conditions.