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Highlights • Key differences in indicator methodology EU vs USA related to air pollution mortality. • Revisiting the hypothesis on a harvesting effect from air pollution. • Loss of victims’ lifetime expectations explored with Lexis diagram. • Cost estimates of lifeyear approach vs. fatality approach.
Abstract Making up for air pollution related mortality and accounting for the number of deaths has become an important environmental indicator in its own right, but differences across the Atlantic over how to account for these are making it difficult to find common ground in climate policy appraisals, where co-benefits from reducing air pollution of fossil fuels is to be factored in. This article revisits established quantification methodologies for air pollution related mortality applied by government agencies in USA and EU. Demographic lifetables are applied to explore uncertainties over latency periods and the number of affected victims. These lifetable simulations are based on WHO consensus estimates for the mortality risk ratio related to long-term exposures and suggest an average loss of life expectancy of 9–11 years for an annual air pollution exposure increase of 10 ugPM 2.5 /m3. With a common OECD base value approach the air pollution costs related to fossil fuels are found to be about 3 times lower with EU versus US methodology.
Recent years has seen increased interest in including the co-benefits of reduced air pollution from fossil fuels in appraisals of climate and energy policies (OECD, 2014 ; World Bank and IHME, 2016). For emerging economies, with levels of air pollution from fossil fuels subject to less stringent regulations, recent studies for Mexico, South Africa and India underline that energy transitions providing deep reductions in conventional air pollutants are offering substantial health and welfare benefits against the costs of climate mitigation policy (Barker et al., 2010; Eto et al., 2013 ; Thambiran and Diab, 2011). China probably represents the most compelling case, as has been pointed out by many (World Bank, 2007). The benefits from improved air quality could well offset the greater part of mitigation costs, with 75–85% for Europe as a lower bound conservative estimate (cf. Schucht et al., 2015).
There are considerable challenges in accounting appropriately for the lives lost from air pollution and in monetizing benefits from reductions in fossil fuels. While the potential significance was highlighted over 20 years ago by IPCC (1995:215), an international consensus on the underlying health science has been accomplished only recently (WHO, 2013). Bringing this knowledge base to good use is nevertheless complicated by government agencies in USA and EU having adopted different methodologies. Many energy transition studies and even studies directly addressing air pollution, that are making use of cost estimates as indicators, pay scant attention to the issues involved (Pascal et al., 2013).
The objective here is to analyze and explore the different approaches and rationales in USA and EU in view of present knowledge on air pollution related mortality, more specifically the numbers, age profiles and years of life lost by air pollution victims. The analysis places methodological differences with regard to co-benefits in perspective and should be of interest to all readers and users of studies with air pollution deaths included. It also aims to inform international institutions looking for common ground in accounting for air pollution deaths from fossil fuels.
2. A harvesting effect of air pollution and its implications
Cost-benefit analysis in USA relating to air pollution proceeds from a standard approach whereby abatement measures preventing premature mortality are considered according to the number of statistical fatalities avoided, which are appreciated according to the value of statistical life (VSL) (presently USD 7.4 million) (IEc, 2010).
In contrast, and following recommendations from the UK working group on Economic Appraisal of the Health Effects of Air Pollution ( EAHEAP, 1999), focus in Europe has been on the possible changes in average life expectancy resulting from air pollution. The point of departure has been indications from air pollution episodes that victims are mainly elderly citizens in poor health (e.g. Schimmel and Murawski, 1976:318). Chilton (2004) provides the following non-technical explanation of the phenomenon; “for some people in their 70’s and 80’s with existing heart or lung disease, the unusually high level of pollution on a bad air day can put so much extra stress on their breathing, that their heart fails and they cannot be revived. Often these people are not expected to live very much longer anyway, but a bad air day can bring their death forward. If the bad air day had not occurred, they could have lived a few weeks or months longer, although this time would have been spent in their existing poor state of health”.
Consequently government agencies in Europe, including the European Commission, apply a methodology for costing of air pollution that is based on accounting for lost life years, rather than for entire statistical lives as is otherwise customary in economic appraisals in Europe. Whereas the average traffic victim, for instance, is mid-aged and likely to lose about 35–40 years of life expectancy, pollution victims are believed to suffer significantly smaller losses of perhaps only one or a few years (EAHEAP, 1999:64; Friedrich and Bickel, 2001). To avoid overstating the benefits of air pollution control, these are treated as proportional to the number of life years lost.
The quintessence of these assumptions is the hypothesis of a harvesting effect from air pollution (first proposed by Schimmel and Murawski, 1976:317), according to which “the increased mortality associated with higher pollution levels is restricted to very frail persons for whom life expectancy is short in the absence of pollution” (Zeger et al., 1999:171). The harvesting hypothesis has been disputed by analysis showing that, at least for the immediate months following an air pollution episode, there is no netting out of mortality rates, while being unable to account for any longer term displacement (Schwartz, 2000; Schwartz, 2001 ; Zeger et al., 1999).
In Europe the specific number of life years lost as a result of changes in air pollution exposures are estimated based on lifetable methodology (see Section 3 on Materials and methods), and monetized with Value-Of-Life-Year (VOLY) unit estimates (Holland et al., 1999 ; Leksell and Rabl, 2001). The theoretical basis is a life-time consumption model according to which the preferences for risk reduction will reflect expected utility of consumption for remaining life years (Hammitt, 2007; OECD, 2006:204).
Where the European Commission in sensitivity calculations has considered the number of statistical fatalities, the air pollution specific VSL applied is reduced by 30% to reflect the value of avoiding merely ‘deaths brought forward’ among seniors (based on a panel recommendation (European Commission, 2001) and studies suggesting that the willingness-to-pay for risk reductions peaks at mid-age (Aldy and Viscusi, 2007)). In USA proposals from the Office of Management and Budget (OMB) for a comparable approach with reductions for elderly led to a public outcry against the use of a ‘senior death discount’ and the passing of a resolution in Congress abolishing application by federal agencies (WP, 2003). Concerns are underpinned by economists maintaining that life is a more precious good at older age (Krupnick, 2007 ; Krupnick et al., 2005). The Science Advisory Board of the US-EPA has concluded that the existing economics literature does not provide clear theoretical or empirical support for using different values for mortality risk reductions for differently-aged adults, nor does it support a constant value of a statistical life year (cf. US-EPA, 2007; NCEE, 2010:12).
Air pollution costs, as a result of these conventions, are appreciated entirely differently across the Atlantic.
In Europe VOLY values have been deducted from a traffic-related VSL under the assumption that a mid-aged traffic victim loses approximately 35–40 years of life-expectancy. The much lower VSL values customary in Europe (presently €2.2 million) add decisively to the differences. Chilton (2004) was the first study to elicit directly the willingness-to-pay expressed in VOLY’s in an air pollution context. The results from this and other studies with wider geographical coverage (Alberini et al., 2006; Desaigues et al., 2011 ; Markandya et al., 2004) have been interpreted to suggest that VOLY estimates correspond relatively well to estimates derived from a European traffic-related VSL (OECD, 2006:206), when VSL is considered to represent the discounted1 stream of values relating to life years lost by traffic victims.
Teelo888 on July 4th, 2017 at 15:25 UTC »
To give some perspective, the WHO recommended exposure limit of PM2.5 is an annual mean of 10ug/m3.
Washington D.C.: 9ug/m3 PM2.5 (most major U.S. cities are around 5-9ug/m3)
Riyadh, Saudi Arabia: 156ug/m3 PM2.5
Delhi, India: 122ug/m3 PM2.5
Doha, Qatar: 93ug/m3 PM2.5
Beijing, China: 85ug/m3 PM2.5
Abu Dhabi, UAE: 56ug/m3 PM2.5
This is why it frustrates me to hear politicians convincing the average Joes of this country that we need to begin repealing environmental protection legislation to deregulate (just for the sake of deregulating). In the U.S., many of us don't realize how good we have it in terms of clean air and clean water.
Source for the above data: www.who.int/phe/health_topics/outdoorair/databases/cities/en/ (click on ambient outdoor air pollution database on the right side)
agumonkey on July 4th, 2017 at 14:40 UTC »
Allow me to ask how common it is for people to "filter" air around them, whatever the mean (pumps, filter, plants, ....). Are there detailed maps for this (so one can see what kind of particles are in a certain area) ?
PM_ME_OLD_PM2_5_DATA on July 4th, 2017 at 14:07 UTC »
The headline here is consistent with several previous studies, and is not really surprising. (Edit: for example, this study from MIT identifies 200,000 early deaths from air pollution each year in the US; one of its authors notes that "a person who dies from an air pollution-related cause typically dies about a decade earlier than he or she otherwise might have.")
A lot of people think of air pollution as only causing things like asthma, but there is evidence linking it to damage throughout the cardiovascular system, and even beyond. For example:
asthma bronchitis bronchiolitis emphysema allergies lung cancer birth defects stroke COPD dementia autism ADHD, mental illness depression 1, 2,3(last two bullets courtesy of u/potpourris)
Further, air pollution has effects even in healthy people; these include:
decreased lung function susceptibility to diseases in general loss of lung capacity accelerated aging of the lungs reduced IQ (from prenatal exposure)Even in healthy young men, all it took was very short-term exposure to cause an 11% decrease in white blood cells and a 32% increase in C-reactive protein (a marker of inflammation).
For some related recent research, here is a new study out of Harvard finding that even when particulate levels are within US standards, there are still tens-to-hundreds of thousands of early deaths every year.
Edit #2: I think my comment came out more alarming than I meant it to. On a population level, yes, we should all be more concerned about air pollution. But for any given person, it's just one of many risk factors to weigh, and it's one that's necessarily entangled with confounders (income, socioeconomic status, health habits, etc.); the cause-and-effect relationship is not always clear. People who are predisposed to asthma or heart disease may see short-term effects from air pollution, but if you're otherwise in good health you really shouldn't worry too much -- particularly because there's not that much you can do. I mean, try not to, like, live right next to a freeway if you can avoid it, and don't drive more than necessary.
This is my field of research (air pollution and human health), and I personally know many scientists who do things like move their family to LA or Pittsburgh (for university research opportunities), or spend a year in China or India on a field campaign. They're obviously aware of the risks, but they're also, you know, living their lives. There's a lot we still need to learn about air quality and human health . . . while I think we all need to be more aware of the issue, I'd hate to think that I caused anybody unnecessary worry.