Human caused air pollution exposure, annual growth rate by country
The year-on-year percentage change in Human caused air pollution exposure. Computed from consecutive annual observations; years either side of a gap are skipped rather than bridged.
Countries reporting
240
Highest
36.79 % change on previous year
Rwanda
Lowest
-49.28 % change on previous year
Palau
Median
2.29 % change on previous year
Years covered
26
1999–2024
Data points
6,240
What the numbers show
Human caused air pollution exposure, annual growth rate is currently reported for 240 countries. The highest value is 36.79 % change on previous year in Rwanda; the lowest is -49.28 % change on previous year in Palau.
The median across all reporting countries is 2.29 % change on previous year, and the mean is 1.1 % change on previous year.
Over the past decade 125 countries rose and 112 fell. The largest increase was in Eritrea (up 9,294.8%), and the largest decrease in United States (down 3,856.8%).
Human caused air pollution exposure, annual growth rate: full country ranking
| # | Country | Latest | Year | 10-year change | Trend |
|---|---|---|---|---|---|
| 1 | Rwanda | 36.79 % change on previous year | 2024 | up 707.3% | volatile |
| 2 | Bolivia | 36.72 % change on previous year | 2024 | up 675.8% | volatile |
| 3 | Burundi | 35.51 % change on previous year | 2024 | up 892.7% | volatile |
| 4 | Uganda | 31.94 % change on previous year | 2024 | up 417.6% | volatile |
| 5 | Democratic Republic of Congo | 31.23 % change on previous year | 2024 | up 346.8% | volatile |
| 6 | Congo | 27.57 % change on previous year | 2024 | up 321.7% | volatile |
| 7 | Tanzania | 24.35 % change on previous year | 2024 | up 594.2% | volatile |
| 8 | Kenya | 21 % change on previous year | 2024 | up 300.4% | volatile |
| 9 | Paraguay | 20.48 % change on previous year | 2024 | up 55.8% | volatile |
| 10 | South Sudan | 20.2 % change on previous year | 2024 | up 389.5% | volatile |
| 11 | Denmark | 19.77 % change on previous year | 2024 | up 5.1% | volatile |
| 12 | Gabon | 19.2 % change on previous year | 2024 | up 220.8% | volatile |
| 13 | Portugal | 17.75 % change on previous year | 2024 | up 215.2% | volatile |
| 14 | Saint Helena | 17.7 % change on previous year | 2024 | up 378.2% | volatile |
| 15 | Comoros | 17.41 % change on previous year | 2024 | up 212.4% | volatile |
| 16 | Bulgaria | 17.21 % change on previous year | 2024 | up 775.2% | volatile |
| 17 | Trinidad and Tobago | 17.13 % change on previous year | 2024 | up 359.8% | volatile |
| 18 | Belize | 16.21 % change on previous year | 2024 | up 297.5% | volatile |
| 19 | Equatorial Guinea | 15.77 % change on previous year | 2024 | up 245.0% | volatile |
| 20 | Sao Tome and Principe | 14.99 % change on previous year | 2024 | up 160.6% | volatile |
| 21 | Costa Rica | 14.79 % change on previous year | 2024 | up 337.2% | volatile |
| 22 | Liberia | 14.78 % change on previous year | 2024 | up 284.9% | volatile |
| 23 | Central African Republic | 14.68 % change on previous year | 2024 | up 233.1% | volatile |
| 24 | Guyana | 14.64 % change on previous year | 2024 | up 569.1% | volatile |
| 25 | South Korea | 13.9 % change on previous year | 2024 | up 137.2% | volatile |
| 26 | Ecuador | 13.43 % change on previous year | 2024 | up 984.2% | volatile |
| 27 | Curacao | 13.2 % change on previous year | 2024 | up 245.8% | volatile |
| 28 | Aruba | 12.68 % change on previous year | 2024 | up 234.0% | volatile |
| 29 | Panama | 12.38 % change on previous year | 2024 | — | volatile |
| 30 | Sierra Leone | 12.18 % change on previous year | 2024 | up 2,881.2% | volatile |
| 31 | Nicaragua | 12.14 % change on previous year | 2024 | up 177.0% | volatile |
| 32 | Bosnia and Herzegovina | 12.01 % change on previous year | 2024 | up 230.5% | volatile |
| 33 | Barbados | 11.9 % change on previous year | 2024 | up 294.1% | volatile |
| 34 | Togo | 11.87 % change on previous year | 2024 | up 463.5% | volatile |
| 35 | Northern Mariana Islands | 11.76 % change on previous year | 2024 | down 59.1% | volatile |
| 36 | Yemen | 11.66 % change on previous year | 2024 | up 209.7% | volatile |
| 37 | Brazil | 11.57 % change on previous year | 2024 | up 1,041.6% | volatile |
| 38 | Peru | 11.12 % change on previous year | 2024 | up 457.2% | volatile |
| 39 | Netherlands | 11.07 % change on previous year | 2024 | up 659.4% | volatile |
| 40 | Angola | 10.93 % change on previous year | 2024 | up 200.3% | volatile |
| 41 | Burkina Faso | 10.67 % change on previous year | 2024 | up 23.2% | volatile |
| 42 | Sweden | 10.64 % change on previous year | 2024 | down 59.9% | volatile |
| 43 | Egypt | 10.5 % change on previous year | 2024 | up 195.3% | volatile |
| 44 | El Salvador | 10.35 % change on previous year | 2024 | up 187.9% | volatile |
| 45 | Saint Vincent and the Grenadines | 10.16 % change on previous year | 2024 | up 84.2% | volatile |
| 46 | Sudan | 10.01 % change on previous year | 2024 | down 23.6% | volatile |
| 47 | Ghana | 9.94 % change on previous year | 2024 | up 285.2% | volatile |
| 48 | Albania | 9.9 % change on previous year | 2024 | up 256.7% | volatile |
| 49 | Dominican Republic | 9.84 % change on previous year | 2024 | down 32.9% | volatile |
| 50 | Honduras | 9.6 % change on previous year | 2024 | up 165.8% | volatile |
| 51 | Armenia | 9.39 % change on previous year | 2024 | up 92.2% | volatile |
| 52 | Venezuela | 9.25 % change on previous year | 2024 | up 561.6% | volatile |
| 53 | Bonaire Sint Eustatius and Saba | 9.13 % change on previous year | 2024 | up 401.3% | volatile |
| 54 | Grenada | 9.12 % change on previous year | 2024 | up 390.6% | volatile |
| 55 | Ethiopia | 8.99 % change on previous year | 2024 | up 248.0% | volatile |
| 56 | Guinea-Bissau | 8.48 % change on previous year | 2024 | up 2.9% | volatile |
| 57 | Puerto Rico | 8.43 % change on previous year | 2024 | down 16.7% | volatile |
| 58 | French Guiana | 8.42 % change on previous year | 2024 | up 273.2% | volatile |
| 59 | British Virgin Islands | 8.1 % change on previous year | 2024 | down 16.5% | volatile |
| 60 | Suriname | 8.04 % change on previous year | 2024 | — | volatile |
| 61 | Georgia | 7.96 % change on previous year | 2024 | up 47.3% | volatile |
| 62 | Cote d'Ivoire | 7.85 % change on previous year | 2024 | up 200.5% | volatile |
| 63 | Serbia | 7.82 % change on previous year | 2024 | up 161.5% | volatile |
| 64 | Norway | 7.79 % change on previous year | 2024 | up 12.4% | volatile |
| 65 | Benin | 7.77 % change on previous year | 2024 | up 265.1% | volatile |
| 66 | Croatia | 7.55 % change on previous year | 2024 | up 158.4% | volatile |
| 67 | Malawi | 7.49 % change on previous year | 2024 | up 155.1% | volatile |
| 68 | Haiti | 7.3 % change on previous year | 2024 | down 1.4% | volatile |
| 69 | Colombia | 7.26 % change on previous year | 2024 | down 19.0% | volatile |
| 70 | Palestine | 7.22 % change on previous year | 2024 | up 1,712.4% | volatile |
| 71 | Pakistan | 7.2 % change on previous year | 2024 | up 251.8% | volatile |
| 72 | Germany | 7.15 % change on previous year | 2024 | up 580.3% | volatile |
| 73 | Dominica | 7.12 % change on previous year | 2024 | down 32.5% | volatile |
| 74 | Guatemala | 7.12 % change on previous year | 2024 | up 157.8% | volatile |
| 75 | Jordan | 7.1 % change on previous year | 2024 | up 269.6% | volatile |
| 76 | Mexico | 7.08 % change on previous year | 2024 | up 197.3% | volatile |
| 77 | Gambia | 7 % change on previous year | 2024 | up 2,438.1% | volatile |
| 78 | United States Virgin Islands | 6.86 % change on previous year | 2024 | down 21.7% | volatile |
| 79 | Djibouti | 6.75 % change on previous year | 2024 | up 309.9% | volatile |
| 80 | Namibia | 6.68 % change on previous year | 2024 | up 206.3% | volatile |
| 81 | Eswatini | 6.47 % change on previous year | 2024 | up 1,263.2% | volatile |
| 82 | Mayotte | 6.42 % change on previous year | 2024 | up 130.0% | volatile |
| 83 | Guadeloupe | 6.28 % change on previous year | 2024 | down 57.8% | volatile |
| 84 | Slovenia | 6.18 % change on previous year | 2024 | up 140.7% | volatile |
| 85 | Afghanistan | 6.07 % change on previous year | 2024 | up 884.2% | volatile |
| 86 | Austria | 5.94 % change on previous year | 2024 | up 143.9% | volatile |
| 87 | Guinea | 5.92 % change on previous year | 2024 | up 2.1% | volatile |
| 88 | Ireland | 5.82 % change on previous year | 2024 | up 130.9% | volatile |
| 89 | North Korea | 5.73 % change on previous year | 2024 | down 82.5% | volatile |
| 90 | Montserrat | 5.73 % change on previous year | 2024 | down 62.8% | volatile |
| 91 | Hungary | 5.58 % change on previous year | 2024 | up 203.8% | volatile |
| 92 | Philippines | 5.52 % change on previous year | 2024 | up 4.2% | volatile |
| 93 | Aland Islands | 5.48 % change on previous year | 2024 | down 81.0% | volatile |
| 94 | Saint Lucia | 5.46 % change on previous year | 2024 | down 17.2% | volatile |
| 95 | Belgium | 5.45 % change on previous year | 2024 | up 129.3% | volatile |
| 96 | Syria | 5.19 % change on previous year | 2024 | up 429.5% | volatile |
| 97 | Mozambique | 5.13 % change on previous year | 2024 | up 200.7% | volatile |
| 98 | Eritrea | 5.04 % change on previous year | 2024 | up 9,294.8% | volatile |
| 99 | Sri Lanka | 4.97 % change on previous year | 2024 | up 987.7% | volatile |
| 100 | Zambia | 4.64 % change on previous year | 2024 | up 268.7% | volatile |
| 101 | Czechia | 4.47 % change on previous year | 2024 | up 259.3% | volatile |
| 102 | Libya | 4.24 % change on previous year | 2024 | up 135.7% | volatile |
| 103 | New Zealand | 4.2 % change on previous year | 2024 | up 140.4% | volatile |
| 104 | San Marino | 4.06 % change on previous year | 2024 | up 119.3% | volatile |
| 105 | Lithuania | 4.02 % change on previous year | 2024 | down 62.4% | volatile |
| 106 | Israel | 4 % change on previous year | 2024 | up 305.8% | volatile |
| 107 | Isle of Man | 3.97 % change on previous year | 2024 | up 123.0% | volatile |
| 108 | South Africa | 3.85 % change on previous year | 2024 | up 74.8% | volatile |
| 109 | Botswana | 3.78 % change on previous year | 2024 | up 137.9% | volatile |
| 110 | Montenegro | 3.74 % change on previous year | 2024 | up 159.9% | volatile |
| 111 | Martinique | 3.7 % change on previous year | 2024 | down 66.1% | volatile |
| 112 | Senegal | 3.67 % change on previous year | 2024 | up 230.0% | volatile |
| 113 | Antigua and Barbuda | 3.63 % change on previous year | 2024 | down 74.4% | volatile |
| 114 | Finland | 2.92 % change on previous year | 2024 | down 76.5% | volatile |
| 115 | Saint Martin (French Part) | 2.58 % change on previous year | 2024 | down 87.3% | volatile |
| 116 | Luxembourg | 2.54 % change on previous year | 2024 | up 115.3% | volatile |
| 117 | Poland | 2.51 % change on previous year | 2024 | down 31.8% | volatile |
| 118 | Zimbabwe | 2.44 % change on previous year | 2024 | up 144.5% | volatile |
| 119 | Mali | 2.41 % change on previous year | 2024 | down 85.7% | volatile |
| 120 | French Polynesia | 2.4 % change on previous year | 2024 | down 79.4% | volatile |
| 121 | Cameroon | 2.17 % change on previous year | 2024 | up 140.0% | volatile |
| 122 | Sint Maarten (Dutch part) | 2.16 % change on previous year | 2024 | down 88.1% | volatile |
| 123 | Anguilla | 2.07 % change on previous year | 2024 | down 90.4% | volatile |
| 124 | Belarus | 1.94 % change on previous year | 2024 | down 83.5% | volatile |
| 125 | Cyprus | 1.81 % change on previous year | 2024 | up 397.1% | volatile |
| 126 | Turkey | 1.73 % change on previous year | 2024 | down 68.0% | volatile |
| 127 | Ukraine | 1.72 % change on previous year | 2024 | up 217.1% | volatile |
| 128 | Nigeria | 1.39 % change on previous year | 2024 | up 131.6% | volatile |
| 129 | Italy | 0.9834 % change on previous year | 2024 | up 105.6% | volatile |
| 130 | Oman | 0.9294 % change on previous year | 2024 | down 83.8% | volatile |
| 131 | Estonia | 0.8264 % change on previous year | 2024 | down 89.8% | volatile |
| 131 | Russia | 0.8264 % change on previous year | 2024 | down 88.0% | volatile |
| 133 | Azerbaijan | 0.7286 % change on previous year | 2024 | down 69.3% | volatile |
| 134 | Falkland Islands | 0.7168 % change on previous year | 2024 | down 95.6% | volatile |
| 135 | Iran | 0.5247 % change on previous year | 2024 | down 88.0% | volatile |
| 136 | Bhutan | 0.519 % change on previous year | 2024 | down 96.9% | volatile |
| 137 | Turkmenistan | 0.4752 % change on previous year | 2024 | down 91.5% | volatile |
| 138 | Madagascar | 0.4435 % change on previous year | 2024 | up 104.3% | volatile |
| 139 | Saint Kitts and Nevis | 0.3311 % change on previous year | 2024 | down 98.2% | volatile |
| 140 | Argentina | 0.2268 % change on previous year | 2024 | up 156.6% | volatile |
| 141 | Niger | -0.0654 % change on previous year | 2024 | down 120.7% | volatile |
| 142 | Liechtenstein | -0.0974 % change on previous year | 2024 | up 99.5% | volatile |
| 143 | Lebanon | -0.149 % change on previous year | 2024 | up 91.0% | volatile |
| 144 | Saudi Arabia | -0.3189 % change on previous year | 2024 | down 104.0% | volatile |
| 145 | China | -0.5382 % change on previous year | 2024 | down 106.6% | volatile |
| 146 | Saint Barthelemy | -0.7194 % change on previous year | 2024 | down 104.2% | volatile |
| 147 | Chad | -0.87 % change on previous year | 2024 | up 76.8% | volatile |
| 148 | United Kingdom | -0.894 % change on previous year | 2024 | up 79.4% | volatile |
| 149 | Jamaica | -0.9038 % change on previous year | 2024 | down 111.2% | volatile |
| 150 | Mongolia | -1.01 % change on previous year | 2024 | up 80.3% | volatile |
| 151 | Cuba | -1.23 % change on previous year | 2024 | down 115.0% | volatile |
| 152 | Malaysia | -1.28 % change on previous year | 2024 | down 109.9% | volatile |
| 153 | Slovakia | -1.47 % change on previous year | 2024 | up 80.9% | volatile |
| 154 | Switzerland | -2 % change on previous year | 2024 | up 89.0% | volatile |
| 155 | Nepal | -2.17 % change on previous year | 2024 | down 175.5% | volatile |
| 156 | Australia | -2.51 % change on previous year | 2024 | down 136.9% | volatile |
| 157 | Malta | -2.53 % change on previous year | 2024 | up 79.2% | volatile |
| 158 | North Macedonia | -2.66 % change on previous year | 2024 | up 73.9% | volatile |
| 159 | Kazakhstan | -2.76 % change on previous year | 2024 | down 841.2% | volatile |
| 160 | Singapore | -2.8 % change on previous year | 2024 | up 80.1% | volatile |
| 161 | Romania | -2.91 % change on previous year | 2024 | down 83.9% | volatile |
| 162 | Uzbekistan | -2.95 % change on previous year | 2024 | down 186.1% | volatile |
| 163 | United Arab Emirates | -3.07 % change on previous year | 2024 | down 161.3% | volatile |
| 164 | Cape Verde | -3.15 % change on previous year | 2024 | up 59.1% | volatile |
| 165 | Brunei | -3.21 % change on previous year | 2024 | down 122.2% | volatile |
| 166 | Pitcairn | -3.53 % change on previous year | 2024 | up 23.2% | volatile |
| 167 | Uruguay | -3.66 % change on previous year | 2024 | down 146.5% | volatile |
| 168 | Papua New Guinea | -3.75 % change on previous year | 2024 | down 24.0% | volatile |
| 169 | Iraq | -3.98 % change on previous year | 2024 | down 192.1% | volatile |
| 170 | Cambodia | -3.99 % change on previous year | 2024 | up 28.1% | volatile |
| 171 | Somalia | -4 % change on previous year | 2024 | down 232.6% | volatile |
| 172 | Greece | -4.07 % change on previous year | 2024 | down 164.7% | volatile |
| 173 | Mauritania | -4.19 % change on previous year | 2024 | down 228.4% | volatile |
| 174 | Latvia | -4.2 % change on previous year | 2024 | down 145.3% | volatile |
| 175 | Vietnam | -4.29 % change on previous year | 2024 | down 2,945.4% | volatile |
| 176 | Qatar | -4.5 % change on previous year | 2024 | down 279.3% | volatile |
| 177 | Chile | -4.56 % change on previous year | 2024 | down 247.5% | volatile |
| 178 | Monaco | -4.65 % change on previous year | 2024 | up 69.9% | volatile |
| 179 | Indonesia | -4.74 % change on previous year | 2024 | down 115.4% | volatile |
| 180 | Western Sahara | -5.06 % change on previous year | 2024 | down 147.0% | volatile |
| 181 | Spain | -5.1 % change on previous year | 2024 | up 50.3% | volatile |
| 182 | Thailand | -5.36 % change on previous year | 2024 | down 36.7% | volatile |
| 183 | Tajikistan | -5.46 % change on previous year | 2024 | down 188.7% | volatile |
| 184 | Lesotho | -5.49 % change on previous year | 2024 | down 811.8% | volatile |
| 185 | France | -5.66 % change on previous year | 2024 | up 74.2% | volatile |
| 186 | Moldova | -5.79 % change on previous year | 2024 | down 561.3% | volatile |
| 187 | Japan | -5.84 % change on previous year | 2024 | down 230.1% | volatile |
| 188 | India | -6.08 % change on previous year | 2024 | down 305.0% | volatile |
| 189 | Bahamas | -6.46 % change on previous year | 2024 | down 169.7% | volatile |
| 190 | Bangladesh | -6.61 % change on previous year | 2024 | down 202.7% | volatile |
| 191 | Myanmar | -7.23 % change on previous year | 2024 | down 316.1% | volatile |
| 192 | Reunion | -7.96 % change on previous year | 2024 | up 34.2% | volatile |
| 193 | Norfolk Island | -8.06 % change on previous year | 2024 | down 170.2% | volatile |
| 194 | Turks and Caicos Islands | -8.27 % change on previous year | 2024 | down 211.4% | volatile |
| 195 | Bahrain | -8.61 % change on previous year | 2024 | down 393.3% | volatile |
| 196 | Kuwait | -9.05 % change on previous year | 2024 | down 165.4% | volatile |
| 197 | Fiji | -9.09 % change on previous year | 2024 | down 307.6% | volatile |
| 198 | Kyrgyzstan | -9.12 % change on previous year | 2024 | up 8.0% | volatile |
| 199 | Vatican | -9.26 % change on previous year | 2024 | up 59.4% | volatile |
| 200 | Faroe Islands | -9.61 % change on previous year | 2024 | down 164.6% | volatile |
| 201 | Laos | -9.76 % change on previous year | 2024 | down 309.2% | volatile |
| 202 | Gibraltar | -10.12 % change on previous year | 2024 | up 21.0% | volatile |
| 203 | Cook Islands | -10.24 % change on previous year | 2024 | down 169.6% | volatile |
| 204 | Maldives | -10.26 % change on previous year | 2024 | down 179.8% | volatile |
| 205 | Seychelles | -10.3 % change on previous year | 2024 | down 341.2% | volatile |
| 206 | Niue | -11.11 % change on previous year | 2024 | down 444.4% | volatile |
| 207 | Guam | -11.27 % change on previous year | 2024 | down 127.4% | volatile |
| 208 | Jersey | -11.42 % change on previous year | 2024 | up 18.1% | volatile |
| 209 | Mauritius | -11.51 % change on previous year | 2024 | down 54.9% | volatile |
| 210 | Tonga | -11.63 % change on previous year | 2024 | down 27.9% | volatile |
| 211 | Guernsey | -11.63 % change on previous year | 2024 | down 1.0% | volatile |
| 212 | East Timor | -11.83 % change on previous year | 2024 | down 144.3% | volatile |
| 213 | Cayman Islands | -12.1 % change on previous year | 2024 | down 242.7% | volatile |
| 214 | Vanuatu | -12.17 % change on previous year | 2024 | down 591.8% | volatile |
| 215 | Tunisia | -12.18 % change on previous year | 2024 | up 13.3% | volatile |
| 216 | Andorra | -13.11 % change on previous year | 2024 | down 30.3% | volatile |
| 217 | Solomon Islands | -13.13 % change on previous year | 2024 | down 1,994.7% | volatile |
| 218 | Algeria | -13.36 % change on previous year | 2024 | down 24.7% | volatile |
| 219 | Tokelau | -13.39 % change on previous year | 2024 | down 182.3% | volatile |
| 220 | Morocco | -13.75 % change on previous year | 2024 | up 7.8% | volatile |
| 221 | American Samoa | -14.18 % change on previous year | 2024 | down 206.9% | volatile |
| 222 | Samoa | -14.38 % change on previous year | 2024 | down 180.3% | volatile |
| 223 | New Caledonia | -14.45 % change on previous year | 2024 | down 546.6% | volatile |
| 224 | Marshall Islands | -14.47 % change on previous year | 2024 | down 179.1% | volatile |
| 225 | United States | -14.82 % change on previous year | 2024 | down 3,856.8% | volatile |
| 226 | Tuvalu | -15.84 % change on previous year | 2024 | down 156.1% | volatile |
| 227 | Iceland | -16.76 % change on previous year | 2024 | down 279.5% | volatile |
| 228 | Taiwan | -17.8 % change on previous year | 2024 | down 175.7% | volatile |
| 229 | Saint Pierre and Miquelon | -18.4 % change on previous year | 2024 | down 15.1% | volatile |
| 230 | Wallis and Futuna | -20.77 % change on previous year | 2024 | down 310.4% | volatile |
| 231 | United States Minor Outlying Islands | -27.51 % change on previous year | 2024 | down 1,660.6% | volatile |
| 232 | Canada | -28.62 % change on previous year | 2024 | down 949.8% | volatile |
| 233 | Nauru | -29.28 % change on previous year | 2024 | down 162.3% | volatile |
| 234 | Christmas Island | -29.73 % change on previous year | 2024 | down 154.1% | volatile |
| 235 | Cocos Islands | -33.46 % change on previous year | 2024 | down 3,311.8% | volatile |
| 236 | Kiribati | -35.22 % change on previous year | 2024 | down 238.7% | volatile |
| 237 | Micronesia (country) | -35.42 % change on previous year | 2024 | down 161.0% | volatile |
| 238 | Bermuda | -36.07 % change on previous year | 2024 | down 365.3% | volatile |
| 239 | Greenland | -38.06 % change on previous year | 2024 | — | volatile |
| 240 | Palau | -49.28 % change on previous year | 2024 | down 175.2% | volatile |
How this figure is calculated
The year-on-year percentage change in Human caused air pollution exposure. Computed from consecutive annual observations; years either side of a gap are skipped rather than bridged.
Computed from
- Human caused air pollution exposure Our World in Data
Statizoid computes this series; the underlying measurements belong to the publishers named above. The arithmetic is applied to every country and year where both inputs report, and nothing is estimated unless the page says so.
About this data
The year-on-year percentage change in Human caused air pollution exposure. Computed from consecutive annual observations; years either side of a gap are skipped rather than bridged.