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Table 1 Characteristics of participants

From: Relationships between perceived health status and ambient air quality parameters in healthy Japanese: a panel study

  February May July
  Kumamoto Niigata Kumamoto Niigata Kumamoto Niigata
N 1537 1350 1101 1119 905 987
  100% 100% 71.6% v. Feb 82.9% v. Feb 58.9% v. Feb 73.1% v. Feb
Year of survey N   N   N v. Feb N v. Feb N v. Feb N v. Feb
 2010 186 12.1% 121 65.1% 104 55.9%
 2011 212 13.8% 198 14.7% 159 75.0% 152 76.8% 140 66.0% 132 66.7%
 2012 306 19.9% 299 22.1% 234 76.5% 225 75.3% 196 64.1% 192 64.2%
 2013 287 18.7% 243 18.0% 197 68.6% 212 87.2% 163 56.8% 191 78.6%
 2014 274 17.8% 305 22.6% 202 73.7% 266 87.2% 155 56.6% 230 75.4%
 2015 272 17.7% 305 22.6% 188 69.1% 264 86.6% 147 54.0% 242 79.3%
Age
 years old (mean ± SD) 64.4 ± 9.8 59.1 ± 6.2 65.9 ± 9.5 59.5 ± 6.1 66.7 ± 9.5 59.7 ± 6.1
Gender N   N   N   N   N   N  
 Male 1089 70.9% 939 69.6% 798 72.5% 771 68.9% 663 73.3% 674 68.3%
 Female 448 29.2% 411 30.4% 303 27.5% 348 31.1% 242 26.7% 313 31.7%
Body mass index
 kg/m2 (mean ± SD) 23.6 ± 3.1 23.2 ± 3.1 23.4 ± 2.9 23.1 ± 3.0 23.3 ± 2.9 23.0 ± 3.0
Smoking status N   N   N   N   N   N  
 Current smoker 210 13.7% 312 23.1% 121 11.0% 232 20.7% 89 9.8% 192 19.5%
 Former smoker 561 36.5% 481 35.6% 430 39.1% 422 37.7% 364 40.2% 367 37.2%
 Never smoker 766 49.8% 557 41.3% 550 50.0% 465 41.6% 452 49.9% 428 43.4%
Working status N   N   N   N   N   N  
 Active worker 951 63.6% 1169 86.9% 608 56.1% 939 84.1% 463 52.0% 820 83.3%
 Retired/ Not in employment 544 36.4% 177 13.2% 476 43.9% 178 15.9% 428 48.0% 165 16.8%
Time spent outdoors
 Hours 4.0 ± 3.2 4.7 ± 4.2 4.2 ± 3.2 4.1 ± 3.6 4.0 ± 3.1 3.9 ± 3.4
Prevalence of respiratory symptoms
 1. Weather affects cough 88 5.8% 86 6.4% 76 7.1% 66 6.0% 37 4.2% 59 6.1%
 2. Sputum production without a cold 391 25.5% 397 29.5% 303 28.4% 320 28.9% 222 25.0% 253 26.0%
 3. Sputum production in early morning 258 16.9% 213 15.8% 193 18.1% 172 15.6% 142 16.0% 160 16.6%
 4. Frequent wheezes 123 8.0% 108 8.0% 89 8.3% 91 8.3% 54 6.1% 70 7.2%
 5. Allergy 307 20.0% 232 17.3% 239 22.1% 239 21.6% 145 16.3% 164 16.9%
Monitoring station
 Number of stations 26 23         
Distance from each residence
 Median (Min. – Max.) (km) 3.70 (0.06–33.43) 3.31 (0.10–30.88)