2. A significant increase in number of persons with FEV below appear to be less important. It should be emphasized that a small, but statistically significant, reduction in a population mean FEV, or FEV_0.75, is probably medically significant, because such a difference may indicate an increase in the number of persons with respiratory impairment in the population. In other words, a small part of the population may manifest a marked change that is medically significant to them, but when averaged with the rest of the population, the change appears to be small.

3. An increased rate of decline in pulmonary function (FEV₁) relative to predicted value in adults with increasing age or failure of children to maintain their predicted FEV₁ growth curve. Such data must be standardized for sex, race, height, and other demographic and anthropometric factors.

7. Increased prevalence of wheezing in the chest apart from colds, or of wheezing most days or nights. (The significance of wheezing with colds needs more study and evaluation.)

8. Increased prevalence or incidence of chest tightness.

9. Increased prevalence or incidence of cough/phlegm production requiring medical attention.

10. Increased incidence of acute upper respiratory tract infections that interfere with normal activity.

11. Acute upper respiratory tract infections that do not interfere with normal activity.

12. Eye, nose, and throat irritation that might interfere with normal activity (i.e., driving a car) if severe.

ATS (American Thoracic Society), Scientific Assembly for Environmental and Occupational Health. 1985. Guidelines as to what constitutes an adverse respiratory health effect, with special reference to epidemiologic studies of air pollution. Am. Rev. Respir. Dis. 131:666-668.