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Table 1 Characteristics of PM 2.5 measurements and days exceeding the standards by the SEPA, EPA, and the WHO from 2008 to 2013

From: PM2.5 in Beijing – temporal pattern and its association with influenza

Year

Measurements (days)

Range (lowest, highest)

Annual mean

Days1(%)

Days2(%)

Days3(%)

2008

212

(5.8 235.38)

84.74 (50.31)

105 (49.53)

174 (82.08)

194 (91.51)

2009

263

(13.94, 482.25)

104.65(70.41)

165 (62.74)

227 (86.31)

239 (90.87)

2010

320

(9.0, 441.5)

104.89 (76.38)

186 (58.13)

267 (83.44)

286 (89.38)

2011

333

(10.38, 492.75)

98.30 (79.65)

170 (51.05)

257 (77.18)

279 (83.78)

2012

329

(2.92, 428.54)

91.74 (68.85)

169 (51.37)

246 (74.77)

278 (84.50)

2013

289

(10.5, 568.57)

103.04 (83.77)

149 (51.56)

242 (83.74)

262 (90.66)

  1. Days1 – days with 24-hr average exceeding the SEPA standard; days2 – days with 24-hr average exceeding the EPA standard; days3 – days with 24-hr average exceeding the WHO standard.