Abstract
Background:
Today, air pollution is a major issue in the world, particularly in metropolitan areas.Objectives:
Accordingly, this study aimed to investigate the relation between air pollution and mortality in the elderly in Kerman City.Methods:
This ecological study was conducted using 2006 - 2013 mortality data inquired from the Deputy of Health of Kerman University of Medical Sciences. The data on cardiovascular and respiratory mortality, as well as death due to trauma, diabetes, and other diseases that happened in men and women aged 60 and higher were extracted. Air pollution data (CO, SO2, O3, NO, NO2, NOx, and PM10) for the same time frame were inquired from the Environmental Protection Agency of Kerman Province. Negative binomial regression was used to evaluate the relation between air pollutants and mortality using STATA13 software.Results:
During the study period, a total of 14,793 deaths occurred in elderly men and women in Kerman City. Cardiovascular diseases were the leading cause of death. The results of multivariate analysis of air pollutants indicated that NO was directly and significantly related to the total number of deaths in the elderly, and increase in sulfur dioxide, ozone and NO was significantly related to increased mortality among elderly women. Carbon monoxide was significantly related to cardiovascular death of the elderly. But air pollutants did not show any significant effect on respiratory-, trauma-, and diabetes-related deaths.Conclusions:
Our findings indicate that there is a significant relation between air pollution and mortality in the elderly. Accordingly, a warning system is suggested to reduce the elderly’s commuting on highly air polluted days.Keywords
Cardiovascular Death Respiratory Death Diabetes Trauma Elderly Kerman
1. Background
Today, air pollution is one of the major environmental issues in the world’s major cities and is jeopardizing the living conditions of human beings (1, 2). High population growth and increased energy consumption, rapid economic and urban development, expansion of urban traffic, inappropriate use of industrial systems and devices, and non-compliance with environmental regulations has resulted in air pollution in many countries (3).
According to the World Health Organization (WHO), approximately 3 million people lose their lives annually due to air pollution (4). WHO has estimated that exposure to particulate matter causes more than 500,000 premature deaths per year. The numerous adverse events that have occurred as a result of air pollution in the world can appropriately highlight the importance of this issue. In October 1948, sulfur dioxide (SO2) and industrial dust caused the death of 20 people and sickened almost 6,000 people in Pennsylvania. In London in December 1952, burning coal in homes and SO2 emissions along with inversion and air pollution entrapment caused the death of 4000 people. In December 1962, again air pollution in London took the lives of 300 people (3).
It seems air pollution has a very comprehensive impact on human health. The severe effects of carbon monoxide (CO) on human health include increased mortality due to heart and respiratory diseases, stroke, and acute heart attacks. Studies have shown a relation between respiratory diseases and environmental pollution in industrialized countries as well as countries with low or moderate income. Therefore, air pollution is nowadays a major global environmental health problem (5).
One of the groups that are likely to be more susceptible to air pollution is the elderly. A previous analysis of an elderly cohort in Hong Kong revealed that long-term exposure to PM2.5 and black carbon was associated with cardiovascular mortality, but not respiratory mortality, among an elderly population in Hong Kong, a high-density and high-rise city in Asia, and effect estimates remained similar for various time exposure windows (6). Yap et al. (7) conducted a time series study in Singapore and revealed that particulate air pollutants (PM2.5, PM10) were associated with non-accidental mortality and cardiovascular mortality, and the effects were greater on the elderly. Another study in Montreal showed positive associations between daily non-accidental mortality and all air pollutants, except ozone. They also noticed that people with cardiovascular disease, congestive heart failure, atrial fibrillation, diabetes, and cardiovascular disease are more likely to die from air pollution (8).
2. Objectives
This study aimed to investigate the relation between air pollution and elderly death in Kerman, Iran. This was the first study of this kind done in Kerman. Kerman City is one of the major cities of Iran located in the southeast, with a population of over 621,374 individuals according to the 2011 census (9).
3. Methods
This was an ecological study conducted in Kerman city. Initially, data on the number of deaths in the elderly per day, from 2006 until 2013 were inquired from the Deputy of Health of Kerman University of Medical Sciences. Elderly deaths were deaths that occurred due to any reason in people aged 60 and older. Then, these deaths were classified based on gender (male and female) and the cause of death (cardiovascular disease, respiratory diseases, trauma, diabetes, and other diseases).
Data on air pollution (including NO, CO, NO2, NOx, PM10, SO2, and O3) were inquired from the Environmental Protection Agency of Kerman Province. These data are measured on a daily basis using a fixed station within the city. In this study, observations that were more than ± 3 SD away from the mean were recognized as outliers and were dealt with as missing data. Then missing air pollution data were estimated using the expectation-maximization (EM) algorithm in SPSS20 software. Details of these methods can be found in our previous publications (10). This study was approved by the Standing Committee on Ethics in Research of Kerman University of Medical Sciences (ethics code: IR.KMU.REC.1394.428). The relation between daily mortality and air pollution was analyzed using negative binomial regression in STATA13.
4. Results
During this time, 6465, 2958, 1017, 895, and 3458 deaths caused by cardiovascular diseases, respiratory diseases, trauma, diabetes, and other reasons, respectively, occurred among the elderly in Kerman. The numbers of deaths have been categorized on the basis of year and gender in Table 1. The average air pollutants during these seven years are shown in Table 2. The relation between daily levels of air pollutants and deaths in the elderly caused by cardiovascular diseases, respiratory diseases, trauma, diabetes, other diseases as well as the total number of diseases; categorized based on gender have been shown in Tables 3 to 8. The results of multivariate analysis of air pollutants indicated that nitrogen oxide (NO) was directly and significantly related to total numbers of deaths in the elderly; and an increase in SO2, ozone, and NO was significantly related to increased mortality among elderly women (Table 3).
The Number of Total Deaths in the Elderly From 2006 to 2013 in Kerman City
| Cause of Death | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | All Years |
|---|---|---|---|---|---|---|---|---|
| Cardiovascular diseases | ||||||||
| Total | 1184 | 946 | 619 | 986 | 1038 | 820 | 872 | 6465 |
| Men | 652 | 490 | 304 | 482 | 520 | 434 | 447 | 3329 |
| Women | 532 | 456 | 315 | 502 | 518 | 386 | 425 | 3134 |
| Respiratory diseases | ||||||||
| Total | 411 | 475 | 325 | 390 | 460 | 499 | 398 | 2958 |
| Men | 247 | 271 | 190 | 216 | 250 | 272 | 217 | 1663 |
| Women | 164 | 204 | 135 | 174 | 210 | 227 | 181 | 1295 |
| Trauma | ||||||||
| Total | 106 | 94 | 86 | 151 | 122 | 239 | 219 | 1017 |
| Men | 78 | 63 | 57 | 98 | 72 | 145 | 137 | 650 |
| Women | 28 | 31 | 29 | 53 | 50 | 94 | 82 | 367 |
| Diabetes | ||||||||
| Total | 79 | 169 | 122 | 101 | 129 | 189 | 106 | 895 |
| Men | 39 | 68 | 49 | 48 | 36 | 97 | 45 | 382 |
| Women | 40 | 101 | 73 | 53 | 93 | 92 | 61 | 513 |
| Other reasons | ||||||||
| Total | 399 | 435 | 389 | 425 | 606 | 655 | 549 | 3458 |
| Men | 227 | 255 | 205 | 235 | 346 | 365 | 318 | 1951 |
| Women | 172 | 180 | 184 | 190 | 260 | 290 | 231 | 1507 |
| All deaths | ||||||||
| Total | 2179 | 2119 | 1541 | 2053 | 2355 | 2402 | 2144 | 14793 |
| Men | 1243 | 1147 | 805 | 1081 | 1224 | 1313 | 1164 | 7977 |
| Women | 936 | 972 | 736 | 972 | 1131 | 1089 | 980 | 6817 |
Status of Pollutants in Kerman During 2006 - 2013
| Pollutants | Median | Mean | Minimum | Maximum | SD |
|---|---|---|---|---|---|
| CO, ppm | 1.01 | 1.21 | 0.109 | 5.31 | 0.70 |
| SO2, ppb | 7.45 | 8.26 | 0.10 | 70.30 | 4.66 |
| O3, ppb | 20.10 | 24.17 | 1.91 | 82.30 | 16.03 |
| NO, ppb | 9.33 | 14.06 | 0.12 | 94 | 13.92 |
| NO2, ppb | 20.25 | 19.65 | 0.16 | 43.31 | 7.35 |
| NOx, ppb | 29.29 | 33.16 | 0.20 | 112.50 | 16.69 |
| PM10, µg/m3 | 89.90 | 100.68 | 17 | 327 | 55.39 |
The Results of Negative Binomial Regression of the Impact of air Pollutants on Overall Deaths Per Day (Ratio of Increased Daily Mortality for Every Unit Increase in Average Daily Emissions)
| Pollutant | Crude IRR* and 95%CI | P-Value | Adjusted IRR and 95%CI | P-Value |
|---|---|---|---|---|
| Total | ||||
| CO, ppb | 1.02342 (0.99874 - 1.04872) | 0.063 | 0.98682 (0.94723 - 1.02808) | 0.526 |
| SO2, ppb | 1.00477 (1.00072 - 1.00884) | 0.021a | 1.00531 (0.99951 - 1.01115) | 0.073 |
| O3, ppb | 1.00030 (0.99922 - 1.00138) | 0.580 | 1.00103 (0.99761 - 1.00446) | 0.555 |
| NO, ppb | 1.00371 (1.00230 - 1.00513) | < 0.001a | 1.00335 (1.00010 - 1.00661) | 0.043a |
| NO2, ppb | 1.00162 (0.99827 - 1.00499) | 0.342 | 0.99643 (0.99120 - 1.00169) | 00.184 |
| NOx, ppb | 1.00239 (1.00120 - 1.00359) | < 0.001a | 1.00268 (0.99932 - 1.00604) | 0.117 |
| PM10, µg/m3 | 0.99933 (0.99897 - 0.99969) | < 0.001a | 0.99940 (0.99901 - 0.99980) | 0.004a |
| Men | ||||
| CO, ppb | 1.04496 (1.01090 - 1.08017) | 0.009a | 1.00741 (0.95153 - 1.06656 - | 0.800 |
| SO2, ppb | 1.00339 (0.99853 - 1.00827) | 0.171 | 1.0046 (0.99753 - 1.01187) | 0.200 |
| O3, ppb | 0.99925 (0.99777 - 1.00073) | 0.324 | 1.00574 (0.99856 - 1.00258) | 0.576 |
| NO, ppb | 1.00368 (1.00197 - 1.00539) | < 0.001a | 1.00081 (0.99682 - 1.00482) | 0.688 |
| NO2, ppb | 0.99979 (0.99731 - 1.00227) | 0.869 | 0.99441 (0.98799 - 1.00088) | 0.090 |
| NOx, ppb | 1.00301 (1.00157 - 1.00445) | < 0.001a | 1.00371 (0.99957 - 1.00787) | 0.078 |
| PM10, µg/m3 | 0.99935 (0.99890 - 0.99981) | 0.005a | 0.99922 (0.99877 - 0.99971) | 0.002a |
| Women | ||||
| CO, ppb | 0.97830 (0.94308 - 1.01484) | 0.241 | 0.93152 (0.87552 - 0.99110) | 0.025a |
| SO2, ppb | 1.00709 (1.00184 (1.01235) | 0.008a | 1.00904 (1.00137 - 1.01678) | 0.021a |
| O3, ppb | 1.00197 (1.00039 - 1.00355) | 0.015a | 1.00529 (1.00313 - 1.00980) | 0.004a |
| NO, ppb | 1.00275 (1.00088 - 1.00462) | 0.004a | 1.00536 (1.00109 - 1.00964) | 0.014a |
| NO2, ppb | 0.99792 (0.99429 - 1.00156) | 0.264 | 1.00156 (0.99467 - 1.00851) | 0.657 |
| NOx, ppb | 1.00115 (0.99955 - 1.00275) | 0.157 | 1.000421 (0.99609 - 1.00476) | 0.849 |
| PM10, µg/m3 | 0.99950 (0.99902 - 0.99998) | 0.044a | 0.99983 (0.99983 - 1.00036) | 0.542 |
The Results of Negative Binomial Regression of the Impact of Air Pollutants on Overall Daily Deaths in the Elderly Caused by Cardiovascular Diseases (Ratio of Increased Daily Mortality for Every Unit Increase in Average Daily Emissions)
| Pollutant | Crude IRR* and 95%CI | P-Value | Adjusted IRR and 95%CI | P-Value |
|---|---|---|---|---|
| Total | ||||
| CO, ppm | 1.05253 (1.01536 - 1.09106) | 0.005a | 1.07095 (1.01484 - 1.13016) | 0.013a |
| SO2, ppb | 0.99981 (0.99429 - 1.00536) | 0.948 | 1.00079 (0.99277 - 1.00889) | 0.846 |
| O3, ppb | 0.99927 (0.99764 - 1.00091) | 0.387 | 1.00061 (0.99838 - 1.00284) | 0.592 |
| NO, ppb | 0.99918 (0.99718 - 1.00118) | 0.424 | 0.99418 (0.98931 - 0.99907) | 0.020a |
| NO2, ppb | 1.00450 (1.00076 - 1.00825) | 0.018a | 1.00041 (0.99306 - 1.00781) | 0.913 |
| NOx, ppb | 1.00072 (0.99909 - 1.00235) | 0.382 | 1.00315 (0.99838 - 1.00794) | 0.195 |
| PM10, µg/m3 | 0.99961 (0.99912 - 1.00010) | 0.127 | 0.99943 (0.99888 - 0.99998) | 0.043a |
| Men | ||||
| CO, ppm | 1.043605 (0.99352 - 1.09621) | 0.089 | 1.04287 (0.96880 - 1.12259) | 0.264 |
| SO2, ppb | 0.99966 (0.99229 - 1.00709) | 0.929 | 1.00177 (0.99079 - 1.01286) | 0.753 |
| O3, ppb | 0.99955 (0.99724 - 1.00186) | 0.704 | 1.00016 (0.99704 - 1.00329) | 0.917 |
| NO, ppb | 0.99949 (0.99677 - 1.00223) | 0.719 | 0.99344 (0.98693 - 1.00000) | 0.050 |
| NO2, ppb | 1.00368 (0.99850 - 1.00888) | 0.164 | 0.997842 (0.98784 - 1.00793 | 0.674 |
| NOx, ppb | 1.00132 (0.99911 - 1.00354) | 0.239 | 1.00521 (0.99884 - 1.0116) | 0.109 |
| PM10, µg/m3 | 0.99961 (0.99891 - 1.00032) | 0.289 | 0.99947 (0.99869 - 1.00025) | 0.190 |
| Women | ||||
| CO, ppm | 1.02697 (0.97320 - 1.08372) | 0.332 | 1.05912 (0.97875 - 1.14609) | 0.154 |
| SO2, ppb | 1.00617 (0.99755 - 1.01486) | 0.161 | 1.00583 (0.99402 - 1.01777) | 0.335 |
| O3, ppb | 1.00617 (0.99807 - 1.00274) | 0.732 | 1.00205 (0.998868 - 1.005249) | 0.207 |
| NO, ppb | 0.99991 (0.99702 - 1.00281) | 0.955 | 0.99972 (0.99269 - 1.00679) | 0.939 |
| NO2, ppb | 1.00430 (0.99894 - 1.00969) | 0.116 | 1.00847 (0.99784 - 1.01920) | 0.119 |
| NOx, ppb | 1.00044 (0.99804 - 1.00284) | 0.718 | 0.99862 (0.99183 - 1.00546) | 0.693 |
| PM10, µg/m3 | 1.00002 (0.99932 - 1.00072) | 0.947 | 1.00018 (0.99941 - 1.00095) | 0.641 |
The Results of Negative Binomial Regression of the Impact of Air Pollutants on Overall Deaths in the Elderly Caused by Respiratory Diseases (Ratio of Increased Daily Mortality for Every Unit Increase in Average Daily Emissions)
| Pollutant | Crude IRR* and 95%CI | P-Value | Adjusted IRR and 95%CI | P-Value |
|---|---|---|---|---|
| Total | ||||
| CO, ppm | 1.05663 (1.00238 - 1.11382) | 0.041a | 0.99477 (0.91734 - 1.07874) | 0.899 |
| SO2, ppb | 1.00368 (0.99590 - 1.01152) | 0.354 | 1.00865 (0.99667 - 1.02077) | 0.158 |
| O3, ppb | 0.99727 (0.99478 - 0.99976) | 0.032a | 0.99806 (0.99468 - 1.00145) | 0.262 |
| NO, ppb | 1.00369 (1.00090 - 1.00644) | 0.009a | 1.00157 (0.99423 - 1.00897) | 0.675 |
| NO2, ppb | 1.00388 (0.99844 - 1.00935) | 0.162 | 0.99992 (0.98939 - 1.01057) | 0.989 |
| NOx, ppb | 1.00277 (1.00044 - 1.00510) | 0.020a | 1.00028 (0.99316 - 1.00745) | 0.938 |
| PM10, µg/m3 | 0.99971 (0.99897 - 1.00045) | 0.444 | 0.99949 (0.99867 - 1.00031) | 0.227 |
| Men | ||||
| CO, ppm | 1.05413 (0.98111 - 1.13258) | 0.150 | 0.98564 (0.88279 - 1.10047) | 0.797 |
| SO2, ppb | 0.99802 (0.98609 - 1.0101 | 0.747 | 0.99465 (0.97883 - 1.01071) | 0.512 |
| O3, ppb | 0.99793 (0.99457 - 1.00131) | 0.230 | 0.99997 (0.99538 - 1.00458) | 0.991 |
| NO, ppb | 1.00343 (0.99978 - 1.00710) | 0.065 | 1.00021 (0.99070 - 1.00981) | 0.965 |
| NO2, ppb | 1.003117 (0.99570 - 1.01058) | 0.411 | 0.99856 (0.98463 - 1.01268) | 0.841 |
| NOx, ppb | 1.00286 (0.99975 - 1.00598) | 0.071 | 1.00373 (0.99431 - 1.01324) | 0.438 |
| PM10, µg/m3 | 1.00005 (0.99909 - 1.00102) | 0.908 | 1.00016 (0.99910 - 1.00122) | 0.767 |
| Women | ||||
| CO, ppm | 1.01560 (0.93666 - 1.10118) | 0.071 | 0.98661 (0.87605 - 1.11113) | 0.824 |
| SO2, ppb | 1.00425 (0.99283 - 1.01580) | 0.467 | 1.00884 (0.99117 - 1.02682) | 0.329 |
| O3, ppb | 0.99870 (0.99508 - 1.00249) | 0.519 | 0.997976 (0.9930014 - 1.00297) | 0.427 |
| NO, ppb | 1.00174 (0.99742 - 1.00608) | 0.429 | 0.99933 (0.98899 - 1.9776) | 0.900 |
| NO2, ppb | 0.99979 (0.99163 - 1.00802) | 0.961 | 0.9940573 (0.97899 - 1.00935) | 0.444 |
| NOx, ppb | 1.00089 (0.99727 - 1.00451) | 0.630 | 1.00041 (0.99053 - 1.01038) | 0.935 |
| PM10, µg/m3 | 0.99928 (0.99813 - 1.00042) | 0.219 | 0.99921 (0.99794 - 1.00049) | 0.230 |
The Results of Negative Binomial Regression of the Impact of air Pollutants on Overall Deaths in the Elderly (Men and Women) Caused by Trauma (Ratio of Increased Daily Mortality for Every Unit Increase in Average Daily Emissions)
| Pollutant | Crude IRR* and 95%CI | P-Value | Adjusted IRR and 95%CI | P-Value |
|---|---|---|---|---|
| Total | ||||
| CO, ppm | 0.92804 (0.84031 - 1.02494) | 0.141 | 0.87778 (0.75154 - 1.02524) | 0.100 |
| SO2, ppb | 0.99915 (0.98549 - 1.01300) | 0.904 | 0.99995 (0.97762 - 1.02279) | 0.997 |
| O3, ppb | 0.99999 (0.99595 - 1.00405) | 0.999 | 0.99622 (0.99043 - 1.00203) | 0.203 |
| NO, ppb | 0.99997 (0.99498 - 1.00498) | 0.991 | 0.99992 (0.98532 - 1.01475) | 0.992 |
| NO2, ppb | 0.99324 (0.98380 - 1.00277) | 0.164 | 0.99223 (0.97231 - 1.01257) | 0.452 |
| NOx, ppb | 0.99908 (0.99475 - 1.00343) | 0.681 | 1.00025 (0.98591 - 1.01479) | 0.973 |
| PM10, µg/m3 | 0.99979 (0.99858 - 1.00101) | 0.745 | 0.99946 (0.99806 - 1.00086) | 0.451 |
| Men | ||||
| CO, ppm | 0.92107 (0.81819 - 1.03690) | 0.174 | 0.90335 (0.74883 - 1.08974) | 0.288 |
| SO2, ppb | 0.99778 (0.97893 - 1.01699) | 0.820 | 0.99750 (0.96807 - 1.02782) | 0.870 |
| O3, ppb | 1.00114 (0.99600 - 1.00631) | 0.663 | 0.99784 (0.99039 - 1.00534) | 0.573 |
| NO, ppb | 0.99782 (0.99169 - 1.00398) | 0.488 | 1.00121 (0.98111 - 1.02172) | 0.907 |
| NO2, ppb | 0.99632 (0.98475 - 1.00802) | 0.536 | 1.00356 (0.97831 - 1.02945) | 0.785 |
| NOx, ppb | 0.99772 (0.99243 - 1.00304) | 0.401 | 0.99774 (0.97792 - 1.01796) | 0.826 |
| PM10, µg/m3 | 0.99996 (0.99845 - 1.0011146) | 0.989 | 0.99947 (0.99772 - 1.00121) | 0.553 |
| Women | ||||
| CO, ppm | 0.96500 (0.799205 - 1.16651) | 0.711 | 0.92309 (0.70315 - 1.21183) | 0.564 |
| SO2, ppb | 1.00078 (0.9794024 - 1.022638) | 0.943 | 1.00220 (0.96635 - 1.03938) | 0.906 |
| O3, ppb | 1.00112 (0.99442 - 1.00787) | 0.743 | 0.99979 (0.99046 - 1.00921) | 0.966 |
| NO, ppb | 1.00128 (0.99280 - 1.00982) | 0.768 | 0.99413 (0.97200 - 1.01676) | 0.608 |
| NO2, ppb | 0.99385 (0.97696 - 1.01103 | 0.481 | 0.98418 (0.94982 - 0.01979) | 0.379 |
| NOx, ppb | 1.00093 (0.99348 - 1.00843) | 0.806 | 1.00776 (0.98597 - 1.03003) | 0.488 |
| PM10, µg/m3 | 0.9999715 (0.99801 - 1.00193) | 0.977 | 1.00001 (0.99773 - 1.00230) | 0.987 |
The Results of Negative Binomial Regression of the Impact of Air Pollutants on Overall Deaths in the Elderly (Men and Women) Caused by Diabetes (Ratio of Increased Daily Mortality for Every Unit Increase in Average Daily Emissions)
| Pollutant | Crude IRR* and 95%CI | P-Value | Adjusted IRR and 95%CI | P-Value |
|---|---|---|---|---|
| Total | ||||
| CO, ppm | 1.03085 (0.93750 - 1.33492) | 0.530 | 0.97666 (0.83972 - 1.13592) | 0.759 |
| SO2, ppb | 1.00602 (0.99180 - 1.02044) | 0.408 | 1.00168 (0.98161 - 1.02215) | 0.871 |
| O3, ppb | 1.99943 (0.99515 - 1.00373) | 0.797 | 1.00021 (0.99441 - 1.00604) | 0.943 |
| NO, ppb | 1.00263 (0.99781 - 1.00748) | 0.284 | 1.00155 (0.99082 - 1.01239) | 0.778 |
| NO2, ppb | 1.00168 (0.99198 - 1.01147) | 0.735 | 1.00018 (0.9819871 - 1.01871) | 0.985 |
| NOx, ppb | 1.00225 (0.99815 - 1.00636) | 0.282 | 1.00213 (0.99178 - 1.01259) | 0.687 |
| PM10, µg/m3 | 1.00015 (0.99891 - 1.00140) | 0.807 | 1.00010 (0.99874 - 1.00146) | 0.880 |
| Men | ||||
| CO, ppm | 1.02578 (0.88247 - 1.19237) | 0.740 | 0.99749 (0.79443 - 1.25246) | 0.983 |
| SO2, ppb | 1.00263 (0.97543 - 1.03058) | 0.851 | 0.99846 (0.96648 - 1.0315) | 0.926 |
| O3, ppb | 0.99956 (0.99298 - 1.00618) | 0.896 | 1.00048 (0.99133 - 1.00971) | 0.918 |
| NO, ppb | 1.00379 (0.99633 - 1.01132) | 0.320 | 1.00701 (0.98453 - 1.03001) | 0.544 |
| NO2, ppb | 1.000005 (0.98478 - 1.01546) | 1.000 | 1.00378 (0.96681 - 1.042165) | 0.844 |
| NOx, ppb | 1.00225 (0.99590 - 1.00864) | 0.488 | 0.997102 (0.97589 - 1.01878) | 0.792 |
| PM10, µg/m3 | 0.99971 (0.99776 - 1.00166) | 0.771 | 0.9996 (0.99752 - 1.00185) | 0.779 |
| Women | ||||
| CO, ppm | 1.00903 (0.89220 - 1.14116) | 0.886 | 0.94555 (0.76995 - 1.16119) | 0.593 |
| SO2, ppb | 1.00594 (0.98900 - 1.023182) | 0.494 | 1.00001 (0.97416 - 1.02654) | 0.999 |
| O3, ppb | 1.00005 (0.99448 - 1.00566) | 0.984 | 0.99960 (0.99208 - 1.00717) | 0.918 |
| NO, ppb | 1.000452 (0.994045 - 1.0069) | 0.890 | 1.001361 (0.98887 - 1.01400) | 0.832 |
| NO2, ppb | 1.00195 (0.98942 - 1.01463) | 0.761 | 1.00222 (0.98053 - 1.02437) | 0.842 |
| NOx, ppb | 1.00069 (0.99525 - 1.00615) | 0.804 | 1.00145 (0.98931 - 1.01374) | 0.815 |
| PM10, µg/m3 | 1.00004 (0.99842 - 1.00166) | 0.958 | 1.00007 (0.99832 - 1.00182) | 0.934 |
The Results of Negative Binomial Regression of the Impact of Air Pollutants on Overall Daily Deaths in the Elderly (Men and Women) Caused by Other Diseases (Ratio of Increased Daily Mortality for Every Unit Increase in Average Daily Emissions)
| Pollutant | Crude IRR and 95%CI | P-Value | Adjusted IRR and 95%CI | P-Value |
|---|---|---|---|---|
| Total | ||||
| CO, ppm | 0.92516 (0.87798 - 0.97488) | 0.004a | 0.90067 (0.83224 - 0.97473) | 0.009a |
| SO2, ppb | 1.00602 (0.99180 - 1.02044) | 0.499 | 1.00401 (0.99366 - 1.014469) | 0.499 |
| O3, ppb | 1.00373 (1.00156 - 1.00591) | 0.001a | 1.00361 (1.00064 - 1.00658) | 0.017a |
| NO, ppb | 1.00263 (1.00006 - 1.00521) | 0.048a | 1.00257 (0.99664 - 1.00852) | 0.396 |
| NO2, ppb | 0.99281 (0.98772 – 0.99793) | 0.006a | 0.99813 (0.98852 - 1.00783) | 0.705 |
| NOx, ppb | 1.00225 (0.99815 - 1.00636) | 0.646 | 1.00232 (0.99646 - 1.00821) | 0.438 |
| PM10, µg/m3 | 1.00015 (0.99891 - 1.00140) | 0.300 | 1.00011 (0.99935 - 1.00087) | 0.769 |
| Men | ||||
| CO, ppm | 0.95237 (0.89012 - 1.01897) | 0.157 | 0.96411 (0.86908 - 1.06953) | 0.490 |
| SO2, ppb | 1.00280 (0.99266 - 1.011224) | 0.688 | 1.00592 (0.99229 - 1.01973) | 0.396 |
| O3, ppb | 1.00280 (0.99986 - 1.00575) | 0.061 | 1.00243 (0.99840 - 1.00646) | 0.237 |
| NO, ppb | 1.00147 (0.99805 - 1.00490) | 0.399 | 1.00295 (0.99420 - 1.01178) | 0.509 |
| NO2, ppb | 0.99439 (0.98767 - 1.00116) | 0.105 | 0.99895 (0.98548 - 1.01261) | 0.880 |
| NOx, ppb | 0.99969 (0.99673 - 1.00267) | 0.842 | 0.99833 (0.98963 - 1.00711) | 0.709 |
| PM10, µg/m3 | 0.99954 (0.99861 - 1.00046 | 0.329 | 0.99969 (0.99868 - 1.00071) | 0.558 |
| Women | ||||
| CO, ppm | 0.944729 (0.87199 - 1.02353) | 0.164 | 0.95721 (0.84999 - 1.07796) | 0.471 |
| SO2, ppb | 0.99669 (0.98410 - 1.00944) | 0.609 | 0.99577 (0.97993 - 1.01187) | 0.605 |
| O3, ppb | 1.00391 (1.00061 - 1.00722) | 0.020a | 1.00446 (0.99996 - 1.00898) | 0.052 |
| NO, ppb | 1.00002 (0.99617 - 1.00387) | 0.991 | 0.99952 (0.99094–1.00818) | 0.914 |
| NO2, ppb | 0.99469 (0.98700 - 1.00245) | 0.180 | 0.99727 (0.98320 - 1.01154) | 0.707 |
| NOx, ppb | 0.99934 (0.99600 - 1.00270) | 0.703 | 1.00331 (0.99492 - 1.01177) | 0.440 |
| PM10, µg/m3 | 0.99993 (0.99889 - 1.00096) | 0.897 | 1.00061 (0.99949 - 1.00174) | 0.281 |
The results of multivariate analysis indicated that CO was directly related to cardiovascular death of the elderly, but this relation disappeared in the gender subgroups, probably because the population size decreased (Table 4). Air pollutants did not show any significant effect on respiratory- (Table 5), trauma- (Table 6), and diabetes- (Table 7) related deaths in the elderly of Kerman city. The results of multivariate analysis of air pollutants indicated that ozone played a significant role in increasing the death of the elderly who died from other diseases (Table 8).
5. Discussion
This study aimed to investigate the relation between air pollutants and the number of elderly deaths in one of the major Iranian cities. The results indicated that CO played a significant role in the cardiovascular deaths of the elderly. Indeed, CO triggers complex pro-inflammatory phenomena in the airways and combines with blood hemoglobin, and forms a stable hybrid, which is carboxyhemoglobin, thereby causing hypoxia and heart failure. Moreover, it affects the central nervous system and eventually, can lead to death (11). Studies conducted in Taiwan also showed a relation between CO and cardiac mortality, especially in the elderly and in the winter (12). Another study conducted on British individuals aged over 45 years, also found a significant relation between CO and cardiovascular deaths (13). In Tehran, studies found that the most important effect of CO was on the cardiovascular system and increase in cardiovascular deaths (14), and there was a significant relation between CO and the daily number of deaths among people aged over 64 years in Tehran (15). The present study also showed that CO could probably affect deaths among the elderly. However, we found no significant relation between CO and deaths caused by respiratory diseases, trauma, or diabetes in the elderly.
In this study, there was a relation between NO and total deaths in the elderly, especially women. However, the results of this study did not show a significant impact of nitrogen oxides on deaths caused by cardiovascular diseases, respiratory diseases, trauma, diabetes, or other diseases in the elderly. The results of a study on people aged 50 - 64 years in Denmark showed no significant relation between nitrogen dioxide (NO2) and deaths caused by cardiac diseases, including myocardial infarction, angina pectoris, high blood pressure, and stroke and diabetes (16). However, the results of a study from Canada on people with an average age of 60 indicated a relation between all causes of death and NO2 (17). Wong in China also showed a relation between NO2 and deaths caused by cardiac diseases among hospital-admitted patients (18). Given the aforementioned controversies and inconsistencies, it seems that NO2 and its association with mortality require further investigation.
The results of this study showed that SO2 did not have a significant impact on deaths caused by respiratory diseases, trauma, and diabetes, as well as other diseases in the elderly. However, there was a significant relation between SO2 and all deaths among elderly women. Interestingly, the aforementioned issue was not seen in elderly men. In a study conducted in Kerman, Iran increased SO2 was significantly related to respiratory deaths in men (19) and was also associated with increased respiratory hospital admissions among women (20). However, in a study conducted in Beijing long-term exposure to SO2 was not related to respiratory deaths (21). Similarly, in another study from Taiwan, there was no relation between SO2 and respiratory deaths (12), and in Spain, there was no relation between SO2 concentration and patients admitted to hospitals due to asthma attacks (22) either. This lack of relation was also reported in another study conducted in New York (23).
In the present study, there was a significant relation between ozone and total deaths in elderly women as well as total deaths caused by other diseases. However, the results of multivariate analysis indicated that ozone did not significantly correlate with elderly deaths caused by cardiovascular and respiratory diseases as well as trauma and diabetes. Another study from China indicated that there was no significant relation between ozone and deaths caused by respiratory diseases (18) either. Also, ozone concentration was not related to asthma attacks in Spain (22). In contrast, ozone was related to respiratory deaths in men in Kerman (24).
Apparently, PM10 did not increase the death of elderly people in Kerman, Therefore, more research should be conducted in this regard. Several mechanisms have been proposed about how PM may impact death, including pneumonia, exacerbation of atherosclerosis, changes in heart function, inflammation of the air sacs, aggravation of lung diseases, increased blood clotting, increased blood viscosity, increased plasma fibrinogen, and changes in heartbeat (25).
However, it seems that further studies are still needed to determine the mechanism of its action. Inhalation of PM can cause oxidative stress and inflammatory responses in the lungs (26). Also, PM can penetrate into the lungs in the form of dust. Besides, they may pass through the lungs and enter blood circulation and reach other organs (27). In studies conducted in Taiwan, increased systolic and diastolic blood pressure was associated with increased annual average levels of PM2.5 and PM10 (28). In another study conducted in China, a relation was seen between PM10 and the number of overall deaths, and the impact was more severe on people aged 45 to 65 years than younger people (25). Conversely, another study conducted in Taiwan found no significant relation between PM10 and respiratory deaths (12). Furthermore, a significant relation was seen between short-term changes in deaths and PM10 and PM2.5 in several US cities (29). In a previous study in Kerman, PM10 significantly increased respiratory mortality among men (24).
Epidemiological studies conducted over the past two decades around the world have shown that the effects of air pollution on human health and deaths associated with air pollution are on the rise (30).
Kerman City encounters sand storms in the spring and autumn (31). Also, several stone, sand, and gravel crushing plants, as well as asphalt plants, operate around the city, which contribute to this city’s air pollution. Therefore, it seems essential to pay particular attention to vulnerable groups, particularly the elderly on days with high air pollution. Suitable planning such as reducing elders’ commuting time on high air pollution days can help prevent mortality. Table 9 presents the results of several studies conducted in various regions around the world about the effect of air pollution on mortality in the elderly. Similar to the findings of our study, some other studies also suggest that air pollution can contribute to increased cardiovascular and respiratory mortality in the elderly.
A Summary of Studies Conducted in Various Regions Around the World on the Effect of Air Pollution on Mortality in the Elderly
| ID | Year | Country/Region | Results |
|---|---|---|---|
| Fischer et al. (32) | 2003 | Netherlands | The study showed that the pollutants PM10, BS, and SO2, NO2 and CO increase the risk of mortality, especially in the elderly (individuals with 65 - 74 and higher than or equal to75 years of age). |
| Daumas et al. (33) | 2004 | Brazil | The study showed that an increase in total suspended particles (TSP) levels from the 10th to the 90th percentile (104.7 µg/m3) increase the risk for mortality in elderly people from cardiovascular and respiratory diseases. |
| Filleul et al. (34) | 2004 | Bordeaux | The study showed that an increase of 10 mug/m3 of black smoke increased the risk of cardiorespiratory mortality among the elderly (odds ratio = 1.30, 95% CI: 1.01 - 1.68). |
| Enstrom (35) | 2005 | California | The study showed that for the initial period, 1973 - 1982, a 10-mu g/m3 increase in PM2.5 increased risk of mortality in the elderly RR (1.04, 1.01 - 1.07). However, this risk was no longer present for the subsequent period, 1983 - 2002. The findings presents no current relation between fine particulate pollution and total mortality in elderly Californians, but they do not rule out a small effect, particularly before 1983. |
| Cakmak et al. (36) | 2007 | Chile | The study shows that for elderly above the age of 85 years, the percentage increases in non - accidental mortality associated with an increase in PM10 equivalent to its mean was 14.03 (3.87), for O3 8.56 (2.02), for SO2 7.92 (3.23); and for CO 8.58 (4.45). Results suggested that the very elderly are particularly vulnerable to dying from air pollution. |
| Halonen et al. (37) | 2009 | Finland | The study indicated an association of hospital admissions for arrhythmia with Aitken mode particles and PM2.5 from traffic. There were also positive associations between most particle fractions with admissions for pneumonia and asthma - chronic obstructive pulmonary disease (COPD). All particle fractions namely Aitken, accumulation, and coarse mode caused adverse respiratory health effects in the elderly. Generally, associations were stronger for respiratory compared to cardiovascular consequences. |
| Jimenez et al. (38) | 2011 | Madrid (Spain) | The study indicated that in the elderly coarser PM fractions (PM10 and PM10-2.5) is associated with respiratory - specific mortality, and PM2.5 is related to cardiovascular - specific mortality. In addition, compared to winter, the risk of mortality due to exposure to particulate matter was greater in summer. |
| Krstic (39) | 2011 | Vancouver | Findings showed a very weak negative association between air pollution and the elderly’s mortality. |
| Goldberg et al. (8) | 2013 | Montreal, Quebec | The study found that daily non-accidental mortality among the elderly is positively associated with all air pollutants except ozone, especially amongst elderly persons having cardiovascular diseases, congestive heart failure, and diabetes. It was also suggested that individuals with certain health conditions, especially those with diabetes and cardiovascular diseases, hypertension, atrial fibrillation, and cancer, might be vulnerable to the short-term effects of air pollution. |
| Vanos et al. (40) | 2013 | Canada | The study revealed that weather type had the greatest modifying effect on the risk of dying due to ozone in the entire elderly population. This effect was the highest on average for the dry tropical (DT) weather type. All-weather type risk estimates increased with age due to exposure to carbon monoxide (CO), nitrogen dioxide (NO2), and Sulphur dioxide (SO2). For all weather types increased levels of air pollution were found to have adverse health effects for elderly individuals. Air pollution on the hot dry (DT) and hot humid (MT) days had negatively affected the entire population. |
| Yang et al. (6) | 2018 | Hong Kong | The study revealed that long - term exposure to ambient PM2.5 and black carbon (BC) caused an elevated risk of cardiovascular mortality in elderly with the age of equal and greater than 65. |
| Yap et al. (7) | 2019 | Singapore | The study indicated that in single - day lag models, every 10 µg/m3 rise in particulate matter increases non - accidental and cardiovascular mortality in the elderly. This was significant in the elderly ≥ 65 years and were seen in the acute phase of lag 0 - 5 days. |
| Dalecka et al. (41) | 2021 | Germany | The study revealed that after adjusting for reduced lung function and additional covariates, long - term exposures to NOx and NO2 were associated with increased risks of cardio - pulmonary mortality (CPM) among elderly women. The mediation analysis showed significant indirect effects of NO2 and NOx on CPM mediated through reduced FEV1 and FVC. The largest indirect effects were found for exposures to NO2 and NOx mediated through reduced FVC. |
5.1. Conclusions
It seems among the elderly, cardiovascular diseases are more vulnerable to air pollution than others. Carbon monoxide, nitrogen oxide, and sulfur dioxide may play an important role in elderly deaths. A warning system to reduce elders’ commuting on high air pollution days is suggested.
Acknowledgements
References
-
1.
Masjedi MR, Jamaati HR, Dokouhaki P, Ahmadzadeh Z, Taheri SA, Bigdeli M, et al. The effects of air pollution on acute respiratory conditions. Respirology. 2003;8(2):213-30. [PubMed ID: 12753539]. https://doi.org/10.1046/j.1440-1843.2003.00455.x.
-
2.
Hashemi SY. Air pollution and cardiovascular hospital admissions in Kerman, Iran. Journal of Heart and Cardiology. 2016;2(2):1-6. https://doi.org/10.15436/2378-6914.16.018.
-
3.
Dadbakhsh M, Khanjani N, Bahrampour A. Death from respiratory diseases and air pollutants in Shiraz, Iran (2006-2012). J Environ Pollut Hum Health. 2015;3(1):4-11.
-
4.
Bernstein JA, Alexis N, Bacchus H, Bernstein IL, Fritz P, Horner E, et al. The health effects of non-industrial indoor air pollution. J Allergy Clin Immunol. 2008;121(3):585-91. [PubMed ID: 18155285]. https://doi.org/10.1016/j.jaci.2007.10.045.
-
5.
Santus P, Russo A, Madonini E, Allegra L, Blasi F, Centanni S, et al. How air pollution influences clinical management of respiratory diseases. A case-crossover study in Milan. Respir Res. 2012;13:95. [PubMed ID: 23078274]. [PubMed Central ID: PMC3511062]. https://doi.org/10.1186/1465-9921-13-95.
-
6.
Yang Y, Tang R, Qiu H, Lai PC, Wong P, Thach TQ, et al. Long term exposure to air pollution and mortality in an elderly cohort in Hong Kong. Environ Int. 2018;117:99-106. [PubMed ID: 29730535]. https://doi.org/10.1016/j.envint.2018.04.034.
-
7.
Yap J, Ng Y, Yeo KK, Sahlen A, Lam CSP, Lee V, et al. Particulate air pollution on cardiovascular mortality in the tropics: impact on the elderly. Environ Health. 2019;18(1):34. [PubMed ID: 30999903]. [PubMed Central ID: PMC6471752]. https://doi.org/10.1186/s12940-019-0476-4.
-
8.
Goldberg MS, Burnett RT, Stieb DM, Brophy JM, Daskalopoulou SS, Valois MF, et al. Associations between ambient air pollution and daily mortality among elderly persons in Montreal, Quebec. Sci Total Environ. 2013;463-464:931-42. [PubMed ID: 23872247]. https://doi.org/10.1016/j.scitotenv.2013.06.095.
-
9.
The Statistical Center of Iran. Census 2012. 2012. Available from: http://www.amar.org.ir.
-
10.
Dehghan A, Khanjani N, Bahrampour A, Goudarzi G, Yunesian M, Hopke PK, et al. Forecasting Ambient Air Pollutants in Tehran, Iran. Environ Justice. 2020;13(6):193-201. https://doi.org/10.1089/env.2020.0015.
-
11.
Ghio AJ, Smith CB, Madden MC. Diesel exhaust particles and airway inflammation. Curr Opin Pulm Med. 2012;18(2):144-50. [PubMed ID: 22234273]. https://doi.org/10.1097/MCP.0b013e32834f0e2a.
-
12.
Liang WM, Wei HY, Kuo HW. Association between daily mortality from respiratory and cardiovascular diseases and air pollution in Taiwan. Environ Res. 2009;109(1):51-8. [PubMed ID: 19027107]. https://doi.org/10.1016/j.envres.2008.10.002.
-
13.
Maheswaran R, Haining RP, Brindley P, Law J, Pearson T, Fryers PR, et al. Outdoor air pollution, mortality, and hospital admissions from coronary heart disease in Sheffield, UK: a small-area level ecological study. Eur Heart J. 2005;26(23):2543-9. [PubMed ID: 16166102]. https://doi.org/10.1093/eurheartj/ehi457.
-
14.
Gholizadeh MH, Farajzadeh M, Darand M. The correlation between air pollution and human mortality in Tehran. Hakim Res J. 2009;12(2):65-71.
-
15.
Younesian M, Maek A, Holakouei NK. Air pollution mortality in elderly in Tehran, Iran. Payesh. 2002;1(1):19-24.
-
16.
Raaschou-Nielsen O, Andersen ZJ, Hvidberg M, Jensen SS, Ketzel M, Sorensen M, et al. Lung cancer incidence and long-term exposure to air pollution from traffic. Environ Health Perspect. 2011;119(6):860-5. [PubMed ID: 21227886]. [PubMed Central ID: PMC3114823]. https://doi.org/10.1289/ehp.1002353.
-
17.
Jerrett M, Finkelstein MM, Brook JR, Arain MA, Kanaroglou P, Stieb DM, et al. A cohort study of traffic-related air pollution and mortality in Toronto, Ontario, Canada. Environ Health Perspect. 2009;117(5):772-7. [PubMed ID: 19479020]. [PubMed Central ID: PMC2685840]. https://doi.org/10.1289/ehp.11533.
-
18.
Wong TW, Tam WS, Yu TS, Wong AH. Associations between daily mortalities from respiratory and cardiovascular diseases and air pollution in Hong Kong, China. Occup Environ Med. 2002;59(1):30-5. [PubMed ID: 11836466]. [PubMed Central ID: PMC1740206]. https://doi.org/10.1136/oem.59.1.30.
-
19.
Dastoorpoor M, Idani E, Khanjani N, Goudarzi G, Bahrampour A. Relationship Between Air Pollution, Weather, Traffic, and Traffic-Related Mortality. Trauma Mon. 2016;21(4). e37585. [PubMed ID: 28180125]. [PubMed Central ID: PMC5282930]. https://doi.org/10.5812/traumamon.37585.
-
20.
Rezaei S, Khanjani N, Mohammadi Senjedkooh S, Darabi Fard Z. The effect of air pollution on respiratory disease visits to the emergency department in Kerman, Iran. Health Develop J. 2020;4(4):306-14.
-
21.
Zhang J, Song H, Tong S, Li L, Liu B, Wan L. Ambient sulfate concentration and chronic disease mortality in Beijing. Sci Total Environ. 2000;262(1-2):63-71. [PubMed ID: 11059843]. https://doi.org/10.1016/s0048-9697(00)00573-8.
-
22.
Dadbakhsh M, Khanjani N, Bahrampour A. The relation between mortality from cardiovascular diseases and temperature in Shiraz, Iran, 2006-2012. ARYA Atheroscler. 2018;14(4):149-56. [PubMed ID: 30627190]. [PubMed Central ID: PMC6312568]. https://doi.org/10.22122/arya.v14i4.1341.
-
23.
Khanjani* N, Hashemi SY. Air Pollution and Cardiovascular Mortality in Kerman, Iran; from 2006 to 2011. ISEE Conf Abstr. 2014;2014(1). https://doi.org/10.1289/isee.2014.P2-502.
-
24.
Khanjani N, Mansouri F. Air pollution and respiratory deaths in Kerman, Iran (from 2006 till 2010). Iran J Epidemiol. 2012;8(3):58-65.
-
25.
Qian Z, He Q, Lin HM, Kong L, Liao D, Dan J, et al. Association of daily cause-specific mortality with ambient particle air pollution in Wuhan, China. Environ Res. 2007;105(3):380-9. [PubMed ID: 17604019]. https://doi.org/10.1016/j.envres.2007.05.007.
-
26.
Brook RD, Franklin B, Cascio W, Hong Y, Howard G, Lipsett M, et al. Air pollution and cardiovascular disease: a statement for healthcare professionals from the Expert Panel on Population and Prevention Science of the American Heart Association. Circulation. 2004;109(21):2655-71. [PubMed ID: 15173049]. https://doi.org/10.1161/01.CIR.0000128587.30041.C8.
-
27.
Nemmar A, Hoet PH, Vanquickenborne B, Dinsdale D, Thomeer M, Hoylaerts MF, et al. Passage of inhaled particles into the blood circulation in humans. Circulation. 2002;105(4):411-4. [PubMed ID: 11815420]. https://doi.org/10.1161/hc0402.104118.
-
28.
Chuang KJ, Yan YH, Chiu SY, Cheng TJ. Long-term air pollution exposure and risk factors for cardiovascular diseases among the elderly in Taiwan. Occup Environ Med. 2011;68(1):64-8. [PubMed ID: 20833756]. https://doi.org/10.1136/oem.2009.052704.
-
29.
Schwartz J. Air pollution and daily mortality in Birmingham, Alabama. Am J Epidemiol. 1993;137(10):1136-47. [PubMed ID: 8317443]. https://doi.org/10.1093/oxfordjournals.aje.a116617.
-
30.
Krzyzanowski M, Cohen A, Anderson R, W. H. O. Working Group. Quantification of health effects of exposure to air pollution. Occup Environ Med. 2002;59(12):791-3. [PubMed ID: 12468743]. [PubMed Central ID: PMC1763610]. https://doi.org/10.1136/oem.59.12.791.
-
31.
Mansouri F, Khanjani N, Pourmousa R. Forecasting ambient air pollutants by time series models in Kerman, Iran. J Sch Public Health Inst Public Health Res. 2013;11(2):75-86.
-
32.
Fischer P, Hoek G, Brunekreef B, Verhoeff A, van Wijnen J. Air pollution and mortality in The Netherlands: are the elderly more at risk? Eur Respir J Suppl. 2003;40:34s-8s. [PubMed ID: 12762572]. https://doi.org/10.1183/09031936.03.00402503.
-
33.
Daumas RP, Mendonca GA, Ponce de Leon A. [Air pollution and mortality in the elderly in Rio de Janeiro: a time-series analysis]. Cad Saude Publica. 2004;20(1):311-9. [PubMed ID: 15029334]. https://doi.org/10.1590/s0102-311x2004000100049.
-
34.
Filleul L, Rondeau V, Cantagrel A, Dartigues JF, Tessier JF. Do subject characteristics modify the effects of particulate air pollution on daily mortality among the elderly? J Occup Environ Med. 2004;46(11):1115-22. [PubMed ID: 15534498]. https://doi.org/10.1097/01.jom.0000144998.82543.9d.
-
35.
Enstrom JE. Fine particulate air pollution and total mortality among elderly Californians, 1973-2002. Inhal Toxicol. 2005;17(14):803-16. [PubMed ID: 16282158]. https://doi.org/10.1080/08958370500240413.
-
36.
Cakmak S, Dales RE, Vidal CB. Air pollution and mortality in Chile: susceptibility among the elderly. Environ Health Perspect. 2007;115(4):524-7. [PubMed ID: 17450219]. [PubMed Central ID: PMC1852651]. https://doi.org/10.1289/ehp.9567.
-
37.
Halonen JI, Lanki T, Yli-Tuomi T, Tiittanen P, Kulmala M, Pekkanen J. Particulate air pollution and acute cardiorespiratory hospital admissions and mortality among the elderly. Epidemiology. 2009;20(1):143-53. [PubMed ID: 19234403]. https://doi.org/10.1097/EDE.0b013e31818c7237.
-
38.
Jimenez E, Linares C, Martinez D, Diaz J. Particulate air pollution and short-term mortality due to specific causes among the elderly in Madrid (Spain): seasonal differences. Int J Environ Health Res. 2011;21(5):372-90. [PubMed ID: 21547809]. https://doi.org/10.1080/09603123.2011.560251.
-
39.
Krstic G. Apparent temperature and air pollution vs. elderly population mortality in Metro Vancouver. PLoS One. 2011;6(9). e25101. [PubMed ID: 21980381]. [PubMed Central ID: PMC3182192]. https://doi.org/10.1371/journal.pone.0025101.
-
40.
Vanos JK, Cakmak S, Bristow C, Brion V, Tremblay N, Martin SL, et al. Synoptic weather typing applied to air pollution mortality among the elderly in 10 Canadian cities. Environ Res. 2013;126:66-75. https://doi.org/10.1016/j.envres.2013.08.003.
-
41.
Dalecka A, Wigmann C, Kress S, Altug H, Jirik V, Heinrich J, et al. The mediating role of lung function on air pollution-induced cardiopulmonary mortality in elderly women: The SALIA cohort study with 22-year mortality follow-up. Int J Hyg Environ Health. 2021;233:113705. [PubMed ID: 33582605]. https://doi.org/10.1016/j.ijheh.2021.113705.