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#####  FEV1, Asthma, and Air Pollution        #####
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VARIABLES:

ID                -- subject ID variable
MALE              -- gender (0=female, 1=male)
CASE              -- asthmatic status (0=non-asthmatic, 1=asthmatic case)
GRADE             -- recruitment cohort (0=4th grade, 1=7th grade)
RACE              -- subject race (0=white, 1=non-white)
ANNUAL OZONE      -- annual average exposure to ozone (ppb)
ANNUAL NO2        -- annual average exposure to NO2
FEV1              -- forced expiratory volume (pulmonary function measure)
AGE               -- age (years) at visit
HEIGHT            -- height (cm) at visit
BMI               -- body mass index (weight kg / height^2 m^2)
SECOND SMOKE      -- exposured to second-hand smoke
ASTHMA SYMPTOM    -- asthma symptoms at visit (0=no, 1=yes)
RESP INFECTION    -- respiratory infection at visit (0=no, 1=yes)
MONTH OZONE       -- mean level of ozone for the month
MONTH NO2         -- mean level of NO2 for the month
DAY OZONE         -- daily measure of ozone
NO2 DAY           -- daily measure of NO2