TABLE 1.
Baseline Characteristics of the LIFEWORK Participants and Estimated Annual Pollutant Exposuresa at Subject Recruitment, Overall and by Levels of Pollution Exposureb
| Low Exposure | Moderate Exposure | High Exposure | Overall | |
|---|---|---|---|---|
| (N=34,018) | (N=37,853) | (N=15,011) | (N=86,882) | |
| No. of participants (%) | ||||
| Amigo | 22 | 15 | 10 | 17 |
| EPIC | 9 | 16 | 28 | 15 |
| Nightingale | 69 | 69 | 62 | 68 |
| Age (years) | ||||
| Mean (SD) | 48.8 (11.6) | 50.5 (12.9) | 52.2 (14.3) | 50.2 (12.7) |
| Sex (%) | ||||
| Male | 12 | 9 | 9 | 11 |
| Female | 88 | 91 | 91 | 89 |
| Highest level of education attainedc (%) | ||||
| Low | 11 | 14 | 18 | 14 |
| Intermediate | 48 | 43 | 35 | 44 |
| High | 41 | 43 | 47 | 42 |
| Missing | 0.2 | 0.2 | 0.3 | 0.2 |
| Smoking status (%) | ||||
| Never | 48 | 47 | 44 | 46 |
| Former | 40 | 40 | 40 | 40 |
| Current | 11 | 12 | 14 | 13 |
| Missing | 0.6 | 1.0 | 1.7 | 1.0 |
| Body mass index (kg/m2) | ||||
| Mean (SD) | 25.2 (4.16) | 25.3 (4.30) | 25.2 (4.41) | 25.3 (4.26) |
| Missing (%) | 0.4 | 0.6 | 0.9 | 0.6 |
| CVD diagnosis at baseline (%) | ||||
| Negative | 93 | 93 | 90 | 92 |
| Positive | 7 | 7 | 10 | 8 |
| COPD diagnosis at baseline (%) | ||||
| Negative | 98 | 97 | 96 | 97 |
| Positive | 2 | 3 | 4 | 3 |
| Cancer diagnosis at baseline (%) | ||||
| Negative | 98 | 97 | 95 | 97 |
| Positive | 2 | 3 | 5 | 3 |
| Monthly income estimated | ||||
| Mean (SD) | 2,590 (764) | 2,800 (890) | 2,870 (1,000) | 2,730 (873) |
| Missing (%) | 5.1 | 3.4 | 3.3 | 4.0 |
| Normalized difference vegetation index | ||||
| Mean (SD) | 0.571 (0.0844) | 0.503 (0.0796) | 0.448 (0.0864) | 0.520 (0.0943) |
| Missing (%) | 2.6 | 1.2 | 0.9 | 1.7 |
| NO2 (μg/m3) | ||||
| Mean (SD) | 17.7 (2.55) | 24.9 (2.25) | 33.7 (4.30) | 23.6 (6.34) |
| PM2.5 (μg/m3) | ||||
| Mean (SD) | 16.3 (0.721) | 16.7 (0.559) | 17.0 (0.707) | 16.6 (0.704) |
| PM2.5 absorbance (10−5 m−1) | ||||
| Mean (SD) | 1.09 (0.132) | 1.29 (0.125) | 1.57 (0.227) | 1.26 (0.225) |
| PM10 (μg/m3) | ||||
| Mean (SD) | 24.1 (0.381) | 24.7 (0.643) | 26.4 (1.42) | 24.8 (1.12) |
| Oxidative potential (nmol DTT/min/m3) | ||||
| Mean (SD) | 1.06 (0.208) | 1.22 (0.165) | 1.32 (0.119) | 1.17 (0.202) |
Air pollution levels were estimated at baseline based on annual average concentrations measured between October 2008 and April 2011 (NO2, PM2.5, PM2.5 absorbance, PM10) and between February 2009 and February 2010 (Oxidative Potential).
Low, medium, and high levels of exposures derived with cluster analysis.
Low: primary school, lower vocational training or lower secondary education; intermediate: intermediate vocational education or intermediate/higher secondary education; high: higher vocational education or university degree.
Household income was estimated based on participants’ baseline postal code. Each postal code was linked to income data from Statistics Netherlands for December 2012.
CVD, cardiovascular disease; COPD, chronic obstructive pulmonary disease; SD, standard deviation.