AIR POLLUTION – MONITORING MODELLING AND HEALTH

More documents

Recommendations

Info

376 Air Pollution <strong>–</strong> Monitoring, Modelling and Health Indeed, several studies have shown that short-term (hours to days) exposures to PM significantly enhance cardiovascular risk (Peters, Frohlich et al. 2001; Miller, Siscovick et al. 2007). Although the mechanisms by which exposure to PM induces cardiac ischemic events such as myocardial infarctions are not yet well defined, several studies have suggested that PM can be associated with hemodynamic, hemostatic as well as cardiac rhythm alterations that may account for some of the PM-induced acute cardiac events. In support of this observation, there are significant associations between exposure to ambient PM and acceleration of heart rate, diminished heart rate variability (Pope and Kalkstein 1996; Peters, Doring et al. 1997), ventricular fibrillation, increased number of therapeutic intervention in patients with implanted cardiovascular-defibrillators (Peters, Liu et al. 2000) and increased plasma viscosity (Peters, Doring et al. 1997). Many studies have also reported a strong correlation between long-term exposure to PM 2.5 and cardiac ischemic endpoints as shown above, which strongly suggests that PMenhancement of atherosclerosis could be one of the pathogenic mechanism(s). Indeed, several studies involving human subjects have shown significant associations between PM 2.5 exposure and atherosclerosis. Thus, in a cross-sectional study carried out in 798 individuals in Los Angeles by Kunzli et al, carotid intima-medial thickness (CIMT) was found to increase by 5.9% for every 10 µg/m 3 rise in PM 2.5 levels (Kunzli, Jerrett et al. 2005). Same group found an acceleration in the annual rate progression of CIMT among individual living within 100 m of a highway which was more than twice the population mean progression (Kunzli, Jerrett et al. 2010). In another study, Hoffman et al found an association between coronary artery calcification (CAC) scores, an index of coronary atherosclerosis, and long-term residential exposure to high traffic (Hoffmann, Moebus et al. 2007). They found that in 4,494 participants, subjects living within 101-200 m, 51-100 or less than 50 m from a major road showed 8%, 34% and 63% increase respectively in the probability of having CAC compared with subjects living >200 m. Furthermore, Diez Roux et al reported a 1-3% increase in CIMT per 21 µg/m 3 increase in PM 10 or 12.5 µg/m 3 increase in PM 2.5 in subjects exposed to PM 10 over long-term (20-year means and 2001 mean) and 20-year PM 2.5 respectively (Diez Roux, Auchincloss et al. 2008). Likewise, in a related study, Allen et al reported an increase risk for aortic calcification with PM 2.5 exposure (Allen, Criqui et al. 2009). All these studies confirm that exposure to PM triggers-off the development of atherosclerosis in humans, which may be a major mechanism how long-term exposure to PM leads to enhanced cardiovascular ischemic endpoints. Three putative ”general mediating” pathways (Fig.1) have been proposed for the cardiovascular effects of air pollutants such as: 1) Autonomic nervous system imbalance, 2) Induction of pumonary and thereby systemic inflammation/oxidative stress via ”spill-over” of mediators (e.g. cytokines, activated white cells/platelets) into the systemic circulation, 3) Access of particles or specific chemical constituents into the systemic circulation which thereby cause direct affects upon the heart and vasculature (Araujo and Brook 2011) (Fig.1). Some of the PM-mediated short-term effects may be related to pathway #1. On the other hand, the occurrance of long-term effects strongly suggests that PM would promote atherosclerosis, likely via a combination of pathway #2 and #3. However, while it has been proposed that UFP could access the systemic circulation (pathway #3), clear confirmation of this possibility is still lacking.
Particulate Matter and Cardiovascular Health Effects 377 1 Air Pollution 3 2 Pulmonary Reflexes Particle Translocation ? Pulmonary Inflammation Autonomic Nervous System ? EC dysfunction Oxidative Systemic Stress Inflammation Platelets Atherothrombosis Coagulation Atherosclerosis Sympathetic / Parasympathetic Effects Dysrhythmias CHF CVA PVD IHD Increased CV Morbidity & Mortality Fig. 1. Possible mechanisms that link exposure to PM with cardiovascular diseases. Three mediating pathways are proposed. Air pollution can; 1) Activate the autonomic nervous system resulting in the alteration of heart rate viability and induction of dysrhythmias, 2) Enhance atherothrombotic processes that can lead to development of pulmonary oxidative stress and inflammation with systemic “spill-over” of inflammatory mediators, 3) Particles and/or their chemical constituents can translocate directly to the systemic circulation. CHF= Congestive heart failure, CVA= Cerebrovascular accident, PVD= Peripheral vascular disease, EC= Endothelial cells, IHD= Ischemic heart disease. Taken from (Araujo and Brook 2011). It is possible then that the predominant mechanism(s) mediating PM-enhancement of cardiovascular ischemic events could be different among studies that evaluate short- vs. long-term effects. In addition, particulate of different size fractions as well as originating from different sources could exhibit significant differences in their ability to induce systemic vascular effects as will be discussed in the next two sections below.
Page 1 and 2:
AIR POLLUTION - MONITORING, MODELLI
Page 5 and 6:
Contents Preface IX Chapter 1 Urban
Page 9:
Preface This book provides a compre
Page 12 and 13:
2 Air Pollution - Monitoring, Model
Page 14 and 15:
Page 16 and 17:
Page 18 and 19:
Page 20 and 21:
10 Air Pollution - Monitoring, Mode
Page 22 and 23:
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37:
Page 38 and 39:
Page 40 and 41:
Page 42 and 43:
Page 44 and 45:
Page 46 and 47:
Page 48 and 49:
Page 50 and 51:
Page 52 and 53:
Page 54 and 55:
Page 56 and 57:
Page 58 and 59:
Page 60 and 61:
Page 62 and 63:
Page 64 and 65:
Page 66 and 67:
Page 68 and 69:
Page 70 and 71:
Page 72 and 73:
Page 74 and 75:
Page 76 and 77:
Page 78 and 79:
Page 80 and 81:
Page 82 and 83:
Page 84 and 85:
Page 86 and 87:
Page 88 and 89:
Page 90 and 91:
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
100 Air Pollution - Monitoring, Mod
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
Page 190 and 191:
Page 192 and 193:
Page 194 and 195:
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
Page 260 and 261:
Page 262 and 263:
Page 264 and 265:
Page 266 and 267:
Page 268 and 269:
Page 270 and 271:
Page 272 and 273:
Page 274 and 275:
Page 276 and 277:
Page 278 and 279:
Page 280 and 281:
Page 282 and 283:
Page 284 and 285:
Page 286 and 287:
Page 288 and 289:
Page 290 and 291:
Page 292 and 293:
Page 294 and 295:
Page 296 and 297:
Page 298 and 299:
Page 300 and 301:
Page 302 and 303:
Page 304 and 305:
Page 306 and 307:
Page 308 and 309:
Page 310 and 311:
Page 312 and 313:
Page 314 and 315:
Page 316 and 317:
Page 318 and 319:
Page 320 and 321:
Page 322 and 323:
Page 324 and 325:
Page 326 and 327:
Page 328 and 329:
Page 330 and 331:
Page 332 and 333:
Page 334 and 335:
Page 336 and 337: 326 Air Pollution - Monitoring, Mod
Page 396: 386 Air Pollution - Monitoring, Mod
show all

AIR POLLUTION – MONITORING MODELLING AND HEALTH

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?