Air pollution: highest impact emissions and Kawasaki disease

The effects of environmental pollution on human health are many: on the development of babies and children, on the increased risk of suffering a stroke, on mental health, etc. It is also the leading environmental cause of death. At the Barcelona Institute for Global Health (ISGlobal) they are working to learn more about the harmful effects of air pollution and thus be able to propose measures for a healthier world. Their two latest studies do just that.

Traffic, housing and agriculture in European cities

We refer to fine particles (PM_2.5) when we talk about those particulate materials present in the air that, due to their size, can enter the respiratory tract, making them a danger to human health. Among others, these are solid or liquid particles such as pollen, metals or combustion residues. As for nitrogen oxide (NO₂), it is a toxic gas that comes mainly from combustion processes. Both are air pollutants the levels of which in Europe are above those recommended by the WHO and which cause more than 100,000 premature deaths a year.

Now, a study led by ISGlobal has used public population, mortality and air quality data from 857 European cities to analyze which activities and sectors contribute most to mortality through these pollutants.

After processing the data and doing computational analysis, the research team found that PM_2.5 emissions from dwellings account for an average of about 50,000 deaths in the cities studied, while the agricultural sector, industry and transport are estimated to cause about 30,000 premature deaths each.

In terms of NO₂ levels, transport accounts for the highest mortality (about 50,000 estimated deaths), followed by industry, the energy sector and housing, with more than 10,000 premature deaths per year linked to each of them.

“If we look at NO₂ and PM_2.5 together, traffic continues to be the sector with the greatest weight in both poor air quality and mortality. But if we look only at mortality associated with PM_2,5 particles, we see a significant contribution from housing and the agricultural sector”            
Sasha Khomenko (ISGlobal)

If we focus on the Catalan province capitals, we find differences between the sectors whose emissions contribute the most to mortality. For example, in Tarragona the sector that represents the most mortality, both in NO₂ and PM_2.5 emissions, is industry. But the other three capitals follow the general pattern of the European cities studied, where we observe that transport is the sector that contributes most to mortality in terms of NO₂ and housing the one that contributes most in relation to PM_2.5. The data for these and the rest of the 857 European cities studied can be consulted in the ISGlobal Ranking.

It should also be noted that a study analyzing cities in smaller plots would give more accurate results, especially in smaller cities. Mark Nieuwenhuijsen, first author of the study states that “more courageous measures are required to drastically reduce pollution and deaths associated with traffic, which remains the main source of emissions. And, at the same time, implement policies to mitigate the other emission sources of both NO₂ and PM_2.5”.

Urban emissions, agriculture and Kawasaki disease

Kawasaki disease, which usually occurs in children, is characterized by a strong immune response against blood vessels following the entry of an unidentified agent into the upper respiratory tract. It usually manifests with the appearance of a rash and fever, but can get complicated and lead to the development of aneurysms or even sudden death. Although it is known that some environmental, biological or chemical factors can trigger it, research is still underway to determine the causes and agents that provoke it.

This disease shows seasonal patterns: during the northern hemisphere winter, cases on both sides of the North Pacific increase coinciding with the arrival of wind currents from Asia. Given this coincidence, a team led by ISGlobal has studied air pollution data from 20 locations in East Asia, and aerosol chemical composition data (metals and metalloids) from one prefecture in Japan for 37 days.

The results have shown that the days with the highest air pollution coincide with the highest incidence of the disease. It has also been observed that marine air inflows clean the atmosphere and when they arrive, cases of Kawasaki disease are reduced. In addition, “the analysis of the content of fine particles suspended in the air (aerosols), those that are more breathable and can penetrate more into the lungs, and their content in metals (with inflammatory capacity) can serve as an early warning system to prevent episodes of increased cases of Kawasaki disease”, explains Xavier Rodó, ISGlobal researcher and first author of the study.