Table 1 Characteristics of all fertile men participating in the study and the normal and abnormal semen quality groups
From: Association between ambient particulate matter exposure and semen quality in fertile men
Characteristic | All participants (n = 1554) | Normal semen quality group (n = 1019)a | Abnormal semen quality group (n = 535)b |
|---|---|---|---|
Age (years), n (%) | |||
  < 35 | 1279 (82.3) | 867 (85.1) | 412 (77.0) |
  ≥ 35 | 275 (17.7) | 152 (14.9) | 123 (23.0) |
 Range | 17-52 | 21-50 | 17-52 |
 Mean (SD) | 30.9 (4.2) | 30.7 (4.0) | 31.4 (4.4) |
BMI (kg/m2), n (%) | |||
  < 18.5 | 25 (1.6) | 18 (1.8) | 7 (1.3) |
 18.5 - 24.0 | 643 (41.4) | 420 (41.2) | 223 (41.7) |
 24.0 - 28.0 | 652 (42.0) | 426 (41.8) | 226 (42.2) |
  ≥ 28.0 | 234 (15.0) | 155 (15.2) | 79 (14.8) |
 Mean (SD) | 24.7 (3.3) | 24.7 (3.3) | 24.6 (3.2) |
Ethnicity, n (%) | |||
 Han | 1507 (97.0) | 986 (96.8) | 521 (97.4) |
 Other | 47 (3.0) | 33 (3.2) | 14 (2.6) |
Education, n (%) | |||
 Middle school and below | 19 (1.2) | 10 (1.0) | 9 (1.7) |
 High school and secondary school | 497 (32.0) | 321 (31.5) | 176 (32.9) |
 College degree and above | 1038 (66.8) | 688 (67.5) | 350 (65.4) |
Family income, n (%) | |||
  < 100,000 | 558 (35.9) | 359 (35.2) | 199 (37.3) |
 100,000 - 200,000 | 706 (45.4) | 480 (47.0) | 226 (42.3) |
  ≥ 200,000 | 290 (18.7) | 181 (17.8) | 109 (20.4) |
Smoking status, n (%) | |||
 Never smoker | 968 (62.3) | 629 (61.7) | 339 (63.4) |
 Ever smoker | 586 (37.7) | 390 (38.3) | 196 (36.6) |
 Current smoker | 500 (32.2) | 334 (32.8) | 166 (31.0) |
 Former smoker | 86 (5.5) | 56 (5.5) | 30 (5.6) |
Drinking status, n (%) | |||
 Never drinker | 862 (55.5) | 575 (56.5) | 287 (53.6) |
 Ever drinker | 692 (44.5) | 444 (43.5) | 248 (46.4) |
 Current drinker | 597 (38.4) | 388 (38.0) | 209 (39.1) |
 Former drinker | 95 (6.1) | 56 (5.5) | 39 (7.3) |
Season of sperm collection, n (%) | |||
 Spring | 457 (29.4) | 336 (33.0) | 121 (22.6) |
 Summer | 358 (23.0) | 225 (22.1) | 133 (24.9) |
 Autumn | 371 (23.9) | 225 (22.1) | 146 (27.3) |
 Winter | 368 (23.7) | 233 (22.8) | 135 (25.2) |
Days of abstinence, mean (SD) | |||
  < 3 | 375 (24.1) | 176 (17.3) | 199 (37.2) |
 3 - 5 | 699 (45.0) | 505 (49.5) | 194 (36.3)* |
  ≥ 5 | 480 (30.9) | 338 (33.2) | 142 (26.5)* |
 Mean (SD) | 3.9 (2.6) | 4.1 (2.7) | 3.6 (2.4) |
Semen volume (ml), mean (SD) | 2.7 (1.3) | 2.9 (1.2) | 2.3 (1.5)* |
Sperm concentration (106/ml)c | 58.3 (37.1-84.4) | 63.6 (43.0-87.7) | 47.5 (25.6-76.6)* |
Total sperm number (106)c | 142.9 (79.8-231.8) | 168.0 (111.9-248.6) | 81.9 (34.2-169.6)* |
Total motility (%)c | 56.3 (42.0-69.2) | 61.8 (52.2-73.2) | 36.0 (26.6-52.6)* |