Chronic Obstructive Pulmonary Disease and Lung Cancer Mortality Attributed to Air Pollution in Türkiye in 2019

Received: June 20, 2023
Revised: August 19, 2023
Accepted: August 24, 2023

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Cite this article:

Han Yekdeş, D., Yekdeş, A.C., Çelikkalp, Ü., Sarı Serin, P., Çağlayan, M., Ekuklu, G. (2023). Chronic Obstructive Pulmonary Disease and Lung Cancer Mortality Attributed to Air Pollution in Turkey in 2019. Aerosol Air Qual. Res. 23, 230144. https://doi.org/10.4209/aaqr.230144

HIGHLIGHTS

• The annual average value of PM_2.5 for 2019 in Türkiye was 28.82 (µg m^–3).
• The mortality rate attributed to PM_2.5 for lung cancer is 15%.
• The mortality rate attributed to PM_2.5 for COPD is 22%.
• There is no treshold limit in the legislation in Türkiye for PM_2.5 levels.
• Taking precautions to control air pollution sources should be prioritized.

Keywords: Air pollution, PM2.5, Health effects/risks, Regional air quality

1 INTRODUCTION

Air pollution is defined as the contamination of the atmosphere via physical, chemical, or biological agent. It can occur both naturally, such as during volcanic eruptions and dust storms or as a result of anthropogenic activity such as providing energy for heating, transportation, and industrial purposes from fossil fuels (WHO, 2022a).

Both nationally and internationally, 90% of the total population breathes polluted air. According to the data provided by World Health Organization (WHO), 4.2 million deaths per year are attributed to outdoor air pollution and 3.2 million deaths per year to indoor air pollution (Landrigan, 2017). Diseases that can develop with prolonged exposure to Particulate Matter 2.5 (PM_2.5) can be exemplified as chronic obstructive pulmonary disease (COPD), stroke, ischemic heart disease, and lung cancer. There is also literature reporting findings about the relationship between air pollution with low birth weight, diabetes, and neurological events (Kampa and Castanas, 2008; Wei et al., 2022).

Air pollution can cause not only health-related problems but also environmental problems that indirectly affect the majority of the global population in terms of climate change (Kinney, 2008). The International Agency for Research on Cancer (IARC) classified outdoor air pollution and PM_2.5 as definite carcinogens in 2013 and proved their relationship with lung cancer. In particular, polycyclic aromatic hydrocarbons and benzoapyrenes contained in PM shown to increase the risk of developing cancer (Loomis et al., 2013).

In the context of combating air pollution in Türkiye, the levels of pollutants are monitored through air quality measurement stations. However, the limit values for these pollutants are considerably higher than the established standards set by the World Health Organization (WHO) and the European Union (EU). Additionally, there is an absence of a specific regulatory limit for PM_2.5 in the country's legislation. Furthermore, the representation of regions through the number of monitoring stations is hindered by certain challenges, and it should be noted that PM_2.5 measurements are not available at all stations (RtCAP, 2021).

Our study represents the first research endeavor in the country to calculate cause-specific mortality attributed to air pollution, alongside a previous investigation that estimated PM_2.5-related deaths (Pala et al., 2021).

Disease and mortality data related to air pollution can provide useful resources for academics, policymakers, and governments so that protective measures can be taken to make political arrangements in this regard. The aim of the study is to examine the changes in PM_2.5 concentrations in Türkiye in the year 2019 as well as to calculate the mortality rates of lung cancer and COPD that can be attributed to long-term exposure to PM_2.5 with the use of World Health Organization (WHO) AIRQ+ program.

 
2 METHODS

Our research is in ecological design in which PM_2.5 and PM₁₀ data for the year 2019 and province-based COPD and lung cancer mortality data in Türkiye for the given period is evaluated retrospectively. AirQ+ 2.2 software was used to calculate mortality rates attributed to air pollution.

 
2.1 Data Collection Tools

2.1.1 Demographics and mortality data

The total population of Türkiye in 2019 was calculated to be 83,154,997. To determine the population at risk, the data from Turkish Statistical Institute (TURKSTAT) by age groups was used, and the 0–25 age group was excluded from the total population for each province. The total population at risk (25 years and older) was calculated to be 50,986,980 (TURKSTAT, 2019). In Türkiye, in the year 2019, province-based COPD and lung cancer-related mortality data were not readily accessible on the official website of TURKSTAT, thus for our research, Lung Cancer and COPD International Classification of Diseases (ICD) codes were obtained by special request. Death data were collected in the form of annual mortality counts at the province level, and utilizing population-at-risk data, they were transformed into mortality rates using the AirQ+ software.

 
2.1.2 Air pollutant data

Information about the concentrations of PM_2.5 and PM₁₀ for Türkiye for the year 2019 (01.01.2019–31.12.2019), were obtained in the form of daily values from the official website of the Ministry of Environment, Urbanization, and Climate Change since there was no other air pollutant-related literature can be found through out the research (MoEUCC, 2019). For air quality-research stations where PM_2.5 data was not available, PM₁₀ values were used after being converted into PM_2.5 via multiplicating with 0.65 coefficient (21% of the PM_2.5 data was derived by converting from PM₁₀ values) (WHO, 2022a). The inclusion criteria for our study for each station of every province was having 50 percent or more measurements data of PM₁₀ and PM_2.5 at the given time.

The data of the year 2019 in mortality calculations attributed to air pollution in Türkiye is used as there was a delay on publication of 2020 mortality data, which later published in 2023. Thus, the latest available data was from the year 2019 and had been used in the research.

 
2.2 Statistical Analysis

In our study, cause-specific mortality rates attributed to air pollution were computed. The dependent variables of the study are the mortality rates of COPD and the mortality rates of lung cancer, and the main predictor is the annual mean PM_2.5 values of each province. Descriptive statistics include the mean values of both PM₁₀ and PM_2.5, while only PM_2.5 data was employed for cause-specific mortality calculations. The calculation of mortality rates of lung cancer and COPD attributed to PM_2.5 was performed with AIR Q+ v.2.2 software. The AIR Q+ program, which is developed by the WHO European Region, provides information about pollutant-specific acute and chronic health problems. AirQ+ use the pollutants (PM_2.5, PM₁₀, NO₂, O₃, and black carbon (BC)) as an input data and calculate their long- and short-term effects. Short-term effects include hospital admissions and work-day losses whereas long-term effects include mortality from all-causes or specific-causes (lung cancer mortality, COPD mortality, etc.). The working principle of the AirQ+ program is derived from the dose-response relationship of health effects related to air pollution, as evidenced by epidemiological studies including systematic reviews and meta-analyses (Mudu et al., 2018; Hoek et al., 2013). The calculations require air quality data (annual mean PM_2.5 concentration), population-at-risk (ages 25+), and cause-specific mortality rates of the population-at-risk (WHO, 2022a). The program calculates PM_2.5-attributed COPD and lung cancer mortality rates for each province and presents them as statistical regional unit averages. In these calculations, relative risk values are not included as the integrated risk function is used instead (WHO, 2022a). In our study the mortality rates of COPD and lung cancer attributed to PM_2.5 were calculated for each province and presented as the average of NUTS region with this program.

The changes in the monthly PM₁₀ level of each NUTS region were evaluated with the Joinpoint Regression Program version 4.9.1.0 (National Cancer Institute; http://surveillance.cancer.gov/​joinpoint). The Joint Point regression method is a trend analysis technique that aids in identifying significant breakpoints in the trend. Monthly averages were calculated for this purpose. Monthly Changes in PM₁₀ trends were evaluated for each NUTS region using the Joinpoint modelizations were evaluated by permutation method. Trends were described by the monthly percent change (MPC) for each segment, and by the average MPC (AMPC) for the whole period throughout 2019. A p-value < 0.05 was used to determine if the MPC and AMPC were significantly different from zero.

Ethical permission for the research was obtained by the Trakya University Faculty of Medicine, Non-Interventional Scientific Research Ethics Committee (dated November 14, 2022, decision number 22/20, and number 2022/376).

 
3 RESULTS

It was originally planned to evaluate the PM_2.5 and PM₁₀ concentrations of all 81 provinces of Türkiye, but since there was no PM₁₀ and PM_2.5 data measurement for the province Uşak, the data of the 80 provinces (180 station regions) were evaluated in the course of time. The average pollutant values in Türkiye for the year 2019 are presented in Fig. 1. According to this, the national annual average values for PM_2.5 and PM₁₀ are measured to be 28.8 µg m^–3 and 48.08 µg m^–3, respectively. The region with the highest annual average values of both pollutants is shown to be northeast Anatolia. The region with the lowest annual average value for PM_2.5 is the Western Marmara region.

Fig. 1. Annual average PM_2.5 and PM₁₀ values (µg m^–3) for 2019 according to Nomenclature d'Unités Territoriales Statistiques (NUTS) classification in Türkiye.

When the province-based annual average PM_2.5 concentrations were evaluated for Türkiye, the three highly affected provinces were determined to be Muş (88.65 µg m^–3), Igdır (55.9 µg m^–3), and Agrı (54 µg m^–3), respectively. On the other hand, the three provinces with the lowest average values were shown to be Yozgat (13.08 µg m^–3), Yalova (16.35 µg m^–3), and Tekirdag (20.19 µg m^–3) respectively.

The monthly change in PM₁₀ levels for each NUTS regions was analyzed by JP regression programme (Fig. 2). Except for 2 NUTS region (TR1 and TR7 regions) all other regions have 1 statistically significant joinpoint. For TRA-TRB-TRC regions joinpoint locations observed in July and August, whereas for TR2-3-4-5-6-8-9 regions the jointpoint found in April-May. Besides, the annual average monthly percent change (AMPC) was not found statistically significant in all regions.

Fig. 2. Changes in 2019 PM₁₀ levels (µg m^–3) in Nomenclature d'Unités Territoriales Statistiques (NUTS) regions of Türkiye by months.

In Türkiye in the year 2019, for the people aged 25 and older, 24,187 total deaths were attributed to lung cancer whereas 23,224 deaths were attributed to COPD. The COPD and lung cancer mortality rate attributed to PM_2.5 is presented in Table 1 and attributed proportion to PM_2.5 is presented in Fig. 3. Accordingly, the three regions with the highest percentage of lung cancer mortality related to PM_2.5 are Istanbul (21%), Northeast Anatolia (18.55%), and Southeast Anatolia (17.01%). The three regions with the highest percentage of COPD mortality related to PM_2.5 are Northeast Anatolia (25.3%), Southeastern Anatolia (23.89%), and Western Black Sea (22.9%). Furthermore, mortality rates attributed to province-based PM_2.5 have also been presented in supplementary tables (Table 2 and Table 3).

Fig. 3. Lung Cancer and COPD Mortality Rate Attributed Proportion to PM_2.5 for 2019 in Türkiye.

4 DISCUSSION

Air pollution is a global problem particularly affecting the developing countries ever since the 19th century second half, where industrialization innovation took place and the fossil fuel usage became a preferred option for energy generation (Ab Manan et al., 2018).

Air pollutants, chiefly those with a diameter of 2.5 µm and smaller (PM_2.5), cause cardiovascular and respiratory system diseases and cancers. In this study lung cancer mortality rates and COPD mortality rates due to air pollution in Türkiye were reviewed.

The PM₁₀ value of Türkiye for the year 2019 is about 50 µg m^–3 which is considerably higher than the WHO (20 µg m^–3) and European Union (EU) (40 µg m^–3) annual limit values. The annual limit value is 40 µg m^–3 for PM₁₀ in Türkiye, but there is no guideline limit value for PM_2.5. The annual average PM_2.5 level calculated across the country is approximately 30 µg m^–3. This value is likewise higher than the 2019 WHO (10 µg m^–3) and EU (25 µg m^–3) limit values (Fig. 1).

When the change in the trend throughout the year is examined, it is detected that there is a decrease in the pollutant level for the summer season whereas the levels reach their peak in the winter season (Fig. 2). The region with the lowest average value in terms of PM₁₀ pollution is observed to be the Eastern Black Sea region, whilst the regions with the highest average values are observed to be Northeast Anatolia Region. In the course of examining the results, it is detected that some provinces has considerably high values such as Mus, scoring a 88.65 µg m^–3, which is approximately eight times higher than the WHO limit value. This results has been described before (İnandi et al., 2018). They examined air pollution's trend in Türkiye and stated that the pollutant levels are following a decreasing trend. They also concluded an interregional difference in pollutant levels, which matches the findings of our own study. The reason for the regional differences is thought to be a result of having a different level of domestic heating, vehicles, and industrial emission and having a rapid and unplanned urbanization in some of the regions in recent years (RtCAP, 2021). It is thought that factors such as the poor quality of the coal used in fossil fuel consumption, the lack of rail public transportation systems in almost all of the cities, the excessive number of vehicles in transportation, and the negative impact of wrong construction have on the region's wind circulation had an impact on the pollutant levels. In addition, for the southern regions of the country, dust clouds coming from Africa can be another cause of the PM pollution (Pey et al., 2013).

Global burden of disease studies indicate that air pollution is one of the two primary environmental risk factors for well-being; the other being the issue of unsafe water (Varol et al., 2021). While the health effects of air pollution occur in conjunction with exposure, there is no given threshold level at which a health effect will not occur (Liu et al., 2019). According to a meta-analysis study which examined respiratory-related hospitalizations, increase in PM₁₀ levels were associated with a 0.1–1.3% increase in hospitalizations (Ab Manan et al., 2018). A 2019 study involving approximately 60 million deaths concluded that an increase of 10 µg m^–3 was associated with a 0.44% increase in daily all-cause mortality (Liu et al., 2019). In a study in which deaths attributed to PM_2.5 in Türkiye were calculated, that reaching the PM_2.5 limits determined by WHO can prevent 44,617 premature deaths in Türkiye in 2018 (Pala et al., 2021). According to WHO, the annual number of deaths associated with air pollution is 7 million, and this figure is estimated to be 6.7 million according to the Global Burden of Disease 2019 (Fuller et al., 2022; Landrigan, 2017). When cause-specific rates of deaths caused by air pollution is investigated, 29% of lung cancer-related deaths, 43% of COPD-related deaths, a quarter of ischemic heart disease-related deaths, and a quarter of stroke-related deaths are found to be attributed to air pollution (WHO, 2022b). In a study where long-term exposure to PM_2.5 was evaluated with the AIRQ+ program between the years 2014 and 2019 in Iran, 15% of total COPD deaths and 17% of total lung cancer deaths were attributed to PM_2.5 (Hajizadeh et al., 2020). In studies conducted with AİRQ in different regions and with different pollutants (such as NO₂), excess deaths associated with air pollution have also been demonstrated (Al-Hemoud et al., 2021). It has been reported that in 23 countries in Europe, long-term exposure to PM_2.5 is associated with an increased lung cancer and COPD mortality rates (Goldberg, 2008). In a cohort study investigating PM_2.5 exposure in the USA for the last 20 years, positive and significant relationships were found between chronic PM_2.5 exposure and COPD and lung cancer mortality (Pun et al., 2017). In our study, while the lung cancer mortality rate attributed to PM_2.5 was around 15%, this rate was around 22% for COPD. The region with the highest mortality rate attributed to COPD is the Northeast Anatolia, whereas for lung cancer, it is Istanbul and Northeast Anatolia respectively. According to a study where long-term exposure to PM_2.5 causing premature deaths in our country in 2018 is evaluated, the region with the highest attributable mortality rate is the Aegean region (Pala et al., 2021). Since only Lung Cancer and COPD deaths were investigated in our study, there may be differences in attributable mortality rankings. Although we examined the role of outdoor air pollution in lung cancer and COPD, there are other important factors in the etiology of these two diseases, such as smoking and passive exposure (Gordon et al., 2014; Song et al., 2014).

 
5 CONCLUSIONS

To conclude, it is suggested in our study that long-term exposure to PM_2.5 may be the reason of 22% of COPD-related deaths and 15% of lung cancer-related deaths in Türkiye in the year 2019. There is no threshold limit in the legislation in our country regarding the PM_2.5 levels and national limits for PM₁₀ values are greater than WHO limits. For these reasons, the limit value for PM_2.5 should be determined, and there is PM₁₀ limit value needs to be reduced to WHO standards in our legislation. Additionally, remarkable number of air quality measurement stations do not measure PM_2.5, thus, there are requirements both in terms of the number and location of the air quality measurement stations and also in terms of increasing the variety of pollutants measured by them.

The most prominent limitation of our study is its ecological research design. Another constraint arises from the inadequate placement of air quality measurement stations within the provinces, along with the inability to measure PM_2.5 levels at certain stations. Additionally, the utilization of mortality data from TurkSTAT constitutes another limitation. The reliability of TurkSTAT's mortality data is compromised due to both delays in death data reporting and the potential underutilization of accurate diagnosis codes within the death notification system.

Turning to the study's strengths, it anticipates a connection between escalated air pollution levels and elevated mortality rates for lung cancer and COPD. Consequently, approximately one in every six lung cancer deaths and one in every five COPD deaths can be associated with exposure to outdoor air pollution.

ADDITIONAL INFORMATION AND DECLARATIONS

Competing Interests

The authors declare no competing interests.

 
Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

 
Acknowledgements

The authors would like to express sincere appreciation to Dr. Safiye Takir Stewart for their technical assistance during this research.