Do smokers know what they are doing to their life expectancy?

By Valeria Bordone, University of Munich Department of Sociology and IIASA World Population Program

Everyone, consciously or unconsciously, formulates in their own mind a subjective survival probability– i.e., an estimate of how long they are going to live. This will affect decisions in different spheres of later life: retirement, investments, and healthy behaviors. Moreover, previous research has found that subjective survival probability is a good predictor of mortality. In fact, on average, people somehow know better than standard health measures the effect that their characteristics and their behavior have on life expectancy. It is however plausible not only to expect differences within the population in terms of survival, but also in the ability to predict their own survival.

(cc) roujo | Flickr

In a recent publication with Bruno Arpino from the University Pompeu Fabra and Sergei Scherbov from the Wittgenstein Centre (IIASA, VID/ÖAW, WU)., we presented for the first time joint analyses of the effect of smoking behavior and education on subjective survival probabilities and on the ability of survey respondents to predict their real survival, using longitudinal data on people aged 50-89 years old in the USA drawn from the Health and Retirement Study.

We found that, consistent with real mortality, smokers report the lowest subjective survival probabilities. Similarly, less educated people report lower subjective survival probabilities than higher education people. This is in line with the well-known positive correlation between education and life expectancy. However, despite being aware of their lower life expectancy as compared to non-smokers and past smokers, people currently smoking at the time of the survey tended to overestimate their survival probabilities. This holds especially for less educated people.

This graph shows the probability of correctly estimating the own survival probabilities with 95% confidence intervals, by smoking behavior and educational attainment. ©Arpino B, Bordone V, & Scherbov S (2017)

Our study suggests that in fact, education also plays an important role in shaping people’s ability to estimate their own survival probability. Whether or not they smoke, we found that more highly educated people are more likely to correctly predict their survival probabilities.

In view of the high proportion of the American population that consists of current or past smokers, a percentage that reached 77% in some male cohorts, our findings emphasize the need to disseminate more information about risks of smoking, specifically targeting people with less education.

By showing that smoking and education play together in determining how well people can assess the own survival potential, this study extends our understanding of the variability of subjective survival probabilities within a population. The fact that sub-groups within the population differently incorporate the effects of smoking into their assessment of survival probabilities may have important consequences for example on when people exit the labor market or whether they buy a life insurance, as individuals are likely to base their decisions also on their longevity expectations.

Policymakers can therefore draw some relevant conclusions from our study to design policies concerned with health and survivorship in later life. Despite the various anti-smoking campaigns and smoking restrictions, smokers may not be fully aware of the risks of smoking. In particular, educational groups seem to be differently exposed to the information that is disseminated to the public. Our study suggests that there is a need to target such information to less educated people, who are the most likely to underestimate the risks of smoking. Providing information on how survival probabilities vary by smoking behavior may not only reduce smoking but it may also increase individuals’ ability to assess their own survival.

(cc) Quinn Dombrowski | Flickr

Arpino B, Bordone V, & Scherbov S (2017). Smoking, Education and the Ability to Predict Own Survival Probabilities: An Observational Study on US Data. IIASA Working Paper. IIASA, Laxenburg, Austria: WP-17-012 []

This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

Living to age five: Reducing deadly indoor air pollution in developing countries

By Caroline Njoki, IIASA Science Communication Fellow 2017

Child mortality is high in Nigeria. For every 1000 children born, 128 deaths occur, according to the 2013 Nigeria Demographic and Health Survey report. This is one of the highest rates in Sub-Saharan Africa.

Although the Nigerian government is working hard to change the story and ensure more children live to celebrate their fifth birthday, through schemes such as free maternal and child healthcare, indoor air pollution may hinder those efforts if not addressed, research has shown.

Solid fuels and the health of children and women

“Indoor air pollution can have a severe effect on children’s health. For example, pneumonia, a major contributor of under-five mortality, will be exacerbated,’’ says Samuel Olugbemisola, a participant in the Young Scientist Summer Program who is currently working on a project to determine just how many lives could be saved by replacing solid fuels with clean ones in Nigeria.

Indoor air pollution poses a serious health risk to children and women in developing countries © Svetlana Eremina |

It is a common practice, not only in Nigeria but in many African and Asian societies, to find mothers carrying young children on their backs as they go about domestic tasks in the home. Women are likely to spend most of their time in the kitchen cooking, washing dishes, and heating water for drinking or bathing.

Cooking in rural households is done on traditional stoves where cow dung, crop straw, charcoal, and firewood are used. The smoke contains many harmful tiny particles and substances. If taken in small quantities over a long duration, this interferes with the respiratory system and can cause other health problems. In Nigeria, 80% of children under five years live in homes where wood is the main fuel used.

A 2016 report from UN Children’s Fund links the use of these solid fuels to respiratory diseases such pneumonia, asthma, bronchitis, impaired cognitive development, and cataracts among children under five years, especially in developing countries. For children and women with already weak immune systems from malnutrition, HIV/AIDS, tuberculosis or other chronic diseases, long-term exposure from indoor air pollutants can worsen the conditions.

Exposure to indoor air pollution during pregnancy and delivery can mean miscarriage, low birth weight, or children with stunted growth. A study carried out in India also associated the likelihood of developing preeclampsia (elevated blood pressure) while pregnant with long-term exposure indoor air pollutants.

Olugbemisola, in her current IIASA study, is using the Greenhouse Gas-Air Pollution Interactions and Synergies model to estimate the number of children under five years that may be prevented from dying if cleaner fuels (such as electricity and gas) are adopted.  She hopes to share her findings with policymakers in energy and health sectors, especially in the areas severely affected by indoor air pollution and under-five mortality.

Tracing and addressing the problem

Income and wealth dictate the choice of fuel used in a household. Most rural households use solid fuel for cooking owing to their low income. In urban areas, where most people do have access to electricity, they may still rely on cheaper sources of energy such as charcoal and kerosene for cooking.

Making other cleaner forms of energy available and affordable is one way of reducing indoor air pollution (CC) Harsha K R

“Making electricity and gas available and affordable to households should be seriously prioritized by the government as a critical intervention to improve the situation. Currently, only 56% of households in Nigeria have access to electricity yet the country exports to neighboring countries such as Ghana and Benin,” says Olugbemisola.

Use of solid fuels is highest (at 98%) in the northeast region of the country, a survey by Nigeria’s National Bureau of Statistics revealed. This region also has high illiteracy, poverty, and rates of early child marriage. “Women with low or basic education lack adequate knowledge and information to enable them make informed choices as regards to maternal health, family planning, design or location of the kitchen including choice of cooking fuel”, says Olugbemisola.

She proposes innovative communication strategies to reach out to women, particularly in rural and remote areas with little or no education to raise awareness on the topic. The methods could include the use of performing arts, television and radio, and pamphlets prepared in vernacular languages to be made available at health facilities or distributed by community health workers.

Another area for improvement is the location and design of the kitchen. In most rural settings, the kitchen is either part of the main house or built separately but urban populations living in informal settlements usually occupy one room that doubles up as the sleeping and kitchen area. Poor ventilation traps the smoke and increases the concentration of tiny particles. Pollution could be reduced by installing chimneys, switching to improved cooking stoves and better ventilation to allow clear air to circulate in the kitchen.

Successful development and implementation of these interventions will help to see more children living to celebrate their fifth birthday.


Agrawal S & Yamamoto S. (2015). Effect of indoor air pollution from biomass and solid fuel combustion on symptoms of preeclampsia/eclampsia in Indian women. Indoor Air 25: 341-352

Samuel Gbemisola W. (2016). Underlying and Proximate Determinants of Under-five Mortality in Nigeria: Understanding the Pathways of Influence. Covenant University, Nigeria. PhD Thesis.

Samuel Gbemisola W, Ajayi Mofoluwake P, Odowu E & Ogundipe Oluwatomisin M (2016). Levels and Trends in Household Source of Cooking Fuel in Nigeria: Implications on Under-five Mortality. Health Science Journal 10:4

This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.


Marriage or cohabitation means a longer and healthier life

By Dimiter Philipov, IIASA World Population Program

Since the middle of the 19th century researchers have known that married men and women live longer than the unmarried: it is an inference as stable as a natural law. My colleague at IIASA, Sergey Scherbov and I supported its validity with a study in the 21st century, extending the pattern to encompass cohabiting. We also showed that people who have a partner are healthier than those without.

Across 16 European countries, partnered women aged 50 will outlive single women by 1.4 years on average before reaching age 80. For the men this difference is considerably larger: 4 years. Partnered people also have more years with healthy life (i.e., without disabilities) when compared to the singles: for women this gain is 5 years and for the men it is nearly 8 years. In general, partnership is more beneficial for the men.


© Pretoperola | Dreamstime

What makes living with a partner so important for a longer life and better health? An important advantage of living with a partner is that the partner can provide emotional, economic, social, and physical support in everyday life and in case of illness. This advantage is known as the protective effect of marriage. Over a period of 160 years causes of death have changed and the conditions of life and health have changed, yet the protective effect of marriage remains. In contemporary living arrangements cohabitation frequently replaces marriage but it has the same protective effect.

We expected single people to lack the protective effect of marriage, in other words, singles are expected to have poorer health. In addition, each one of the single sub-groups (i.e., never married, widowed, and divorced/separated) is subject to different reasons for poorer health than partnered people. For example, the never-married might have a disability that prevents them from finding a partner; widowed people are likely to lead the lifestyle of their late partner (diet, exercise, smoking, economic conditions, etc.) and are therefore more likely to suffer from the same disease that ended their partner’s life; divorces can be due to increased disability in either one of the partners.

We carried out international comparisons among the 16 European countries and found substantial diversity between countries in Western and in Eastern Europe. Populations in Eastern Europe have shorter lives, shorter healthy lives, and a longer time spent with disabilities compared to those in Western Europe. These differences are greater for single people than for partnered people; for example single men in Slovakia live only 7.4 years free of disabilities in the interval from 50 to 80 years, while in Sweden they enjoy nearly 20 years of healthy life.

The Nordic countries are leading with respect to length of healthy life and small differences between partnered and single people. The protective effect of marriage or cohabitation seems to be small in these countries. We believe this is due to the strong social policies that prevail in these countries.

What can we expect for the future? Statistical data indicate that the proportion of single people above age 50 and especially of single men increases with time. Hence the proportion of those who experience disabilities and ill-health will rise unless policies are put in place to help relieve these adverse effects.

Reference: Philipov D & Scherbov S (2016). Differences by union status in health and mortality at older ages: Results for 16 European countries. Demographic Research, 35: 535-556. 

This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

Modeling Vienna’s traffic: air pollution and health

By Anneke Brand, IIASA science communication intern 2016.

Accidents, lane closures, and congestion all affect the flow of road traffic and harmful emissions from vehicles. Live traffic data allow congestion to be detected more accurately and provide a more precise overview of vehicle emissions at different times and places. In his project for the Young Scientists Summer Program (YSSP), Fabian Heidegger investigates how road traffic affects air pollution in cities, using Vienna and surrounding areas as a case study.

Air pollution is a major problem in Europe and globally. Health impacts of air pollution include a range of respiratory and cardiovascular diseases. “10-20% of Europe’s urban population is exposed to excessive levels of nitrogen dioxide (NO2), along with several other air pollutants. NO2 pollution is highest along busy roads. Technical measures have so far often been circumvented, so cities are looking for other measures to reduce the pollution load. Traffic management has therefore gained interest as a way to reduce air pollution,” says Jens Borken-Kleefeld, Heidegger’s study leader at IIASA.

To calculate the amount of air pollution that cars and other vehicles release into the air, researchers use models that apply various sets of data: traffic networks, where and how far people drive, and emission factors of different vehicle categories. Input data for the model may include how many people live in a certain area, how many of them use cars, where they normally drive, and how many grams of pollutants (such as nitric oxide and NO2 gases) their type of cars emit per kilometer.

© Radub85 |

Inner city Vienna. © Radub85 |

Most of these models rely on average daily traffic data. For Heidegger’s YSSP project, which is related to his PhD work at the University of Natural Resources and Life Sciences  in Vienna, he is incorporating real-time data, measured every five minutes, into a traffic simulation model developed by Intelligent Transport Systems Vienna Region. A set of detectors in and around the city record the number and speed of vehicles. In addition, location data from the taxi fleet is incorporated into the traffic simulation. Heidegger can therefore immediately identify adverse traffic conditions like stop-and-go traffic, which has a high impact on emissions. This allows for a more accurate calculation and can help design traffic interventions for improving both traffic flow and air quality.

“In the case of a road closure, local emissions will obviously be lower at the specific road but total emissions for the area could be higher than before when drivers use alternative, longer routes or end up in stop-and-go traffic,” says Heidegger.

In order to understand how these diversions and the displacement of pollutants can affect overall emissions, Heidegger will first determine the emissions per street section, and second, what the effects are of diversions from day-to-day traffic patterns. Together with researchers from the Air Quality and Greenhouse Gases Program at IIASA, Heidegger plans to assess the impact of different intervention scenarios, for example an environmental zone in the city, where only modern cars will be allowed to enter. In a second scenario he will look at the effect of people commuting to Vienna, and a third scenario will explore the consequences of expanding pedestrian zones. The researchers hope that this study will better their understanding of the potential of traffic management to reduce air pollution.


More information

Air Pollution Policy Review 2011-2013


AIR Program

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.


Is it worth it to bike to work?

By Katherine Leitzell, IIASA science writer and press officer (and cyclist)

In May over 50 IIASA staff members took part in the Austrian Bike to Work month (Osterreich Radelt zur Arbeit), logging 11,681 kilometers riding to and from the institute in Laxenburg. The institute took fifth place in Austria in terms of kilometers ridden, and first place in Lower Austria.

According to the Austrian initiative’s calculations, this effort translated into saving over 1900 kg of CO2 emissions, or on average 36 kg per person—which is approximately 4% of an average Austrian’s monthly CO2 emissions. However, this calculation assumed that each of the IIASA cyclists would have been otherwise driving alone in a car. Since many people ride the bus or take public transport if they’re not biking, the actual emission savings from our cycling efforts in May were in fact much less. In fact, since buses and trains run anyway, cycling to work may make no impact whatsoever on emissions of air pollution and greenhouse gas emissions. Does that mean it’s not worth it to make the effort?

© Katherine Leitzell | IIASA

The author’s route to the office. © Katherine Leitzell | IIASA

IIASA researcher Jens Borken has analyzed the impacts that our daily travel has on the individual climate footprint. Personal mobility—all kinds of travel—make up about one third of the average European’s annual greenhouse gas emissions: the rest come from consumption choices and household heating and energy use. Of the carbon footprint from mobility, he says, commuting generally only makes up 10-15% of that. The largest part of the mobility budget is related to shorter and longer distance leisure travel, and in particular from air travel.

“From a quantitative perspective, the climate benefit of riding your bike is small, but it can be one step on a path to a low-carbon lifestyle.” says Borken. “As researchers who work on climate change, riding a bike to work (and possibly further) brings one piece of our lives in line with the message that avoiding fossil fuel consumption is imperative. I think that that is valuable. But it need not stop there. Travel choices are important, especially for longer distances, but so are consumption choices and energy usage and efficiency.”

Charlie Wilson, a researcher at the Tyndall Centre and IIASA, recently won a grant from the European Research Council to explore the role that social influence plays in spreading climate innovations. He says, “As social animals we are strongly influenced by what others do; as psychological beings we strive for consistency. Changing a behavior – like cycling to work – may have a small impact in isolation. But this impact is magnified through positive spillover effects. Others may imitate or be inspired by our commitment to cycling. And this change in behavior may also strengthen the pro-environmental aspects of our own self-identity, reducing dissonance between our work and domestic lives, and supporting further changes in behavior.”

Of course there are benefits of cycling beyond the environmental or climate impact, which is one reason that once they start, many people keep it up. Cycling regularly can save money compared to commuting by car or public transport, and like any regular form of exercise, it can bring health benefits and stress relief. It also brings autonomy and flexibility compared to public transport.

Borken points to research showing that the health benefits of cycling outweigh the exposure to air pollutants  that a cyclist might experience on busy city streets—and that automobile drivers are exposed to even higher levels of air pollution within their cars. Cyclists who ride to IIASA, located about 15km outside Vienna, probably have even lower exposure to air pollution riding along tree-lined bike paths.

“Riding to work in the morning wakes me up and prepares me for the day ahead. Even if windy and challenging, the return in the evening calms the mind while riding with colleagues at a pace that allows us to chat at the end of a busy workday. It’s truly one of the best ways to get exercise and stay healthy – good for the heart, good for the environment and, most importantly, good for the soul,” says Michaela Rossini, manager of the IIASA library and a co-organizer of Bike to Work Month at the institute.

For some staff members, one side benefit of cycling to IIASAis the beautiful sunrise along the Danube River ©Michaela Rossini | IIASA

For some staff members, one side benefit of cycling to IIASA is the beautiful sunrise along the Danube River ©Michaela Rossini | IIASA


Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.