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Ozone is associated with cardiopulmonary and stroke emergency hospital visits in Reykjavik, Iceland 2003--2009
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. (Arcum)
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. (Arcum)
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2013 (English)In: Environmental health, ISSN 1476-069X, E-ISSN 1476-069X, Vol. 12, no 1, 28- p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Air pollution exposure is associated with hospital admissions and emergency room visits for cardiopulmonary disease and stroke. Iceland's capital area, Reykjavik, has generally low air pollution levels, but traffic and natural sources contribute to pollution levels. The objective of this study was to investigate temporal associations between emergency hospital visits and air pollutants ozone (O3), nitrogen dioxide (NO2), and particulate matter (PM10) in the Icelandic capital area.

METHODS: We constructed a time series of the daily number of adults who visited the emergency room, or were acutely admitted for stroke or cardiorespiratory causes to Landspitali University Hospital 1 January 2003 -- 31 December 2009 from the hospital in-patient register. We used generalized additive models assuming Poisson distribution, to analyze the daily emergency hospital visits as a function of the pollutant levels, and adjusted for meteorological variables, day of week, and time trend with splines.

RESULTS: Daily emergency hospital visits increased 3.9% (95% confidence interval (CI) 1.7-6.1%) per interquartile (IQR) change in average O3 the same and two previous days. For females, the increase was 7.8% (95% CI 3.6-12.1) for elderly (70+), the increase was 3.9% (95% CI 0.6-7.3%) per IQR increase of NO2. There were no associations with PM10.

CONCLUSIONS: We found an increase in daily emergency hospital visits associated with O3, indicating that low-level exposure may trigger cardiopulmonary events or stroke.

Place, publisher, year, edition, pages
BioMed Central, 2013. Vol. 12, no 1, 28- p.
Keyword [en]
Air pollution; Stroke; Cardiopulmonary; Cardiac; Cardiovascular; Hospital admissions; Emergency room visits
National Category
Environmental Health and Occupational Health
URN: urn:nbn:se:umu:diva-68042DOI: 10.1186/1476-069X-12-28ISI: 000318251500001PubMedID: 23566138OAI: diva2:615559
Available from: 2013-04-11 Created: 2013-04-11 Last updated: 2016-05-23Bibliographically approved
In thesis
1. Health effects of air pollution in Iceland: respiratory health in volcanic environments
Open this publication in new window or tab >>Health effects of air pollution in Iceland: respiratory health in volcanic environments
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Air pollution has adverse effects on human health. The respiratory system is the most exposed and short-term changes in air pollution levels have been associated with worsening of asthma symptoms and increased rates of heart attacks and stroke. Air pollution in cities due to traffic is the major concern, as many people are exposed. However, natural sources of air pollution such as natural dust storms and ash from volcanic eruptions can also compromise human health. Exposure to volcanic eruptions and other natural hazards can also threaten mental health. Air pollution has not been extensively studied in Iceland, in spite of the presence of several natural pollution sources and a sizeable car fleet in the capital area.

The aim of this thesis was to determine if there was a measurable effect on health which could be attributed to air pollution in Iceland. This aim was pursued along two paths; time series studies using register data aimed to determine the short-term association between daily variation in air pollution and on one hand daily dispensing of anti-asthma medication or the daily number of emergency room visits and emergency admissions for cardiopulmonary causes and stroke. The other method was to investigate if exposure to the Eyjafjallajökull volcanic eruption was associated with adverse health outcomes, either at the end of the eruption, or 6 months later.

In paper I time series regression was used to investigate the association between the daily number of individuals who were dispensed anti-asthma medication and levels of the air pollutants particle matter with an aerodynamic diameter less than 10 μm (PM10), nitrogen dioxide (NO2), ozone (O3), and hydrogen sulfide (H2S) during the preceding days. For the study period 2006-9, there were significant associations between the daily mean of PM10 and H2S and the sales of anti-asthma medication 3 to 5 days later. Giving the exposure as the highest daily one-hour mean gave more significant results. Air pollution negatively affected the respiratory health of asthma medication users, prompting them to refill their prescriptions before they had originally intended to.

In paper II the main outcome was the number of individuals seeking help at Landspitali University Hospital emergency room for cardiopulmonary disease or stroke. Time series regression was used to identify the lag that gave the best predictive power, and models were run for data for 2003-9 pollutants PM10, NO2, and O3. O3 was significantly associated with the number of emergency hospital visits the same day and two days later in all models, and both for men, women and the elderly. Only emergency hospital visits of the elderly were associated with NO2, and there were no associations with PM10.

In paper III the aim was to investigate if the health effects of PM10 were affected by the addition of volcanic ash from the 2010 eruption of Eyjafjallajökull and 2011 eruption of Grímsvötn to PM10 in the capital area. Time series regression of emergency hospital visits and PM10 before and after the Eyjafjallajökull eruption showed that the effect tended to be higher after the eruption, but the results were not significant. Analysis with a binary indicator for high levels of PM10 from volcanic ash and other sources showed that volcanic ash was associated with increased emergency hospital visits. There were no associations with high levels of PM10 from other sources.

In paper IV, the health of the population exposed to the ongoing eruption of Eyjafjallajökull in 2010 was investigated thoroughly. Lung function in adults was better than in a reference group from the capital area, though many reported sensory organ irritation symptoms and symptoms of stress and mental unhealth, especially those with underlying diseases.

Paper V report the results from a questionnaire study which was carried out six months after the Eyjafjallajökull eruption. The study population comprised a cohort of south Icelanders exposed to the eruption to varying degrees and a reference group from north Iceland. Respiratory and eye symptoms were much more common in south Icelanders than in the reference group, after adjusting for demographic characteristics. Mental unhealth rates had declined considerably.

In the studies, we found that urban air pollution and natural particles have short-term effects on anti-asthma medication dispensing and emergency room visits and hospital admissions. Exposure to natural particles in the form of volcanic dust was associated with increased respiratory symptoms in a very exposed population. There were indications that volcanic ash particles were associated with increased emergency hospital visits in the following days.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2014. 82 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1659
Respiratory health, air pollution, volcanic ash, epidemiology, hydrogen sulfide.
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Research subject
Epidemiology; Public health
urn:nbn:se:umu:diva-89153 (URN)978-91-7601-082-2 (ISBN)
Public defence
2014-06-13, Triple Helix, Samverkanshuset, Umeå Universitet, Umeå, 13:00 (English)

Statement of collaboration

This thesis and the work in it have been produced in collaboration between University of Iceland and Umeå University. The thesis was issued and defended at both institutions. Responsible

Available from: 2014-05-23 Created: 2014-05-23 Last updated: 2016-08-17Bibliographically approved

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