Costs of environmental tobacco smoke in Korea

Trends in tobacco smoking

The survey asks about current smoking status and the age at which respondents first started smoking, but not whether respondents are ex-smokers. It also asks how many cigarettes current smokers smoke in a day, which averages about 12-19 cigarettes per day depending on age and sex, but we use only the yes-no response for current smoking status to analyze the risk of using tobacco and effectively assume that the risk of using tobacco corresponds to smoking an average amount of cigarettes.

Active smokers were defined as people who had smoked at least 100 cigarettes previously in their lifetimes and continue to smoke on a daily basis at the time of the survey. People other than active smokers were defined as non-smokers, which included occasional or part-time smokers, ex-smokers and never smokers. Because active smokers are defined as daily smokers, the numbers of active smokers under-estimates the number of people who have smoked tobacco and can be expected to have health effects from occasional or past smoking.

According to the survey, tobacco smoking rates on average and for men have declined somewhat since 2005, although they remain significantly higher than women’s smoking rates. Figure 1 and Table 1 show that tobacco smoking rates on average declined from 28.8% in 2005 to 23.2% in 2013, although the decline was not monotonic. Smoking rates for men declined from 52.3% in 2005 to 41.4% in 2013, although the decline was not monotonic.

Table 1.

Percent of smokers for men and women and on average in Korea, 2005-2013

Women’s tobacco smoking rates have risen at times since 2005, although they remain significantly lower than men’s tobacco smoking rates. Figure 1 and Table 1 show that tobacco smoking rates for women were 5.7% in 2005 and in 2013, and in the intervening years the rates fell and rose slightly.

Table 1 shows standard errors below the responses in parentheses. Figure 1 represents the standard errors by creating band in lighter colors around the value of the (estimated) response, equal to equal to 2 times the magnitude of the standard deviation, labeled with a “+” and a “–”.

Trends in environmental tobacco smoke exposure

According to the survey, those exposed to ETS are not active smokers—that is, they are classified as non-smokers—even though active smokers can also be exposed to ETS in addition to their own smoke. Active smoking is assumed to be a more important causative factor for disease than passive or environmental tobacco smoke.

The questions about ETS exposure were self-assessed, as were the questions about active smoking. Participants were asked about ETS exposure at home and at work separately. If participants said that any household member smoked at home (in the house), they were reported as being exposed to ETS at home. If participants said that they could smell tobacco smoke at work, they were reported as being exposed to ETS at work. The survey does not have a single question about exposure both at home and at work together, but we later try to analyze the effect of combined exposed at home and at work.

Except for the fact that there are separate questions about ETS exposure at work or at home, there is also no question about the degree or the frequency, duration or severity of exposure. The survey does not ask about exposure to ETS outside of the home or workplace, such as at restaurants and bars, nor does the survey ask about past exposure to ETS. But because the survey is an annual survey, we assume that exposure to ETS means generally or occasionally during the last year, according to the assessment of the participants.

Figure 2 and Table 2 show exposure to environmental tobacco smoke (ETS) at home. Females have more ETS exposure than males because men—husbands, fathers, uncles, brothers, grandfathers, et cetera—typically smoke more frequently at home, thereby exposing female family members. In a household with multiple adult members, men with higher smoking rates would tend to expose non-smoking women more frequently to ETS. Women have such low smoking rates that they should only infrequently expose non-smoking males to ETS within a household. A male smoker could expose other males in the household who are non-smokers to ETS, but apparently this is not common.

Figure 2.

Percent of smokers for men and women and on average in Korea, 2005-2013

Table 2.

Percent of non-smokers exposed to ETS at work or at home in Korea, 2005-2013

Like tobacco smoking rates for men, rates of exposure to ETS at home have fallen since 2005—for men, for women and on average. The ETS exposure rate at home for women was 23.9% in 2005, but only 13.7% in 2013. The ETS exposure rate at home for men was 7.1% in 2005 and 5.4% in 2013. On average, the ETS exposure at home has fallen from 18.3% in 2005 to 10.6% in 2013.

As for ETS exposure at work, we see different levels and trends. Table 2 and Figure 3 show that ETS exposure for men at work is higher than it is for women at work. This would occur when more men work than women (and therefore men have a larger potential for exposure at a workplace with tobacco smoke) and more non-smoking men associate or work with male colleagues who smoke at the workplace relative to non-smoking women.

Figure 3.

ETS exposure at home men and women and on average in Korea, 2005-2013

In addition, we do not see a downward trend in ETS exposure at work like we saw for ETS exposure at home. For men in the workplace, ETS exposure has risen from 45.3% in 2005 to 58.5% in 2013, although the rise has not been monotonic. For women in the workplace, ETS exposure has risen from 34.0% in 2005 to 39.6% in 2013, although the rise has not been monotonic. On average, ETS exposure in the workplace has risen from 38.6% in 2005 to 48.3% in 2013.

We can not explain these upward trends given the restrictions on workplace and public smoking that have been put in place since 2005 and given the decreasing number of men who smoke since 2005. Perhaps due to the restrictions on workplace and public smoking, survey respondents have become more aware of ETS and therefore have become more likely to report it.

The percent of non-smokers who are not exposed to ETS at home has increased for both men and women, as shown in Figure 4 and Table 3. We calculate this percent as a residual, equal to 100% minus the percent of smokers (by sex) minus the percent of those exposed to ETS at home (by sex). This residual has increased for men from 40.6% in 2005 to 53.2% in 2013 because both the percent of male smokers and the percent of male household members exposed to ETS have decreased. This residual has also increased for women from 70.4% in 2005 to 80.6% in 2013 because the percent of female household members exposed to ETS has decreased, while the percent of female smokers has been roughly stable. On average, this residual has also increased from 52.9% in 2005 to 66.2% in 2013, although the trend has not been monotonic.

Figure 4.

ETS exposure at work for men and women and on average in Korea, 2005-2013

Table 3.

Percent of non-smokers who are not exposed to ETS, 2005-2013

In general, Figure 4 and Table 3 show that the percent of male non-smokers not exposed to ETS at home is higher than it is for females, apparently because male non-smokers more frequently have female spouses at home who are also non-smokers. On the other hand, female non-smokers should more frequently have male spouses at home who are smokers because men smoke at much higher rates.

Figure 5 and Table 3 show the percent of male and female non-smokers not exposed to ETS at work. In contrast to the results that we see for ETS exposure at home, the percent of male non-smokers not exposed to ETS at work is lower than it is for females, because males are less frequently non-smokers and likely because non-smoking men more frequently have (male) colleagues at work who create ETS.

Figure 5.

Percent of non-smokers who are not exposed to ETS at home, 2005-2013

For females, this residual is large but has decreased from 60.3% in 2005 to 54.7% in 2013, because the percent of female workers exposed to ETS has reportedly increased. Recall that less than 10% of women report themselves as active smokers.

For males, the percent of non-smokers not exposed to ETS at work is close to zero and sometimes negative, especially in 2010 when the standard error for men exposed to ETS in the workplace was particularly high. Essentially, all males report themselves as either smokers or exposed to ETS at work, and some years the residual value of non-smoking males not exposed to ETS even becomes negative because of the (standard) errors involved in surveys.

To avoid the impossibility of having a negative percent of non-smoking males not exposed to ETS in the workplace, we subtract the value of the standard error from the reported percent of ETS exposure and the value of the standard error from the reported percent of smoking. This reduces the reported values and therefore increases the residual values in all cases to at least 0%. We use the residual values to calculate the risks of contracting 5 diseases from smoking and ETS exposure, as well as the background or baseline risk that exists without smoking and ETS exposure.

Relative risks from ETS and smoking tobacco

Behan, Eriksen and Lin (2005) calculated the risks of contracting five diseases from ETS exposure by summarizing the results of hundreds of published studies involving tens of thousands of cases for men, women or both sexes. These diseases are lung cancer, cervical cancer, coronary heart disease, COPD and asthma. Except for cervical cancer, the authors found no significant difference between cases involving men and women, across the studies. Table 4 shows average risk of contracting each disease from ETS that the authors found relative to the background or baseline risk (which is normalized to 1.00). For example, the relative risk for lung cancer is 1.22, indicating that the risk of contracting lung cancer is 22% higher when non-smokers are exposed to ETS than when they are not exposed to ETS.

Table 4.

Risks from smoking tobacco and from ETS exposure for various diseases, relative to the baseline risk

The table also shows the risk of contracting each disease from smoking tobacco relative to the baseline risk as estimated by Kang, et alia, (2003); Jones, et alia, (1990); Lederle, et alia, (2003); and Barclay (2008). These numbers range from 7.2 for chronic obstructive pulmonary disease (COPD) to 1.7 for cervical cancer, indicating that smokers are 620% more likely to contract COPD and 70% more likely to contract cervical cancer compared to non-smokers not exposed to ETS, who face a background or baseline risk nonetheless.

Number of cases of five tobacco-related diseases

Table 5 shows the number of cases of the five diseases for the most recent year for which we have data, as well as the cases per 100,000 people in the targeted population. Chronic obstructive pulmonary disease (COPD) was the most common disease in Korea, with about 2.4 million cases in 2012, with men being afflicted more than three times as much as women. There were also about 53,100 total cases of lung cancer in 2012, with about 2/3 of these cases afflicting men. There were about 959,000 cases of heart disease in 2005, the most recent year for which we have data. From 2007-2012, we have data for acute myocardial infarction, a kind of coronary heart disease in which the heart tissue dies due to a lack of blood supply. (Other kinds of coronary heart disease include ventricular fibrillation and congestive heart failure.) In 2012, there were about 236,000 cases of acute myocardial infarction. Coronary heart disease in general afflicts males and females about equally, while acute myocardial infarction in particular afflicts males almost twice as much as females. There were about 914,000 cases of asthma in 2012, which afflicted men and women about equally. In 2012, there were more than 43,000 cases of cervical cancer.

Table 5.

Number of cases and estimated risk for 5 diseases affected by smoking and ETS

Table 6, Figure 6 and Figure 7 show the trends in the rates of these diseases during the past several years. Lung cancer and cervical cancer exhibited a large increase a few years ago, although changes in reporting and diagnosis could be the reason for these changes. Figure 6 shows that the risks for lung cancer and cervical cancer have risen during 2007-2012, and that men’s rates of lung cancer are about 2 times as high as women’s rates for lung cancer.

Table 6.

Number of cases for 5 diseases affected by smoking and ETS, 2005, 2007-2012

Figure 6.

Percent of non-smokers who are not exposed to ETS at work, 2005-2013

Figure 7.

Average risk (rates) of lung and cervical cancer in Korea, 2007-2012

Cases of COPD and asthma have not significantly increased in the past few years, and have sometimes decreased. Figure 7 shows that the rates of COPD remain significantly higher than for men than for women, but the rates of asthma for both sexes are roughly comparable. Acute myocardial infarction has increased during the past several years for both males and females, although the magnitude of the increase is small relative to the magnitude of cases of COPD and asthma.

The onset of asthma can happen quickly, whereas the onset of COPD and cancer takes years or even decades. So if smoking rates and ETS exposure have fallen, reported asthma cases can quickly fall too, but the trends for COPD and cancer depend on smoking behavior and ETS exposure years prior.

Notice also that risk of COPD and asthma are about 10-100 times larger than the risk of cancer. The risk of coronary heart disease is comparable to the risk of asthma for both sexes, at about 4880-5007 cases per 100,000 people, but we have data only for 2005. The risk of acute myocardial infarction is somewhat smaller than the risk of asthma for both sexes.

Given the total number of cases and the risks of contracting the diseases in a given year, we next estimate the number of cases suffered by smokers, non-smokers who are exposed to ETS and non-smokers who are not exposed to ETS.

Figure 8.

Average risk (rates) of COPD, asthma and acute myocardial infarction in Korea, 2007-2012

Estimation of baseline cases

We start first with estimating the number of cases suffered by non-smokers who are not exposed to ETS. These cases are called baseline cases, and they are supposed to come from a baseline or background risk absent of smoking tobacco and ETS exposure.

We estimate the baseline risk with a function of the average risk of contracting the disease, as well as functions of the percentages of and risks for smokers and of non-smokers exposed to ETS. For example, suppose that the actual number of cases of chronic obstructive pulmonary disease (COPD) is 2,398,449. These people would be active smokers, ex-smokers, non-smokers currently exposed to ETS, non-smokers currently not exposed to ETS and non-smokers never exposed to ETS. For a population of 23,562,416 for both sexes in 2012 who were 40 years or older, 11,174,562 for males in 2012 who are 40 years or older and 12,387,853 for females in 2012 who are 40 years or older; the cases per 100,000 people in the relevant population would be 10179 (or about 10.2%) on average, 16322 (or about 16.3%) for males and 4600 (or about 4.6%) for females.

But these calculations represent the average risk to smokers, non-smokers exposed to ETS and non-smokers not exposed to ETS who are exposed to the baseline risk. The relative risk of COPD for active smokers is estimated to be 7.2 times the baseline risk for non-smokers not currently exposed to ETS; the relative risk of COPD for those currently exposed to ETS is estimated to be 1.83 times the baseline risk, as shown in Table 4. So the baseline risk should be smaller than the average risk, while the risk to smokers should be larger than the average risk.

We estimate baseline risk from the average risk in the following way. Let the proportion of smokers be ps, the proportion of non-smokers currently exposed to ETS be pets and the proportion of non-smokers currently not exposed to ETS be p_{ns_nets}. And let the risk for smokers be rs, for those currently exposed to ETS be rets, and for non-smokers currently not exposed to ETS be r_{ns_nets}. r_{ns_nets} is also called the baseline risk. If we assume that these 3 groups are mutually exclusive and collectively exhaustive (ignoring ex-smokers and non-smokers previously exposed to ETS), then the (weighted) average risk that is observed by looking at the number of cases and people’s tobacco smoke exposure equals

We next use risks relative to the baseline risk:

where rr_s is the risk of contracting a disease for smokers relative to the baseline risk, rr_ets is the risk of contracting a disease for non-smokers currently exposed to ETS relative to the baseline risk and 1.00 represents relative risk for non-smokers not currently exposed to ETS.

Therefore, the baseline risk, r_{ns_nets}, equals

For example, when the average risk equals 0.16322 or 16322 cases per 100,000; the relative risk for smokers equals 7.2, the relative risk for non-smokers exposed to ETS equals 1.83, the proportion of male smokers equals 43.3%, the proportion of male non-smokers currently exposed to ETS equals 52.9% and the proportion of male non-smokers not currently exposed to ETS equals 7.0%; then the baseline risk for male non-smokers not currently exposed to ETS equals

or 4.047%. Estimated cases of COPD not linked to active smoking or ETS (“baseline cases”) equal this baseline risk times the percent of the male population who neither currently smokes (nor previously smoked) nor are (nor have been) exposed to ETS = 4.047% × 7.0% = 0.002833 = 283.3 cases per 100,000. 283.3 cases per 100,000 represents 1.7% of the total 16322 observed cases for men.

The estimated risk of COPD from ETS equals 1.83 times the baseline risk or 7.41%. Estimated cases from ETS equals this risk times the percent of the male population who is currently exposed to ETS, or 7.41% × 50.9% = 0.03770 = 3770 cases per 100,000. 3770 cases per 100,000 represent about 23.1% of the total 16322 observed cases for men.

The estimated risk of COPD from smoking equals 7.2 times the baseline risk or 29.14%. Estimated cases from smoking equals this risk times the percent of the male population who smoke tobacco, or 29.14% × 42.1% = 0.12382 = 12382 cases per 100,000. 12382 cases represents about 75.9% of the total 16322 observed cases for men.

For females, we estimate baseline cases as

or 2.673%. Estimated baseline cases of COPD equal this baseline risk times the percent of the female population who neither currently smokes (nor previously smoked) nor are (nor have been) exposed to ETS = 2.723% × 56.5% at most = 0.01510 at most = 1510 cases per 100,000 at most. 1510 cases per 100,000 represents 32.8% of the total 4600 observed cases. I write “at most” because the calculation does not consider women exposed to ETS at home, so it neglects some of the cases that were caused by ETS exposure, thereby inflating the number of cases attributable to baseline risk. But in a later calculation we consider ETS exposure at home in addition ETS exposure at work.

Table 7 shows that for both sexes and for all diseases the estimated baseline risk (per year) ranges from about 4.0% (for COPD) to about 0.1% (for cancers). This risk is similar between sexes for lung cancer, coronary heart disease and acute myocardial infarction, but about 2 times higher for women for asthma, and about 1.5 times lower for women for COPD. Differences between sexes can arise due to reporting errors or due to the fact that the calculation does not account for ex-smokers, who should have a higher risk for diseases than the baseline risk. The population of ex-smokers is likely to be different across sexes, since it is likely that men and women to not quit tobacco at the same rate. The calculation also does not account for the intensity or duration of smoking or exposure to ETS, which is also likely to differ across sexes.

Table 7.

Baseline risk and estimated cases from baseline risk per 100,000 people, 2012

Table 7 also shows the estimated cases per 100,000 people (in the age-appropriate population) who are predicted to contract a disease from baseline risk and the percent of total cases that are contracted from baseline risk. Even though the baseline risks are roughly similar between sexes, because so few men are non-smokers who are not exposed to ETS, only about 2%-5% of the total number of cases for each disease for men are predicted to be caused by baseline or background risk. Baseline or background risk is predicted to cause a larger percent of cases for women, on the order of about 28%-57%, because a larger fraction of women are non-smokers who are not exposed to ETS. For example, about half of the cases of coronary heart disease and acute myocardial infarction for women are predicted to be caused by baseline risk, whereas only about 5% of cases for men are predicted to be caused by baseline risk. Note that women have only about 60% as many cases of acute myocardial infarction as men, probably because women smoke less, as shown in Table 5 and Table 6. However, women have about the same number of cases of coronary heart disease in general as men, which has many causal or contributing factors such as diet and a sedentary lifestyle.

Estimated cases from ETS

Using the formula above, we estimate the number of cases from ETS exposure at work for males and females for the 5 diseases. In addition, we consider ETS exposure at home, at least for females.

The survey does not ask about the frequency, duration or severity of ETS exposure. It does not distinguish among people exposed to ETS at home only, people exposed to ETS at work only and people exposed to ETS both at home and at work. In general, ETS exposure at work and/or at home would likely cause more cases of disease than ETS exposure only at work or only at home, because the frequency, duration or severity of exposure would be greater. Depending on the year, the survey results tell us that approximately 34%-42% of women are exposed to ETS at work and approximately 15%-24% of women are exposed to ETS at home according to the response to a separate question. We first consider ETS exposure at work according to a single survey response, and then estimate ETS exposure at work and ETS exposure at home together in the following way.

Because about 50% of adult women are in the labor force, we estimate that the number of women exposed to ETS at work or at home during the same period as 34%-42% + 0.5×(14%-24%). This calculation assumes that 50% of women who answer the survey do not participate in the labor force and face the same ETS exposure rates at home as women in general. But in reality, those who do not participate in the labor force might face ETS exposure rates lower or higher than the reported 14%-24%. Also, some women might be exposed to ETS at work and at home, increasing the frequency, duration and severity of exposure relative to being exposed to ETS at work or at home.

But because nearly all men are either exposed to ETS at work or are smokers themselves and because so few men are exposed to ETS at home, we do not estimate this case for men. Given the already high percent of male smokers and males exposed to ETS at work, adding to the percent of men exposed to ETS at home would often make the estimation of baseline cases untenable because the percent of non-smoking men not exposed to ETS would be estimated at less than 0%.

Table 8 shows that the estimated number of cases from ETS exposure at work for men and women and at work or at home for women. Recall that men generally have higher ETS exposure at work, but women generally have higher ETS exposure at home. Notice also that the estimated number of cases for ETS exposure at work or at home together for women are higher than the number of estimated cases for ETS exposure at work only.

Table 8.

Estimated cases per 100,000 people from ETS exposure, 2005

The estimated number of cases from ETS exposure is higher for women than for men for coronary heart disease (CHD) in 2005 because men are more frequently smokers than women so more of the causation of CHD for men is attributed to active smoking. (See Table 9.) When we consider ETS exposure at work or at home for women, the estimated number of cases from ETS exposure is even higher. There were 1543 estimated cases of CHD per 100,000 men in 2005 due to ETS exposure and 1614-2157 estimated cases of CHD per 100,000 women in 2005 due to ETS exposure.

Table 9.

Estimated cases from smoking per 100,000 people, 2005-2012

However, for acute myocardial infarction (2007-2012) specifically, the estimated number of cases from ETS exposure is higher for men than for women, although the estimated number of cases of acute myocardial infarction for women rises by about 20%-25% when we consider ETS exposure at work or at home, similar to the 33% increase in the estimated number of cases for CHD. There were 427-509 estimated cases of acute myocardial infarction per 100,000 men and 249-363 estimated cases of acute myocardial infarction per 100,000 women from 2007-2012 due to ETS exposure.

For asthma, the estimated number of cases is higher for women than for men. Again, because men are more commonly smoke than women, more of the causation of asthma is attributed to active smoking for men than to ETS. There were 546-814 estimated cases of asthma per 100,000 men and 980-1634 estimated cases of asthma per 100,000 women from 2007-2012 due to ETS exposure. The estimated number of cases first rose and then fell for both men and women, as the total number of cases rose and fell, as smoking rates for men and ETS exposure at home for women fell and as ETS exposure at work for both sexes generally rose.

For COPD, the estimated number of cases from ETS exposure at work is higher for men, at 3204-4808 cases per 100,000 men, than for women, at 1800-4778 cases per 100,000 women from 2007-2012. For men, the estimated number of COPD cases from ETS exposure has fallen then risen, while the estimated number of cases for women has fallen, even though ETS exposure rates at work for both sexes have generally risen. However, because COPD can take years for onset, we should focus on average levels over the entire survey instead of annual changes.

For lung cancer, the estimated number of cases from ETS exposure at work is also higher for men, at 44.8-78.0 cases per 100,000 men, than for women, at 26.6-63.6 cases per 100,000 women.

For cervical cancer, the estimated number of cases has risen during 2007-2012, from 29.1 cases per 100,000 women to 67.7 cases per 100,000 women for those exposed to ETS at work. For women exposed to ETS at work or at home, the estimated number of cases has risen from 35.7 cases per 100,000 women to 79.0 cases per 100,000 women. The estimated number of cases for ETS exposure at work or at home are about 20% higher than the estimated number of cases for ETS exposure at work only. There was a sharp increase in the estimated number of cases in 2010 for those exposed to ETS as the number of reported cases increased significantly.

Estimated cases from smoking

Table 9 shows that the estimated number of cases from smoking is much greater for men than for women, with the exception of cervical cancer. Recall that men generally have higher smoking rates that are almost 10 times as high as those for women.

COPD is the most common disease for male and female smokers, and active smoking is predicted to cause about 75% of the 14,000-20,000 cases per 100,000 men from 2007-2012. The estimated number of cases of COPD from smoking was 11175-15305 per 100,000 men and 1160-1978 per 100,000 women. Because women smoke much less, the estimated number of cases of COPD for female smokers is much smaller than for male smokers, although these cases are still large compared to cases of other diseases for women. For men and women, the estimated number of COPD cases has fallen then risen from 2007-2012, following the trend in the total reported cases per 100,000 people shown in Figure 7.

There were 3300 estimated cases of coronary heart disease per 100,000 men in 2005 due to smoking and 463-468 estimated cases of coronary heart disease per 100,000 women in 2005 due to smoking. For acute myocardial infarction, male smokers were predicted to suffer from 665-793 cases from 2007-2012, and female smokers were predicted to suffer from 59-85 cases from 2007-2012.

For asthma, there were 1195-1955 estimated cases of asthma per 100,000 men due to smoking and 362-652 estimated cases of asthma per 100,000 women due to smoking from 2007-2012. The estimated number of cases first rose and then fell for men, and for women there was no discernible trend.

For lung cancer, the estimated number of cases from smoking is higher for men, at 129.6-230.9 cases per 100,000 men, than for women, at 11.4-33.7 cases per 100,000 women. For women, the estimated number of lung cancer cases has steadily risen from 2007-2012, and for men there was a significant increase in 2010, following the trend in the total number of cases.

For cervical cancer, the estimated number of cases for female smokers has risen during 2007-2012, from 4.5 cases per 100,000 women to 14.5-14.9 cases per 100,000 women, depending on whether we consider ETS exposure for others at work or at home, or at work only. When we consider women exposed to ETS at work or at home, the estimated number of cases is not much different. Notice that the estimated number of cases of cervical cancer attributable to smoking are about 5-8 times smaller than the estimated number of cases of cervical cancer attributable to ETS exposure, even those the risk of contracting the disease is higher for smokers. Because the number of female smokers is reported to be so small, the number of cases attributable to smoking is likewise small.

Direct medical costs from ETS

Given the estimated number of “excess” cases from ETS and active smoking relative to the baseline number of cases, we next estimate the cost of treating them, given the average cost of medical treatment. We conjecture that because ETS exposure and smoking cause more cases of disease than would occur otherwise, the cost of treating these diseases increases for each additional case at the average rate, although in reality the cost of treatment may increase at an increasing rate as resources become more scarce or may increase at a decreasing rate as economies of scale take effect.

We find that even though cancer is a relatively rare disease, the cost of treatment is relatively expensive. Lung cancer costs about 14 million won to treat for an average case, approximately equal to US$14,000. Because the number of cancer cases has risen in the past 5 years, the total cost of treating cancer has risen. The total cost of treating men has risen from 652 million won in 2007 to 1093 million won in 2012. For women, the cost has risen from 464 million won in 2007 to 891 million won in 2012 when we estimate the number of cases from ETS exposure at work or at home.

Cervical cancer costs about 4 million won to treat an average case. The estimated cost of treating women exposed to ETS at work or at home has risen from 147 million won to 325 million won. Because the estimated number of cases from ETS exposure only at work and ETS exposure at work or at home were nearly the same in each year, the estimated total cost of treating cervical cancer was nearly the same whether we considered ETS exposure at home or not.

However, because the onset of lung cancer and cervical cancer can take decades, the estimated total medical costs presented in Table 10 (and Table 11) might be better interpreted as the estimated future total medical costs for those currently exposed to ETS (and those currently smoking) if current trends continue indefinitely.

Table 10.

Total direct cost due to cases attributable to ETS, 2005-2012

Table 11.

Total direct cost due to cases attributable to smoking, 2005-2012

The costs of treating coronary heart disease, acute myocardial infarction, COPD and asthma are inexpensive relative to the costs of treating cancers, at about 1.3 million-3.3 million won for an average case. But because there are large amounts of cases, the estimated total costs of treating these diseases are larger than for treating cancers.

However, because the number of reported cases of COPD for women and men has generally fallen or remained stable, the cost of treating cases attributable to ETS exposure has fallen or remained stable as well, even though the percent of the population exposed to ETS at work has risen slightly. For men exposed to ETS at work, the estimated total cost of treating COPD has fallen from about 11.9 billion won to about 9.3 billion won during 2007-2012. For women exposed to ETS at work or at home, the estimated total cost of treating COPD has fallen from about 10.8 billion won to about 4.7 billion won.

As for asthma, costs have risen or fallen as the number of estimated cases from ETS exposure have risen or fallen. For men exposed to ETS at work, the estimated total cost of treating asthma rose from 1.4 billion won in 2007 to 2.1 billion won in 2010, and then fell to 1.7 billion won in 2012. For women who were exposed to ETS at work or at home, the estimated total cost of treating asthma rose from 3.0 billion won in 2007 to 3.6 billion won in 2008, and then fell to 2.5 billion won in 2012.

For coronary heart disease, the estimated total cost of treatment was 2.8 billion won in 2005 for men exposed to ETS at work and 2.1 billion-2.8 billion won in 2005 for women exposed to ETS at work or at home. For acute myocardial infarction, the estimated total cost of treatment was about 1.5 billion-1.7 billion won for men exposed to ETS at work and about 0.7 billion-1.1 billion won for women exposed to ETS at work or at home from 2007-2012.

In addition to direct medical costs of treatment, we could consider indirect costs of contracting diseases like lost days of work, costs of physical disability and the remedies for it, costs of home care and other costs. But because we have data only for the direct cost of medical treatment, we estimate only that cost.

Direct medical costs from smoking

The average cost of treating smokers is assumed to be the same as the average cost of treating those exposed to ETS, although this might not be true if smokers have more acute or more chronic conditions due to their more intense exposure to tobacco smoke. Nonetheless, we assume that any case of a disease is treated in the same way and has the same average cost of treatment regardless of its cause.

Table 11 and Table 10 show that the estimated total cost of treating lung cancer for male smokers is higher than for males exposed to ETS. And from 2007-2012 the estimated total medical cost for treating lung cancer for male smokers rose from 652 million won to 1093 million won. But because there are few female smokers in Korea, the estimated total cost of treating female lung cancer patients who are (or were) active smokers is lower than it is for males and for non-smoking females exposed to ETS. For female smokers with lung cancer the estimated total cost rose from about 160 million won in 2007 to 467 million won in 2012.

Notice that when we consider ETS exposure at work or at home for women in Table 11, lung cancer cases attributable to ETS exposure for women increase but lung cancer cases attributable to smoking for women decrease. Essentially, the calculations show that when ETS exposure becomes more common (at work or at home), it becomes a more significant cause of disease for a given number of cases, so that smoking becomes a less significant cause for the same number of cases.

The estimated total cost of treating female smokers for cervical cancer has risen from 18 million won to 60 million won, when we consider ETS exposure at work or at home. The results are barely different when we consider only ETS exposure at work.

The estimated total cost of treating COPD for male smokers has fallen from about 37.9 billion won to about 30.4 billion won during 2007-2012. For female smokers, the estimated total cost of treating COPD has fallen from about 4.3 billion won to about 2.8 billion won when we estimate the number of cases from ETS exposure at work or at home. Because there are so few reported female smokers relative to male smokers and relative to females exposed to ETS, the estimated total cost of treating female smokers is smaller than both of these alternative cases.

For asthma, costs have risen or fallen as the number of estimated cases from smoking have risen or fallen. For men, the estimated total cost of treating asthma rose from 3.1 billion won in 2007 to 5.0 billion won in 2010, and then fell to 3.9 billion won in 2012. For women who were exposed to ETS at work or at home, the estimated total cost of treating asthma rose from 0.8 billion won in 2007 to 1.4 billion won in 2008, and then fell to 1.0 billion won in 2012.

For coronary heart disease, the estimated total cost of treatment was 5.0 billion won in 2005 for male smokers and about 0.5 billion won in 2005 for female smokers. For acute myocardial infarction, the estimated total cost of treatment was about 1.5 billion-1.7 billion won for male smokers and about 0.7 billion-1.1 billion won for female smokers from 2007-2012.

Strengths, weaknesses and further research

As stated in earlier sections, survey questions about ETS exposure were self-assessed and did not ask about the frequency, duration or severity of ETS exposure, and in particular did not ask about ETS exposure both at work and at home. Self-assessed responses can be very unreliable because they depend on the accuracy of recall, emotional responses to the questions and interpretations of the wording of the questions. Likewise, the questions about active smoking were also self-assessed, and the definition of active smoking was set at a high level of daily smoking, omitting people who smoke only occasionally.

Future surveys could ask more precise questions about ETS exposure (ex., both at work and at home? how frequent? how severe?) and active smoking (ex., once a day, a few times per week, a few times per month, a few times per year). Given more precise survey questions, we could make a more precise study of the effects of ETS exposure. Also, one could also try to assess the ill effects of past smoking. Nonetheless, the current survey is an unbiased attempt to assess the prevalence of ETS exposure and active smoking in Korea. The current survey could ask more precise questions in the future if resources are available.

The costs of treating each disease in this study must rely on the average cost, even though some cases would be less or more costly than average, depending on the severity of the disease, among other factors. Data from hospitals that sums that costs for all cases could be a more accurate assessment of the cost of treating each disease. However, we would also need to know whether or to what degree the diseases were caused by active smoking and/or ETS exposure.