Swedes harmed by air pollution

Every year 7600 people in Sweden die prematurely due to nitrogen dioxide and particulate matter, with an annual cost to society of at least 5.3 billion euro.

Even though Sweden has one of Europe’s lowest levels of air pollution, each year about 7600 people die prematurely due to exposure to air pollutants, primarily nitrogen dioxide and particulate matter, according to a new study by the Swedish Environmental Research Institute and Umeå University. Each death corresponds to a loss of approximately eleven years of life, and the annual cost to society is conservatively estimated to amount to at least SEK 56 billion (€ 5.3 billion) for the year 2015.

The study focussed on nitrogen dioxide (NO₂) and particles in the size categories 2.5 and 10 microns or less (PM_2.5 and PM₁₀) and only on regional and urban background concentrations, i.e. roadside concentrations were not addressed.

It was found that most of the PM_2.5 at urban background stations is transported over long distances, largely from emission sources outside of Sweden. Road dust resulting from the use of studded tires is the largest source of locally generated PM₁₀. The high levels of NO₂ are caused largely by local traffic emissions, with an increased proportion of diesel vehicles exacerbating the problem.

Despite the fact that the overall level of air pollution in Sweden seems to be diminishing, the study shows that total population exposure to air pollution is roughly the same as in previous surveys. This is explained by ongoing urbanisation – as more people move to the cities, a greater number are exposed to higher levels of air pollution – and by a growing population.

Nearly the entire Swedish population was exposed to concentrations below the EU air quality annual mean limit values, and 97 per cent, 78 per cent and 77 per cent respectively were exposed to concentrations below the stricter national Swedish environmental objectives for NO₂, PM₁₀ and PM_2.5.

“New studies on the impact on mortality indicate that the local effects of traffic pollution have been underestimated, so we now attribute more deaths to pollution at lower levels of exposure,” said Bertil Forsberg, Professor of Environmental Medicine at Umeå University.

Of the total 7600 annual premature deaths, approximately 3600 are associated with exposure to regional background concentrations of PM2.5. Locally emitted particles (road dust, wood smoke and exhaust particles) are assumed to have different effects on mortality, but the researchers said they faced problems identifying specific exposure-response functions. Acknowledging this uncertainty, it was estimated that particles from local wood burning cause more than 900 deaths per year, and that particles from road dust cause around 215 deaths per year.

According to the study, the impact on mortality from locally emitted vehicle exhaust emissions, including particles, is best indicated by exposure-response functions for within-city gradients in NO₂, which could also include the effects of NO₂ itself. Using this approach, it was estimated that vehicle exhaust emissions cause approximately 2850 deaths per year.

The socio-economic costs of mortality were estimated by calculating the number of life years lost per fatality (which was approximately 11 years) and multiplying these figures by a value of €40,000. The authors point out that this is a very conservative estimate, so they also did a sensitivity analysis in which they instead used values for a lost statistical life (VSL). If an official Swedish VSL of SEK 23 million is used, the socio-economic costs of air pollution in Sweden in 2015 would be more than three times higher (SEK 185 billion), and if a recent Danish VSL is used instead the costs would rise even more, to SEK 294 billion.

Christer Ågren

The study “Quantification of population exposure to NO₂, PM_2.5 and PM₁₀ and estimated health impacts” (June 2018). IVL Swedish Environmental Research Institute report No. C317. Available at: https://www.ivl.se/english/startpage/top-menu/pressroom/press-releases/p...