Airborne particulate matter and mitochondrial damage: a cross-sectional study

Table 2 Relative mitochondrial DNA copy number (RMtDNAcn) by subjects' characteristics.

Variable	n	Mean RMtDNAcn*	95% CI*
Age, years
< 39	21	1.14	0.96 to 1.33
39 - 47	21	1.29	1.10 to 1.47
> 47	21	1.14	0.95 to 1.32
Body mass index, kg/m²
≤25	21	1.25	1.07 to 1.44
25 - 27.5	21	1.20	1.10 to 1.38
> 27.5	21	1.12	0.93 to 1.30
Smoking duration, years
0	23	1.17	0.99 to 1.35
0 - 19	19	1.17	0.98 to 1.36
> 19	21	1.23	1.04 to 1.42
Duration of employment, years
< 9	20	1.27	1.08 to 1.46
9 - 21	20	1.17	0.99 to 1.36
> 21	19	1.15	0.96 to 1.34
Education
Primary school	12	1.28	1.07 to 1.48
Middle school	37	1.19	1.01 to 1.36
High school	14	1.12	0.92 to 1.32
Area of residence
Rural	12	1.24	1.05 to 1.42
Suburbs	41	1.14	0.99 to 1.30
City centre	8	1.21	1.00 to 1.41
Self-reported traffic intensity near home
Low	18	1.12	0.94 to 1.29
Medium	38	1.19	1.03 to 1.35
High	5	1.23	1.00 to 1.46

* Based on measurements of DNA from blood samples taken on the first day of a working week (time 1) and after three consecutive days of work (time 2). As each study subject had two measurements of relative mitochondrial DNA copy number (RMtDNAcn), mixed regression models were used to account for within-subject correlation and estimate means and 95% confidence intervals (CI).

ISSN: 1476-069X