The report “Interactive Effects of High Temperature and Air Pollution in Europe” summarizes the evidence from several analyses on the interactive effects of high temperature and various air pollutants on heart and lung related death and diseases across Europe. This is the most comprehensive and extensive analysis yet done on this question.

We have interviewed one of the authors of the report, Dr. Alexandra Schneider, at Helmholtz Munich.

Alexandra Schneider, Helmholtz Munich

Could you explain the most important findings related to this work?

“We knew from previous studies that there is an increased risk of heart and lung disease and death associated with heat exposure in the warm season. The current work now shows that the risk is enhanced when people are exposed to high levels of air pollution at the same time,” says Schneider.

The study was conducted at three different levels:

• At city-level across 15 countries in Europe

• In small areas (e.g. suburbian areas or municipalities) in Norway, England and Wales, Germany, Italy, and Greece and

• At individual level, through cohort data in four countries: Germany, Italy, Norway and Sweden.

Air pollution remains a health risk

The most harmful air pollutants were studied, particulate matter [PM2.5] and ozone [O3]. The source of these air pollutants can be e.g. fine particles: In industrial countries, millions of people live in urban areas with elevated levels of air pollution due to burning fossil fuels for energy and transportation in industrial processes or traffic.

“Although successful efforts for emission control have been undertaken in the developed world, there is existing epidemiological evidence that air pollution remains a health risk even under current regulations,” says Schneider.

Schneider explains that rapid expansion of industry, increased automobile and truck traffic and high demands for powering homes, especially in large urban areas, result in severe air pollution problems.

Ozone

Ozone is not released by a pollutant source, but is essentially created as a by-product of complex conversion processes.

­“Volatile organic compounds and above all nitrogen oxides from car exhaust gases are involved in these mechanisms. Solar radiation provides the energy for the formation of ground-level ozone. As a result, particularly large amounts of ozone are produced in summer and in anthropogenically polluted air masses,” says Schneider.

High levels of air pollution and high temperatures has an effect on heart and lung related death and disease

What happens when people are exposed to high temperatures and there are high levels of air pollutants at the same time?

“A clear interaction between high temperatures and particulate matter [PM2.5] was observed, with highest heat-related increases in deaths and increased rates of hospitalisation on days with high levels of PM2.5. On the days with lowest levels of air pollution from PM2.5, we also saw the lowest rate of heat-related hospitalisation and mortality.”

Schneider says they also found evidence of interaction between high temperatures and ozone for heart and respiratory death, with highest increase in mortality on days with a high level of ozone. They could not find a consistent interaction between high temperatures and ozone with regards to the occurrence of diseases.

The study was conducted in different countries with different weather conditions – what are the main differences between cold and warm areas?

“We observed large regional differences in the heat effects as well as for the interactive effects with air pollutants. A significantly higher heat effect with elevated concentrations of air pollutants was observed in countries like Portugal, Spain, the UK, Germany, and Switzerland. In contrast, results from other countries like Norway and Sweden followed inconsistent patterns.”

In the analysis of the small areas in Norway, England/Wales, Germany, Italy and Greece, a north-south gradient was found, with heat effects on total mortality being stronger in the south (Italy and Greece) and weaker in the north (Norway).

Urgency in planning measures to improve air quality across Europe

How do you think this study can inform policy making in Europe?

“The study can help stakeholders and policy makers to plan adaptation measures to protect the vulnerable and susceptible population subgroups; certain parts of the population are more prone to react to elevated temperatures and air pollution levels, and therefore need better protection than others,” says Schneider.

“The findings highlight the urgency in planning measures to improve air quality across Europe. If measures are implemented they could increase European resilience towards climate change.”

Here you can download and read the full report developed by researchers in the EXHAUSTION team.