5=May; 6=June; 7=July; 8=August; 9=September; 10=October; 11=November; 12=December
0=Belgian; 1=EU (plus Switzerland, Norway, UK, Ireland); 2=non-EU
0=only on foot, bicycle, moped, or scooter; 1=only car, bus, tram or train; 2=combination
1=less than 2 hours; 2=2 to 6 hours; 3=more than 6 hours
1=less than 2 hours; 2=2 to 7 hours; 3=more than 7 hours
0=almost never to occasionally; 1=several times a month or weekly; 2=several times a week or daily
1=less than 1x per day; 2=1x per day; 3=more than 1x a day
1=1x per day or less; 2=more than 1x per day
1=1x per week or less; 2=more than 1x per week; 3=daily or more
1=1x per week or less; 2=more than 1x per week
1=less than 1x per day; 2=1x per day or more
0=never; 1=monthly or less; 2=weekly or more
0=never; 1=monthly or less to weekly or more
0=never; 1=1 to 4 times a month; 2=2 to 6 times a week; 3=daily or more
0=no breastfeeding; 1=<1 month; 2=1-6 months; 3=>6 months
1=organic; 2=non-organic (plus-step or foster adoption, other)
0=very to rather difficult; 1=rather easy; 2=easy to very easy
0=never; 1=<1x per week; 2=1-3x per week; 3=4-7x per week
0=never up to <1x a week; 1=1-7x per week
0=never; 1=<1x per week; 2=1-3x per week; 3=4-7x per week; 4=Not applicable
0=never up to <1x a week; 1=1-7x per week; 2=Not applicable
0=no stove or fireplace; 1=closed system (wood pellets, fuel oil, fuel oil, gas stove); 2=open system (wood-burning stove, fireplace or coal stove)
0=no heater; 1=little or sometimes; 2=often or main heating
0=no (never or ever once); 1=yes, less than daily; 2=yes, daily
0=no (never or ever once); 1=yes, <1x per month to daily
0=none (bare feet, socks); 1=slippers; 2=Footwear from the outside
0=never; 1=occasionally (1 to 4 times a month) to daily or more
1=school in study area; 2=school in control area

jaren,  afgerond tot op 2 cijfers na de komma
jaren,  afgerond tot op 2 cijfers na de komma
jaren,  afgerond tot op 2 cijfers na de komma
m
m
jaren, afgerond tot op 1 cijfer na de komma
jaren, afgerond tot op 1 cijfer na de komma
gewogen aantal (1 voor eerste volwassene, 0,5 voor elke tweede en volgende gezinslid ouder dan 14j en 0.3 voor elk gezinslid jonger dan 14j)