1. Asthma and Persistent Wheeze in the Harvard Six Cities Study
Frank E. Speizer, M.D., F.C.C.P. 
CHEST 
Volume 98, Issue 5, Pages 191S-195S (November 1990)
DOI: /chest.98.5_Supplement.191S
Copyright © 1990 The American College of Chest Physicians Terms and Conditions

2. Figure 1
Annual levels of sulfur dioxide (SO2), total suspended particulates (TSP), and suspended sulfate (SS), by city, Harvard Six Cities Study.
(Reproduced by permission from ref 5.)
CHEST  , 191S-195SDOI: ( /chest.98.5_Supplement.191S)
Copyright © 1990 The American College of Chest Physicians Terms and Conditions

3. Figure 2 Annual levels of fine particles (<2.5 μm) by city.
CHEST  , 191S-195SDOI: ( /chest.98.5_Supplement.191S)
Copyright © 1990 The American College of Chest Physicians Terms and Conditions

4. Figure 3
Prevalence of bronchitis in the last year stratified by presence or absence of asthma/wheeze, by level of annual respirable particulates (PM15).
(Reproduced by permission from ref 8.)
CHEST  , 191S-195SDOI: ( /chest.98.5_Supplement.191S)
Copyright © 1990 The American College of Chest Physicians Terms and Conditions

5. Figure 4
Level of pulmonary function in children, stratified by presence or absence of asthma/wheeze by level of annual respirable particulates (PM15).
(Reproduced by permission from ref 8.)
CHEST  , 191S-195SDOI: ( /chest.98.5_Supplement.191S)
Copyright © 1990 The American College of Chest Physicians Terms and Conditions

6. Figure 5
Relative odds of reported symptoms in adults by cumulative levels of occupational dust exposure, adjusted for age and smoking.
(Reproduced by permission from ref 9.)
CHEST  , 191S-195SDOI: ( /chest.98.5_Supplement.191S)
Copyright © 1990 The American College of Chest Physicians Terms and Conditions