Table 2. Studies of prevalence of chronic obstructive pulmonary disease in India without quality concerns Reviewed studies of prevalence of chronic bronchitis (CB) and/or chronic obstructive pulmonary disease (COPD) in India. All were cross-sectional studies. Population characteristics and smoke/pollution exposure data are entered as available. The numbers following the different quality options (G, P, N) indicate the number of quality assessment points (see Box 1) rated as such.