Exposure estimates available in the HELIX entire cohort and subcohort
| Exposure group | Description* | Pregnancy (and specific trimesters)* | Postnatal 0–5 years | Subcohort 6–11 years |
| Outdoor and urban exposure estimates available in the entire cohort and in the subcohort | ||||
| Atmospheric pollutants | NO2, PM2.5, PM10, PM2.5 (absorbance ratio) | √ * | √ | √ |
| Ultraviolet (UV) | Ambient UV radiation levels | √ | √ | √ |
| Surrounding natural space | Average normalised difference vegetation index within buffers of 100, 300 and 500 m Size of and distance to nearest major green or blue space (>5000 m2) Presence of a major green or blue space in a distance of 300 m | √ | √ | √ |
| Meteorology | Land surface temperature average in a buffer of 50 m Temperature from meteorological stations (mean, minimum and maximum) Humidity percentage from meteorological stations Atmospheric pressure data from the ESCAPE project | √ * | √ | √ |
| Built environment | Population density: inhabitants per km2 Building density: built area in m2 per km2 within 100 and 300 m buffers Street connectivity: number of road intersections per km2 within 100 and 300 m buffers Accessibility: metres of bus public transport lines and number of bus public transport stops per km2 within 100, 300 and 500 m buffers Facilities: facility richness index and facility density index in a 300 m buffer Land use evenness index Walkability index in 300 m buffer* | √ | √ | √ |
| Traffic | Total traffic load of major roads in a 100 m buffer, total traffic load in a 100 m buffer, traffic density on nearest road and inverse distance to nearest road | √ | √ | √ |
| Road traffic noise | Day and night time road noise levels | √ | √ | √ |
| Contaminant exposure estimates available in the HELIX subcohort | ||||
| Organochlorine compounds | Blood concentrations of dichlorodiphenyldichloroethylene, dichlorodiphenyltrichloroethane, hexachlorobenzene and polychlorinated biphenyl—118, 68, 153, 170, 180. With and without lipid adjustment. | √ | – | √ |
| Brominated compounds | Blood concentrations of polybrominated diphenyl ether—47, 153. With and without lipid adjustment. | √ | – | √ |
| Perfluorinated alkylated substances | Blood concentrations of perfluorooctanoate, perfluorononanoate, perfluoroundecanoate, perfluorohexane sulfonate, perfluorooctane sulfonate | √ | – | √ |
| Metals and essential elements | Whole blood concentrations of arsenic, cadmium, cesium, cobalt, copper, lead, manganese, mercury, molybdenum, thallium, potassium, magnesium, sodium, selenium and zinc | √ | – | √ |
| Phthalate metabolites | Urine concentrations of monoethyl phthalate, mono-iso-butyl phthalate, mono-n-butyl phthalate, mono benzyl phthalate, mono-2-ethylhexyl phthalate, mono-2-ethyl-5-hydroxyhexyl phthalate, mono-2-ethyl-5-oxohexyl phthalate, mono-2-ethyl 5-carboxypentyl phthalate, mono-4-methyl-7-hydroxyoctyl phthalate, mono-4-methyl-7-oxooctyl phthalate. With and without creatinine adjustment. | √ | – | √ |
| Phenols | Urine concentrations of methyl paraben, ethyl paraben , bisphenol A, propyl paraben, N-butyl paraben, oxybenzone, triclosan. With and without creatinine adjustment. | √ | – | √ |
| Organophosphate pesticide metabolites | Urine concentrations of dimethyl phosphate, dimethyl thiophosphate, dimethyl dithiophosphate, diethyl phosphate, diethyl thiophosphate, diethyl dithiophosphate. With and without creatinine adjustment. | √ | – | √ |
| Tobacco smoking | Urine levels of cotinine. Questionnaire on active and passive smoking. | √ | – | √ |
| Water disinfection by-products | Total concentration of total trihalomethanes (THMs), chloroform and total brominated THMs estimated in tap water from water company concentration and distribution data. | √ | – | – |
| Indoor air | Prediction models for indoor air concentrations of NO2, PM2.5, PMabs, benzene and toluene, ethylbenzene, xylene using panel study data from indoor air samplers. | – | – | √ |
*Walkability indicator adapted from the previous walkability indexes45 46: calculated as the mean of the deciles of population density, street connectivity, facility richness index and land use Shannon’s Evenness Index within 300 m buffers, giving a walkability score ranging from 0 to 1.
ESCAPE, European Study of Cohorts for Air Pollution Effects; HELIX, Human Early Life Exposome; NO2, nitrogen dioxide; PM2.5, mass concentration of particles <2.5 µm in aerodynamical diameter; PM10, mass concentration of particles <10 µm in aerodynamical diameter; PMabs, absorbance of PM2.5 filters; a proxy for elemental carbon, which is the dominant light absorbing substance.