Abstract: An estimate of the health value of air pollution is provided in Life Ahead for orientation purposes. Air pollution in urban-industrial environments can subtract a full year or more of Well-Days of life. Air pollution from the smoking of others that is called Passive Smoking can be more harmful that other types of air pollution and subtract up to two years of Well-Days o life. Yet, this research shows that despite enormous publicity and public cost, the usual effect of air pollution on health and life is smaller than that from that potential from even modest changes in our life style habits.
Background: Air Pollution has been given enormous amount of publicity during the past several decades. Massive costs have been dedicated to the reduction of industrial pollutants, and air today in US and many world industrialized areas is cleaner than it was at any time during the past century. Yet many people still are concerned about the effect of present atmospheric pollution on their health. Although atmospheric air pollution is regarded as a largely “Non-actionable” factor of health, it was felt desirable to included some valuation of how this might effect our overall health and life in the Life Ahead Model.
Many pollutants combine in the measure of 'Atmospheric Pollution'. These include particulates of various size, sulfur dioxide, nitric oxide, carbon monoxide, dusts, and toxic metals. But relationships of these agents generally have been measured from overall correlations of each with disease and death. Particle pollution appears to have been best correlated with rates of death, and a measure of fine particle pollution called PM2.5 has been used in the study that follows. This will be far from a perfect index of the individual effects of all individual pollutants, but still probable produces a useful measure of overall harm. Air pollution in the US from industrial causes has been substantially reduced from that in prior years by environmental legislation.
The Research Study: The Life Ahead Pollution Analysis was based on a recent and very sophisticated study of Pope, et al JAMA 2002:287:1132. This study of 1.2 million US adults initiated in 1982 followed results on 500,000 individuals in 53 metropolitan areas in which Fine Particulate Air Pollution was measured. The results were risk ratio (RR) values for all-cause death, cardiopulmonary death, lung cancer death, and all other cause death associated with a measure of fine particles in the atmosphere called PM2.5.
It was found not surprisingly that pollutants in the 53 areas were about 30% lower in 1999-2000 than they were in 1979-83. The more recent range of PM values in these areas was from about 5 to 18 on the scale used. This information was adapted to Life Ahead by using values of 5 PM2.5 for “Rural”; 11 for “Suburban”, 15 for Suburban-Urban, and 18 for Urban-Industrial as categories of entry.
The Valuation in Life Ahead: The key factors used from this analysis were a risk ratio for all-cause Death of 1.06 (CI = 1.02-1.10), and a risk ratio for lung cancer death of 1.13 (CI = 1.04-1.22) for a difference of 10 units in PM. These values were translated to 1.08 and 1.17 respectively for the overall Rural-Urban-Industrial difference in PM for 13 units. The overall RR values of all-cause death for this difference of 13 PM were equivalent to that of an added Life Ahead entry of 0.9 cigarettes per day. Or by category, an equivalent of 0.2 cigarettes/day for rural, 0.6 for suburban, 0.9 for Suburban-Urban, and 1.1 for Urban Industrial closely reproduced the amounts of all-cause death described by this study.
The death rate risk ratio for lung cancer from Air Pollution was only slightly higher than that for all-cause death. In contrast the lung cancer death rate from smoking is far higher than the all-cause risk of death rate. This same lesser effect on lung cancer was noted in the research on passive smoking, the smoke of others that smoke. This suggests that atmospheric pollutants will not produce the same effects on disease was do cigarettes. Perhaps some of the harmful components of cigarettes such as carcinogenic tars that go directly into the lungs from cigarettes either drop out or are modified before intake from a usual atmosphere. The effect of pollution on lung cancer is thus modified in the Life Ahead model to agree more closely with these actually measured effects.
Life Ahead Version #3 identifies the following risks in terms of Well-Days of life for various levels of pollution as follows:
Environment Equiv Well-Days Cost vs. Well-Days Cost
Cigarettes/Day zero pollution vs Rural
Rural Area 0.2 190 Base
Rural-Suburban 0.6 400 210
Suburban-Urban 0.9 510 320
Urban-Industrial 1.1 570 380
These results show that living most a life in an urban-industrial area costs about 1 year of life in terms of Well-Days vs living in a rural area. But few US people today can earn a livelihood in a rural area. Thus the more feasible difference of living in a rural-suburban type area would cost only about 1/2 year of Well-Days. This value is far lower than the differences achievable from diet, exercise, and other lifestyle habits. Life Ahead does not now include this measure of Well-Days in its basic valuations partly because is usually is non-actionable health factor of secondary importance, and can be only a very rough quantification of risk. This effect of pollution is noted, however, in the program results. But it is useful to have some perspective about a health factor that often results in excessive and misleading publicity.
Air Pollution from Passive Smoking: Another and potentially more serious form of Air Pollution is that produced by the cigarette smoking of others. This has been a subject of the massive studies needed to overcome the hard-line opposing publicity of Tobacco Companies. Fortunately, major public recognition of this as substantially reduced our exposure to this harm to our health in recent years.
Medline now lists more than 4650 studies relating to the effects of Passive Smoking. The results are convincing and impressive. A meta-analysis or summary average result of 19 studies by Law (BMJ 1997;315:773) found that Passive Smoking produced an average risk ratio for coronary heart disease of 1.30 (CI = 1.22-1.38), and with adjustments was 1.23 (CI = 1.18-1.64). A group from the large MRFIT study showed an average risk ratio of 1.40 (CI = 0.8-2.5). Men who were exposed to co-workers but with wives that did not smoke suffered a 1.2 (CI = 0.4-3.7) and those with wives that smoked and co-workers that smoked had an risk ratio of 1.7 (CI-0.8-3.6). Another meta-analysis of 18 studies on Coronary heart disease by He, (NEJM 1999;340:920) also found an risk ratio of 1.25 (CI = 1.17-1.32). Those exposed to partners smoking 1-19 cigarettes per day had a risk ratio of 1.23, and those exposed to partners smoking 20+ per day had a risk ratio of 1.31. Men and women had similar results.
Similar results were obtained for the risk of cancer. Average all-cancer risk on women was 1.23 (CI = 1.12-1.31) for women whose husbands smoked. A higher value of risk ratio = 1.68 (CI = 1.1-2.5) was obtained by Reynolds from the Alameda, CA study. This is a sampling of much more that has been published.
An Life Ahead estimate of the cost of Air Pollution from Passive Smoking of others is:
Exposure Equiv Well-Days Cost vs. Well-Days Cost
Cigarettes/Day zero pollution vs Minimal
Minimal 0.2 190 Base
Average 0.5 350 160
Fair Amount 1.0 540 350
Quite a Bit 2.5 820 630
Two key factors are involved in the effect of Passive Smoking. First is the environment at home. Second is the environment of the work place. A non-smoking person that has a spouse that smokes is exposed 'Quite a bit'. Many non smoking persons have died of lung cancer from the long term continued smoking of a spouse. Working in an environment that includes smoking persons also can contribute. Fortunately, most work places today are large free of smoke.
In past years it was common for people to be exposed 'Quite a bit' both at home and in the workplace. This combination can produce the equivalent of smoking 2-3 cigarettes per day even though no actual smoking was done. Passive Smoking of this amount easily can subtract two years of a person's Well-Days of life. As for other Air Pollution, the Well-Days of passive smoking above minimal is provided only as a footnote in the Life Ahead Well-Days results for All Causes of Death.