We talked to EXHAUSTION researcher Ulas Im from Aarhus University and EXHAUSTION coordinator Kristin Aunan from CICERO about the links between air pollution and climate change.
“In a warming climate, the concentration of air pollutants, such as ozone and secondary particulate matter, are expected to increase. In addition, we are expecting increased risks of wildfires due to global warming, which again contribute to more air pollutants”, explains Ulas Im, Senior Researcher at the Department of Environmental Science at Aarhus University.
New WHO Air Quality guidelines increasingly recognize the health damage from air pollution
On September 22 the World Health Organization (WHO) presented the updated WHO Global Air Quality Guidelines that recommends new air quality guidelines for key air pollutants. In addition to leading to adverse impacts on human health, some of these pollutants also contribute to climate change.
If the new guidelines are reached in all parts of the world, five to six million premature deaths - or 80% of the global mortality burden from air pollution - can be avoided, Dr Michał Krzyzanowski, Co-Chair of the Guideline Development Group, said at the online launch.
“The updated guidelines increasingly recognize the health damage from air pollution, even at lower concentrations than previously thought. However, considering current global warming, it will be even more difficult for large parts of the world to stay below the recommended levels unless much more ambitious mitigation efforts are put in place”, explains Kristin Aunan, Research Director at CICERO Center for International Climate Research and coordinator of the EXHAUSTION project. Aunan is also a member of the Scientific Advisory Panel of the Climate & Clean Air Coalition.
“Decisions at the upcoming UN climate change conference will be very important for air pollution and people’s health” Aunan says.
Climate change and air pollution
Climate change may amplify the health impacts of air pollution.
Illustration by InfoDesignLab in collaboration with researchers in the EXHAUSTION project.
In the EXHAUSTION project, Im is leading the work on climate projections studying how climate change together with air pollution will evolve in the future. The project aims to find out more about how this will impact human health in Europe. There are many uncertainties, but when the climate is changing, that also affects air pollution. Im and colleagues in the EXHAUSTION project are working to find out more about this interaction, looking at scenarios with different level of mitigation efforts.
“Further on in the project, we might be able to say more about whether Europe will be able to reach the air quality thresholds recommended by the WHO”, says Im, underlining that the uncertainty in the projections is quite large.
“In any case, reduction in man-made emissions from traffic, industry and energy production and use will have a positive effect both on health impacts and climate impacts”, says Im.
Ulas Im, Aarhus University
Reducing methane will also have positive effects on air pollution
The recent IPCC 6th Assessment Report states that in addition to reaching net zero CO2 emissions, limiting other greenhouse gases, especially methane, could have benefits both for health and the climate. Methane emissions must be reduced – together with other greenhouse gases - in order to reach the targets in the Paris Agreement.
Aunan explains the link between the reduction of methane emissions and air pollution.
“With reduction in methane, air pollution from ozone will also go down. In addition to the positive effect this will have on the climate, as ozone is a short-lived but powerful greenhouse gas, it will also benefit health and contribute to reduced crop loss”, says Aunan. She points to the recent methane pledge led by the EU and the US and says this could be important both for reaching the Paris Agreement and in relation to the new WHO Global Air Quality guidelines, which introduces a new guideline for peak seasonal ozone levels. The pledge commits countries to collectively reduce emissions of methane from all sectors by 30% below 2020 levels by 2030 and to take comprehensive domestic action to achieve this target.
Kristin Aunan, CICERO
Air pollution and heat stress
According to WHO, exposure to air pollution is estimated to cause seven million premature deaths every year.
“Previous studies have shown that people are more sensitive to air pollution if they are also exposed to heat stress (synergistic effects). Thus, not only can global warming lead to a deterioration of air quality in itself, but the impacts of hotter temperatures can also worsen the health effects of air pollution through physiological and behavioral mechanisms. In the EXHAUSTION project we aim to quantify the amplifying effects using European health data”, explains Aunan.
Follow the project at exhaustion.eu and @EXHAUSTIONH2020
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