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Table 4 Bivariate analysis of factors associated with the presence/absence of acne according to the dermatologist’s diagnosis

From: Association between exposure to ambient air pollution and occurrence of inflammatory acne in the adult population

Variable Absence of acne
(N = 248)
Presence of acne
(N = 124)
p
Gender 0.003
 Male 94 (77.0%) 28 (23.0%)  
 Female 154 (61.6%) 96 (38.4%)  
Skin type < 0.001
 Normal 77 (87.5%) 11 (12.5%)  
 Dry 19 (76.0%) 6 (24.0%)  
 Mixed 85 (61.2%) 54 (38.8%)  
 Oily 48 (53.3%) 42 (46.7%)  
Use of hydrating cream 0.001
 No 84 (79.2%) 22 (20.8%)  
 Yes 164 (61.7%) 102 (38.3%)  
Number of times you wash your face per week 0.207
 Never 156 (63.2%) 91 (36.8%)  
 1–2 times 35 (74.5%) 12 (25.5%)  
 3–5 times 35 (76.1%) 11 (23.9%)  
 Daily 22 (68.8%) 10 (31.3%)  
Use of medical devices 0.596
 No 226 (66.3%) 115 (33.7%)  
 Yes 22 (71.0%) 9 (29.0%)  
Use of cream powder 0.149
 No 180 (69.0%) 81 (31.0%)  
 Yes 68 (61.3%) 43 (38.7%)  
Stress/sleep deprivation 0.047
 No 141 (71.2%) 57 (28.8%)  
 Yes 107 (61.5%) 67 (38.5%)  
Intake of sugar-based products 0.354
 1–2 times per week or less 76 (62.8%) 45 (37.2%)  
 3–5 times per week 96 (71.1%) 39 (28.9%)  
 Every day 76 (65.5%) 40 (34.5%)  
Whey proteins intake 0.548
 1–2 times per week or less 227 (66.2%) 116 (33.8%)  
 3–5 times per week 15 (68.2%) 7 (31.8%)  
 Every day 6 (85.7%) 1 (14.3%)  
Dairy products intake 0.561
 1–2 times per week or less 39 (60.9%) 25 (39.1%)  
 3–5 times per week 107 (68.2%) 50 (31.8%)  
 Every day 102 (67.5%) 49 (32.5%)  
Carbohydrates intake 0.258
 1–2 times per week or less 98 (63.6%) 56 (36.4%)  
 3–5 times per week 110 (71.4%) 44 (28.6%)  
 Every day 40 (62.5%) 24 (37.5%)  
Hours in front of screen 0.683
 0–1 h 5 (62.5%) 3 (37.5%)  
 2–3 h 67 (70.5%) 28 (29.5%)  
 4–5 h 84 (63.2%) 49 (36.8%)  
 6 h or more 92 (67.6%) 44 (32.4%)  
Smoking 0.139
 No 159 (64.1%) 89 (35.9%)  
 Yes 89 (71.8%) 35 (28.2%)  
Passive smoking daily 0.161
 No 143 (69.8%) 62 (30.2%)  
 Yes 105 (62.9%) 62 (37.1%)  
Living close to a highway/busy road 0.116
 No 162 (64.0%) 91 (36.0%)  
 Yes 86 (72.3%) 33 (27.7%)  
Living close to an electric generator 0.933
 No 185 (66.5%) 93 (33.5%)  
 Yes 63 (67.0%) 31 (33.0%)  
Living near a power plant 0.728
 No 219 (66.4%) 111 (33.6%)  
 Yes 29 (69.0%) 13 (31.0%)  
Working near a power plant 0.179
 No 235 (67.5%) 113 (32.5%)  
 Yes 13 (54.2%) 11 (45.8%)  
Driving a car 0.650
 No 28 (63.6%) 16 (36.4%)  
 Yes 220 (67.1%) 108 (32.9%)  
Using the air condition in the car 0.745
 No 14 (70.0%) 6 (30.0%)  
 Yes 234 (66.5%) 118 (33.5%)  
Hours stuck in traffic per day 0.266
 Not applicable 61 (71.8%) 24 (28.2%)  
 1–2 h per day 159 (65.4%) 84 (34.6%)  
 3–4 h per day 24 (60.0%) 16 (40.0%)  
 5 or more hours per day 4 (100.0%) 0 (0%)  
Hours of outdoor activities per day 0.142
 Not applicable 62 (68.1%) 29 (31.9%)  
 1–2 h per day 140 (69.0%) 63 (31.0%)  
 3–4 h per day 43 (62.3%) 26 (37.7%)  
 5 or more hours per day 3 (33.3%) 6 (66.7%)  
Exposure to NO2 categories 0.079
 None 26 (74.3%) 9 (25.7%)  
 Mild 65 (57.5%) 48 (42.5%)  
 Moderate 128 (71.1%) 52 (28.9%)  
 Severe 29 (65.9%) 15 (34.1%)  
Exposure to CO categories 0.638
 None 235 (66.4%) 119 (33.6%)  
 Mild 12 (75.0%) 4 (25.0%)  
 Moderate 1 (50.0%) 1 (50.0%)  
Exposure to SO2 categories 0.735
 None 180 (65.9%) 93 (34.1%)  
 Mild 53 (70.7%) 22 (29.3%)  
 Moderate 14 (63.6%) 8 (36.4%)  
 Severe 1 (50.0%) 1 (50.0%)  
Exposure to O3 categories 0.355
 None 220 (67.1%) 108 (32.9%)  
 Mild 28 (65.1%) 15 (34.9%)  
 Moderate 0 (0%) 1 (100.0%)  
Exposure to PM10 categories 0.144
 None 72 (59.5%) 49 (40.5%)  
 Mild 90 (69.8%) 39 (30.2%)  
 Moderate 72 (68.6%) 33 (31.4%)  
 Severe 14 (82.4%) 3 (17.6%)  
Exposure to PM2.5 categories 0.182
 None 2 (50.0%) 2 (50.0%)  
 Mild 51 (58.0%) 37 (42.0%)  
 Moderate 150 (70.4%) 63 (29.6%)  
 Severe 45 (67.2%) 22 (32.8%)  
Age (in years) 31.10 ± 13.89 26.13 ± 9.14 < 0.001
Body Mass Index 23.99 ± 4.70 21.99 ± 3.99 < 0.001
Household crowding index 0.94 ± 0.44 0.90 ± 0.44 0.426
Number of family members with acne or history of acne 0.61 ± 0.71 0.97 ± 0.82 < 0.001
Times you wash your face per week
  1. Numbers in bold indicate significant p-values.