Relationship between the actual fine dust concentration and media exposure that influenced the changes in outdoor activity behavior in South Korea

The one reason of the decrease of walking time for adults in South Korea among various factors is the sense of fear about fine dust sparked by media reports, which has created a negative perception of fine dust. This study aimed to assess the change in concentration of fine dust, as well as individuals' walking time and health status, in South Korea, and to investigate the relationship between the media reports on fine dust. Using the national government statistics data, we analyzed the relationship between walking time, concentration of fine dust, and amount of media reports on fine dust. From 2008 to 2017, the average walking time and PM10 levels decreased from 76.17 to 49.47 min and 52 to 45 μg/m3; whereas PM10 media frequency increased from 349 to 9,234. No positive correlation existed between walking time in South Korea and exposure to fine dust. However, media reports on fine dust increased steadily from 2012 and peaked in 2015. The decrease in average walking time in South Korea was due to the negative perception created by the increase in media reports on fine dust, rather than the increase in the actual concentration of fine dust.

Interest in particulate matter (PM) among South Koreans is increasing daily. Concerned with the increase in concentration of fine dust and the resultant deterioration of the health of citizens, the Ministry of Environment of South Korea promulgated enforcement regulations "Special Act on Fine Dust Reduction and Management" in February 2019 1 . The purposes of the regulations are to reduce the emission of fine dust and the product of pollutants, manage the occurrence of such pollution to prevent the hazards associated with fine dust, preserve the atmosphere of the environment in an optimal state, and set up a comfortable living environment.
The argument has been amplified through newspapers, news, and various social media networks as a result of the 'Fine Dust Emergency Mitigation Measure' , changes in the environment, and changes in the health status of individuals. Therefore, the negative perceptions and inconveniences of the people have increased considerably 2 . The public's perception of fine dust is expressed in negative emotional terms, they are expressed together with terms with negative meaning, which are related to government activities 3 . These invisible risk issues cause citizens to have uncertainties and fears about fine dust itself, and they are as well dependent on the media for information on ways to protect themselves from these invisible risks 4 .
The National Institute of Environmental Research (NIER) of South Korea announced that fine dust occurs in boilers, automobiles, factor operation facilities, etc., and these sources account for a considerable amount of fine dust measured domestically. That is, a considerable part of fine dust generation can be attributed to domestic factors 5 . Analysis of the contributions of fine dust domestically and from foreign countries in 2018 by NIER www.nature.com/scientificreports/ National health and nutrition examination survey data. The National Health and Nutrition Examination Survey 19 is a statutory survey on the health behaviors of the public, current status of chronic diseases, and actual condition of food and nutrition based on Article 16 of the National Health Promotion Act. The data of the National Health and Nutrition Survey of South Korea was collected through the circular sample survey design of the citizens whose subjects themselves could represent South Korea. In addition, when this data is provided to researchers, there is no problem of personal information leakage because the personal information is statistically secured. In other words, there was no problem of research ethics or sampling during analysis. The National Health and Nutrition Examination Survey was conducted every 3 years from the first period (1998) to the third period (2005). Thereafter, it was reorganized as a yearly survey system and was carried out annually during the fourth period (2007)(2008)(2009)). The survey was conducted with the approval of the Research Ethics Review Committee of the Disease Control Division, and the results of the survey were published through the dissemination of press releases, statistical publications, and publication of the original data until December of the next year.
We analyzed the data from 2008-2017. The variables analyzed for the general characteristics were sex, age, house-hold income, education level, occupation group, and subjective health status. To assess health status, data on systolic blood pressure, diastolic blood pressure, body mass index, fasting blood sugar, Hemoglobin A1c (HbA1c), total cholesterol, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol were analyzed. The dependent variables were walking level and duration (in minutes). The average walking duration was measured for South Korea and the metropolitan city, Seoul (Fig. 2).
Environmental statistics yearbook data. We used data from the Environmental Statistics Yearbook 20 , which included measurements of air quality and PM 10 in South Korea. This data control is the based cities code merge the PM 10 data in Korea National Health and Nutrition Examination Survey Data cities code. Therefore, average PM 10 levels in a decade was calculated for the whole nation. The variables used were PM 10 for the whole nation's average and PM 10 and PM 2.5 for the metropolitan city, Seoul's average.

Ministry of statistics Korea city and province basic statistics data. Data from the Ministry of
Korea City & Province Basic Statistics were used 21 . The data included the number of parks and sports sites. This variable was used to assess the relationship between the city environment and walking time.
Ministry of statistics social survey data. We used data from the Ministry of Statistics Social Survey 22 to assess safety consciousness and policy making and utilization of basic data for people. The data used included the awareness of social safety and fear of walking at night. The survey is conducted biennially, and the years included for this study were 2008, 2010, 2012, 2014, and 2016. Social safety was summarized using good safety line and bad safety line. The awareness of good social safety was indicated by 'very safe' and 'often safe' , whereas the awareness of bad social safety was indicated by 'often not safe' and 'very not safe' .
Press foundation-news big data and analysis system: the big kinds-mass media exposure data. We used Press Foundation is open provide social mass media exposure data in news big data & analysis system: The Big Kinds 23 . We searched for information on PM 10 mass media exposure using these keywords: 'find dust' , 'PM 10 ' , or 'Particulate Matter 10' , These keywords exposure to the South Korea. It's exposure frequency through press company.

Statistical analysis.
We used the open source statistical software R version 3.6.0 for all statistical analyses.
Descriptive frequencies were used to analyze general characteristics; descriptive statistics to analyze PM 10

Results
General characteristics. We were subjects total 20,605 persons in National Health and Nutrition Exami-  Trends for awareness of social safety and Afraid for night walk in South Korea. The awareness of social safety was described as either good safety line or bad safety line. Awareness of good social safety line increased whereas that of bad social safety line repeatedly decreased and increased. Trends on fear of walking at night did not change (Fig. 6).     (Table 3).
Trends for health examination in South Korea. Health Examination variables were systolic blood pressure, diastolic blood pressure, body mass index, fasting blood sugar, HbA1c, triglycerides, total cholesterol,        (Table 5).

Discussion
This research was based on the fact that South Korea has a conducive physical environment (number of park, number of sport site, decreased PM 10 ) and a friendly social environment (increased awareness of good social safety, increased budget of health, increased budget of land and area development) for walking. However, in the last decade, the national average time for walking has decreased. From ' Fig. 3' , one would observe that the walking time (minutes) has decreased, whereas the PM 10 mass media exposure frequency increased. At the same time, the health status of residents of South Korea have deteriorated according to health examination data, and this has been reasoned to be as a result of the reduction in walking behaviors. The beneficial effects of walking on health include the reduction in systolic blood pressure, diastolic blood pressure, triglycerides, total cholesterol, fasting blood sugar, and HbA1c [24][25][26][27][28][29][30][31] . Therefore, we presumed that the reduction in walking behaviors among residents of South Korea is as a result of the fear of increased mass exposure to air pollutants, such as PM 10 , which they

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Year mean (SD) Year mean (SD)  www.nature.com/scientificreports/ think may expose them to some forms of danger. But this really factors the decreased PM10 decennary. And South Korea's Average year PM 10 was not danger and many improve the air quality than past 10 years, for the do not walking and do not health benefits. South Korea governments fighting making policy and finance the budget for improve air quality and good for healthy environment & good for social safety environment. This really problem is the press companies over exposure of the mass media output results that it. Examples reference of negative health affect mass media exposure, television and magazine were Internalization of the thin beauty ideal, social comparison, and activation of the thinness schema are clearly among the processes which mediate the effects of the media on body dissatisfaction, weight concerns and disordered eating behaviors32. Mass media was not every day positive affect. This influence of particulate matter risk perception in the public is reflected to various type of risk related environmental, social and economics [33][34][35][36] . You et al. 34 said that the large amount of media reports on uncertain basis of the particulate matter frame affects the physical activity of the public. In others studies 37,38 said that the public is perceived and more reacts about the risk of particulate matter due to increase of media coverage and warning message. According to data from the Korean National Health and Nutrition Examination survey 19 , the average walking time of people aged above 19 years is decreasing year by year. The reasons for this are the lack of absolute walking time due to long working hours 39 , lack of ecological 40 and suitable urban environment-facility 41 , the amount of health-related budget input for walking in the city or bicycles 42 , and awareness of city safety for living 43 . Furthermore, Various studies have reported that economic crisis affects health related behavior [44][45][46] . Studies that examined changes in health behaviors of Icelandic people due to the economic crisis indicated that the economic crisis is responsible for the reduction of health-compromising behavior and health-promoting behavior 44 , another study in Spain said that it caused health-related behavior changes due to economic-financial crisis 45 . On the other hand, as a result of analyzing changes in the health-related behavior of Greeks due to the financial crisis, physical activity increased during the first economic crisis in 2006 and the second economic crisis in 2011 46 . In the case of Korea, the crisis triggered in the US financial market in 2008 spread to the world, and the economic crisis began and continued in Korea. As a result, the psychological burden of the people was increased, consumer life was greatly reduced, and activities in all fields were stagnant 47,48 . In response to this economic crisis, the public focused on job search and alternative economic activities, showing a decrease in physical activity such as walking 47 . These suggest that the problem is not only a factor of the individual but also a factor of the various ecological backgrounds that can affect the walking time 49,50 . In our study, walking time decreased in spite of the increase in ecological urban sites and the positive awareness of unban safety (Table 3). If this is the case, then the cause of the decrease in walking time is likely a factor of the change in the individual perception level. Therefore, the change in perception was attributed to an increase in awareness of the crisis due to increased media reports related to fine dust in this study. A study by Kim et al. 51 conducted a frame analysis and a source analysis of a fine dust reporter to examine the risk perception of fine dust. During the frame analysis, it was found that the amount of articles reported on an uncertain basis was quite large, and the most frequently used experts as sources of information. In addition, Kim et al. 52 said that communication and media studies have a profound effect on the people living in modern times, and that a large amount of articles reported as an uncertain basis during the analysis of the fine dust frame affects people's physical activities. Also, people are increasingly aware of the dangers of particulate matter due to increased media coverage and warning messages 37,38 .
PM risk perception is not only a real risk to health, but also a complex phenomenon affecting changes in public opinion and policy 53 . For example, Outdoor activity such as walking are limited by the level of particulate matter 54 . The limitation of these outdoor activity brings about the increase in economic burden due to the use of defensive products, such as mask or air filters, and the increase of alternative service to replace the traditional outdoor activity, expansion of indoor activity, such as yoga and weight training 55,56 . In addition, South Korea is a country with very well-developed Internet and Social networking service and particulate matter risk perception is formed depending on the frequency of media reports regardless of the actual frequency of occurrence and the risk of harm to health 57 . In a summary, South Korea's particulate matter-related policies should take into account not only economic development but also social point of view 58 .
These type of media report which address above, for example, "The inflow of fine dust from China increased up to 86%" 59 as a foreign factor, gave the people a sense of 'fine dust = China' . However, this was only the result of the analysis of a certain period of China's influence. In fact, the concentration of fine dust in most areas of China has decreased, but the uncertainty of the increase in fine dust concentration due to the relocation of a specific industrial complex in China has increased the public's fear about fine dust 59 . Even if it is not solely the risk of fine dust created by media coverage, the media's influence on perception of risk factors related fine dust cannot be ignored 60 . Previous reports 15 indicated that the concentration of fine dust in Korea has been on a declining trend since 2007, but only slightly increased in 2013. In Kim's study 15 , as reported in our research, the news of fine dust-related media rapidly increased from the year 2013, and the perceived risk that did not actually exist tends to be misconstrued as a risk issue due to the explosive increase in media coverage. In addition, despite the fact that these studies are media reports related to fine dusts, there has been an increase in the number of reports for the purpose of promoting and selling specific products. The problem with these reports is that they can provide distorted information to achieve commercial purposes rather than present solutions to effectively address such risk situations as fine dust.
Fine dust is very small in size and enters the body through the breath of man, accumulates, and causes various health problems 61 . Many studies have reported that exposure to micro dust promotes mortality-related illnesses, such as changes in blood pressure, respiratory diseases, cardiovascular diseases, and stroke [62][63][64] . Other studies have reported that, as well as health problems causing damage to the industry, such as primary industries, transport, and manufacturing 65 . Due to these negative effects, the public interest and concern about fine dust increases with the passage of time. To do this, accurate research and policy should be established so that the public can understand and judge correctly, without explaining the causes of the risk factors, not only in the media but www.nature.com/scientificreports/ also in government and academia. Min 66 proposed the countermeasures of each institution for effective resolution of fine dust. First, the government should establish a solution through an integrated approach involving ministries. Second, the communication between the ministries and the public should be more open than the existing methods and it is necessary to improve the current administrative procedures and customs which may be obstacles to the identification of risk factors. Kim et al. 57 said that in South Korea, where the Internet and social networking service is very well-developed, the public perception is formed almost by the frequency of media reports regardless of the actual concentration and frequency of particulate matter and its harmful effects on health. In addition, some studies 67,68 show that the public overexposed to fragmented media reporting environmental stress factors such as particulate matter 69 negatively aware of risk related health by emphasizing the role of communication for the public. Third, it is suggested that academia should have a consciousness to solve the problem of air quality pollution, and should be able to converge various opinions based on an open research climate. Finally, the media should be able to fulfill the positive role of the media through fair reporting, devoid of the indulgence of irritating themes, and to be able to wait for "the right time" of academics and government. The government's interpretation and reflection of the policy should not lose the sense of the cold report 66 .
The limitations of our study are as follows. First, we did not control for bias from variables that could influence the correlation between micro dust media footprints and walking time reduction. The data were analyzed by two approaches, which were gradually based on the information provided by public authorities to determine their relevance; it seems a missed approach and the nature of the difficulty of interesting items of secondary materials. In addition, the reliability and validity of the analysis depends on the ability of the researcher to select the necessary information in the secondary data 70 . Seconds, we could not determine the actual effects of decreased walking time on human health and health effects in detail. This is also as a result of the limitation from the use of secondary data, which seems to be a missing item of interest. Despite these limitations, our study utilized a variety of secondary materials from credible public institutions that had conducted possible large-scale investigations, which were not limited to simple health data, weather, media reports, the government budget, but included combined and the bias was reduced.

conclusion
This research question was whether the decreasing walking time of the Korean people was really related to the increase in the concentration of fine dust. It was found that various variable affect the walking time of the Korean people rather than the concentration of fine dust actually increasing. Especially, the number of media related to fine dust affected the walking time of Korean people rather than the actual concentration of fine dust. We conclude that the increase in indiscriminate media reports without identifying various internal and external factors of risk factors, such as explosive increase in fine dust concentration, could be the cause. In addition, by analyzing various variables, such as the number of health behavior practice sites (number of parks, number of sport sites), awareness of social safety, and afraid of night activities, related to changes in walking time and health status during this period, it was concluded that a decrease in physical activity could have a negative impact on health status. Therfore, these phenomena are not not temporary or rapid, as our results. So, this study hope to call attention of all walks of life for the citizens of the Republic of Korea to change health-related behaviors.