Article in the New England Journal of Medicine: Ambient Particulate Air Pollution and Daily Mortality in 652 Cities

A new international study by the The MCC Collaborative Research Network with CERH researchers Professor Jouni Jaakkola, Docent Yuming Guo and Postdoctoral researcher Niilo Ryti confirms links between exposure to urban pollution and mortality risk. A multi-country analysis shows an increased risk of mortality in the short-term after exposures to even small concentrations of urban air pollution. The analysis showed exposure to even a tiny amount of urban air pollution can immediately increase the risk of mortality.

In what is the largest epidemiological assessment to date on the short-term effects of air pollution, the researchers gathered time series data from 652 cities from 24 countries within the period 1986-2015, and applied sophisticated statistical methods to compare daily mortality with levels of particular matter. They found that, on average, a 10 microgr/m3 increase in inhalable (PM10) and fine (PM2.5) particles is associated with an increase in mortality of 0.44% and 0.68%.

The database has been collected within the Multi-Country Multi-City (MCC) Collaborative Research Network, an international collaboration studying the association between environmental stressors, climate change and health.

Professor Jaakkola underlines the consistency of the adverse effects in different populations in varying climatic conditions: “The associations between PM concentration and mortality were positive in all 24 countries, although the strength of association varied. The effect estimates for The Helsinki Metropolitan Area and other parts on Northern Europe were among the smallest.”

There has been a steady decline in ambient particulate concentrations in Helsinki Area over the past three decades, because of improved clean technology in vehicles and energy production. In spite of the decline in particulate levels, Jaakkola claims, that further reduction of air pollutions is needed: “First, increase in mortality is only the most serious effects in the wide spectrum of adverse effects. For example, our recent findings showed an association between air pollution levels in pregnancy and the risk of preterm birth, which predicts development of several chronic diseases later in life.”  Reduction in particulate air pollution by reducing use of fossil fuel yields a double dividend: “By reducing air pollution-related health effects, we are also mitigating climate change by concurrently reducing carbon dioxide emissions.”

The article was published in the New England Journal of Medicine on August 22, 2019. The article is available at: 

A video summary of the article is available at

Liu C, Chen R, Sera F, Vicedo-Cabrera A, Guo Y, Tong S, de Sousa Zanotti Stagliorio Coelho M, Hilario P Saldiva N, Lavigne E, Matus Correa P, Valdes Ortega N, Osorio Garcia S, Pascal M, Stafoggia M, Scortichini M, Hashizume M, Honda Y, Hurtado M, Cruz J, Nunes B, Teixeira JP, Kim H, Tobias A, Íñiguez C, Forsberg B, Åström C, Ragettli MS, Guo YLL, Chen BY, Bell ML, Wright CY, Scovronick N, Garland R, Milojevic A, Kyselý J, Urban A, OrruAaron H, Indermitte E, Jaakkola JJK, Ryti NRI, Zanobetti A, Schwartz J, Cohen A, Gasparrini A, Kan H. Ambient Particulate Air Pollution and Daily Mortality in 652 Cities. N Engl J Med 2019; 381:705-715. DOI: 10.1056/NEJMoa1817364. 

More information:
Jouni J. K. Jaakkola, Professor of Public Health, Director,
Center for Environmental and Respiratory Health Research (CERH), University of Oulu
Email: jouni.jaakkola (at), tel. +358 40 6720 927

Last updated: 6.9.2019