Extreme temperatures and air pollution increase mortality

The University of Oulu’s Center for Environmental and Respiratory Health Research (CERH) focusses its research on the health impacts of global change. Climate change and traditional air pollutants are in a key role.

At the beginning of August, news media covered an international study according to which deaths caused by high temperatures would increase in Finland by up to 240 per cent between 2031 and 2080, if the fight against climate change is unsuccessful. The Finland-based Center for Environmental and Respiratory Health Research (CERH) participated in the study.

“This is the most weighted part of our activities,” says Jouni Jaakkola, Director of CERH and Professor of Public Health. “We are part of an international consortium, which aims to predict the health impacts of climate change in the light of different climate change scenarios. We can have an impact on the fight against climate change and adapting to it.”

If the milder scenario comes to be and adaptation to climate change is successful, heat-related deaths would rise in Finland by six per cent. “At the equator, for example in Columbia, the death rate would increase in the best-case scenario by 23 per cent. If both the fight against climate change and adaptation to climate change fail, the death rate will grow by 2,000 per cent. It can be deduced that the effects follow the same trend with diseases and sudden bouts of illness.

Finland already has documented evidence from the summers of 2003 and 2010, which were extremely hot. During those summers, cardiovascular (related to heart and blood vessels) and respiratory (related to breathing) deaths increased in the oldest age group. Cardiovascular causes pf death included strokes and arrhythmias, while respiratory ones included for example, chronic obstructive pulmonary disease and asthma.

“In hot weather, a person’s heat dissipation system and circulatory system are in overdrive. Pressure is exerted on the heart and via circulation to, for example, blood flow in the brain.

On the other hand, also extreme cold temperatures tax our health. We know that cold temperatures cause our blood pressure to rise and increase the risk of sudden death especially for people diagnosed with coronary artery disease. Asthmatics, in turn, get more symptoms in very cold and hot weather.


The carbon economy increases both greenhouse gases and air pollution

Heat-related deaths are the primary effects of climate change resulting directly from its manifestations, such as extreme weather phenomena. Change to the ecosystem will also result in secondary effects. A change like this could be, for example the intensity and length of the pollen season.

“We carry out basic research on the effects of pollen on mortality, and we have preliminary observations that indicate that pollen levels are linked to cardiovascular and respiratory deaths,” Jaakkola explains. The observations are on alder pollen; previously mortality has been researched only in relation to hay pollen in the Netherlands.

A possible reason for this is the systemic inflammatory reactions caused by pollen. “These are recognised already, and pollen is known to increase asthma attacks. It is also possible that pollen binds with fine particles and this results in a cumulative effect.”

In addition to nitrogen oxides, sulphur dioxide and ozone, fine particles are the most common air pollutants. Climate change may increase their impact: there is already some evidence that hazards caused by pollutants increase quite a bit in extreme temperatures. In spite of this, the connection between climate change and air pollution is more so in that common factors, in particular, combustion engine traffic, increase both pollution and greenhouse gases.


Even short-term exposure to air pollutants is hazardous

Strong evidence has accumulated on the health impacts caused by air pollution. “Even short-term exposure to fine particles, nitrogen oxides and ozone is enough to increase respiratory, cardiovascular and cerebrovascular (related to blood flow in the brain) deaths. Inflammatory reactions are once again one of the mechanisms,

Long-term exposure increases childhood respiratory tract infections and affects fetal development; increasing the risk of low birth weight and preterm birth. “These are predictive of a large range of later diseases.” 

“There is also growing evidence of an increase in the risk of asthma and cardiovascular disease. The newest observations indicate that the risk of diabetes and Alzheimer's will grow. Additionally, animal test models support the carcinogenic effects of air pollution. The strongest evidence we have is on the risk of lung cancer.”

The impacts of both long and short-term exposure are evident even in Finland’s statistics though we are considered a clean country. “The Espoo Cohort Study has monitored people born between 1984 and 1989 up to this day. The study has accumulated evidence that exposure in the 80s and 90s has increased the risk of developmental disorders in fetuses and later risk of asthma.

The concentration standards for air pollutants are exceeded continuously in Europe,” Jaakkola says. “There is evidence of hazardous effects resulting even from concentrations lower than the set standards. According to the World Health Organization (WHO), air pollution from population centres form the most significant hazard for the environment.”

In the future, CERH intends to research the joint effects of genes and air pollution. Results on asthma will be available soon. At the moment, we know that cigarette smoke and a mutation in a certain gene have a cumulative effect on adult asthma. “This is also interesting with regard to air pollution, as cigarette smoke contains many of the same substances as urban air pollution.


Societal impacts of climate change also pose a hazard to health

The most peculiar of the secondary health impacts that result from climate change may come about with the melting of the permafrost: there is a risk that pathogens such as the potato blight bacteria (Phytophthora infestans), which have been preserved in the permafrost, will be released. Cases such as this of Phytophthora infestans in deer have already been reported in Russia, but Jaakkola regards this information with some caution.

The third group of health impacts resulting from climate change manifest through social structures and changes such as migration. CERH is also aiming to focus on this area of research.

“One of our research projects aims to study the holistic effects of climate change on the Saami culture and the health and well-being of the Saami people. Traditional Saami culture is in close interaction with nature, and climate and environmental change are the swiftest in the areas populated by the Saami people. Impacts are caused by a diverse range of issues: livelihoods, faith in the future, language...”

The three-year project has not yet come to an end, but the professor is familiar with a dark precedent. “Innuits experience episodic suicide epidemics, because climate change has altered their traditional way of life and environment so much that young men no longer see a place for themselves in the world.”


Text: Jarno Mällinen



Last updated: 16.11.2018