Why We’ll Need More Than Just Inhalers if Climate Change and Air Pollution Persist

We’re all familiar with the saying, “you are what you eat,” but when it comes to respiratory health, you are what you breathe. With increasing air pollution, what we are breathing is becoming an increasingly relevant question to public health. The answer is multidimensional, involving not only the chemical substances being emitted into the air, but also the size of those particles. In their paper, “Climate change, extreme weather events, air pollution and respiratory health in Europe,” authors De Sario, Katsouyanni, and Michelozzi analyze a third dimension: the interaction between air pollution and regional weather patterns. The authors conduct a systematic analysis of epidemiological studies coupled with regional environmental information to identify the effects of air pollution and climate change hazards on respiratory health. Their analysis reveals a synergistic effect between climate change and the effects of air pollution on respiratory diseases, primarily through the increased frequencies of heat waves, the occurrence of Sahara dust storm events, and the larger dispersion areas for air pollutants and allergens.

The study uses data points on local weather patterns from over 50 European cities spanning the period from 1990 to 2004. The authors then overlay the regional weather events with results from independent epidemiological studies conducted in Europe to analyze the relationship between air pollution and respiratory disease. Taken together, the authors tease out the relationship between climate events, concentrations of air pollutants and allergens, and their combined observed effects on respiratory health.

In their large multicity study of short-term effects of extreme temperatures on respiratory health in Europe, the authors find an interaction between air pollution, heat waves, and their overall effects on respiratory health. For example, London, with higher ozone levels, shows significant increases in respiratory mortality during extreme heat periods. This can be contrasted with Athens, with a different air pollutant profile, where there was no significant increase in respiratory mortality, but instead an increase in respiratory related hospital admissions during extreme heat periods. Overall, the cities in this study show a positive association between extreme temperatures, the presence of air pollutants measuring 10 micrometers or less in diameter, and increases in respiratory mortalities or hospital admissions for specific respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and pneumonia. The observed effects were greatest in high-risk groups, specifically among young children and the elderly.

The authors next analyze the relationship between dust storms and respiratory health. Europe is affected by dust storms originating in the northern Sahara in Africa, where regional weather patterns transport these particles primarily to Mediterranean countries. The authors study the effects of fine and coarse particles from large Sahara dust storm events on respiratory mortality and respiratory related hospital admissions for seven cities throughout Europe. The results were less conclusive, with different cities showing varying effects during dust periods. The authors conclude that the differences are due to other unmeasured variables such as humidity levels, local temperatures, and effects on different subgroups.

While the study does not provide conclusive evidence that regional climate change patterns exacerbate the effects of air pollution on respiratory health, the authors do show that a synergistic relationship exists and that further research is needed to fill in the information gaps needed to craft effective pollution and air quality policies. Future studies may look at other variables affecting the presence and persistence of air pollutants, such as humidity and precipitation, as well as specific effects on population subgroups.

Although the study focuses on Europe, the results can be applied to the US, given comparable levels of urbanization and air pollution. More broadly, these results can be applied to developing countries, since the primary air pollutants of concern arise from the chemical processes used in vehicles and industrial manufacturing. Regardless of location, the authors’ paper demonstrates need for additional research collaboration among policy makers, scientists, and public health professionals to create solutions to this complex global problem.

Feature Photo: cc/(Manuel Boo)