Despite clear skies, is the air dangerous? German reports indicate that around 40% of the world is exposed to high concentrations of ozone.

Despite clear skies, is the air dangerous? German reports indicate that around 40% of the world is exposed to high concentrations of ozone.

A holiday with clear blue skies. With no worries about rain, you feel like walking outside or getting some exercise. However, the "pleasantness" and the safety of the air you breathe do not always align.

Strong sunlight and heat are conditions that can lead to high ozone levels near the ground. When considering extreme heat, alongside heatstroke, we should also be aware of this less visible air pollution.

An article on the German news site Fehmarn24 reported, based on the EU's Earth observation program "Copernicus," that about 40% of the world's population was exposed to extremely high ozone levels near the ground in 2026. It also mentioned that wildfire smoke and dust are contributing to the deterioration of air quality worldwide.

However, it's important to be cautious in interpreting these numbers. According to the article, the analysis of ozone and Sahara dust was only up to September 15, and it is not a definitive annual assessment for 2026. Additionally, the corresponding primary source from CAMS could not be identified in this review. This article introduces "about 40%" as the figure reported by the original article, without independently supplementing the concentration thresholds or exposure times.


"About 40%" does not mean that about 40% of people fell ill

In news about air pollution, different issues such as "exceeding standards," "exposure to high concentrations," and "health damage" are often received as a continuous narrative.

However, the percentage of people exposed to a certain concentration and the percentage of people who show symptoms are not the same. To consider health impacts, it's also important to know the concentration level, how long it lasts, and what activities were done during that time.

The original article also reported that about 60% in Asia were exposed to extremely high ozone levels at least temporarily. On the other hand, about 17% mentioned for Europe falls under the category of "high or extremely high." Due to differences in regions and classifications, it cannot be simply read as a ranking with the same yardstick.

Large numbers can serve as an entry point to the issue. However, verifying what those numbers count is crucial for fostering appropriate awareness.


Ozone that protects the sky and ozone at breathing height

Many people might think of the "ozone layer" that protects the Earth from ultraviolet rays when they hear about ozone. While that is also ozone, its meaning changes depending on where it exists. In the stratosphere, it plays a protective role, but near the ground where we breathe, it becomes a harmful air pollutant.

Ground-level ozone is not directly emitted in large quantities from car exhausts or factory chimneys. It is a "secondary pollutant" created through chemical reactions under sunlight involving nitrogen oxides and volatile organic compounds.

In other words, looking only at the emission sources does not reveal the risk of ozone. The U.S. Environmental Protection Agency (EPA) explains that ozone can be transported long distances by wind and can reach high concentrations even in rural areas. Simply being away from busy roads does not guarantee safety.


Do not lump together smoke, dust, and ozone

Another issue highlighted by the original article is the smoke from wildfires and dust. The article introduces situations where wildfire smoke travels far from its origin and Sahara dust flows into Europe.

It's important to note that the term "bad air" includes substances with different properties.

Ozone is a gas, while the issues of smoke and dust involve airborne particles. PM2.5 is an indicator concerning fine particles, so its figures alone do not reveal the state of ozone. In addition to the color of the sky and visibility, it's necessary to see what pollutants are being measured.

Regarding wildfires, the size of the burned area and how much people are exposed to smoke are separate issues. Without considering the location of the fire, the surrounding population, and the direction of smoke flow, the impact on daily life cannot be grasped. Attention needs to be paid to areas not shown in footage of flames.


What appears on social media is the dilemma of "what to do about travel or exercise"

There was no confirmation of social media reactions to the Fehmarn24 article itself. However, existing public posts about ozone pollution reveal voices of uncertainty between daily plans and air quality. The following are summaries of related posts, not direct reactions to this report.

 

In the air quality community on Reddit, a poster planning a long-distance run in Pennsylvania expressed concern about the ozone forecast ahead of a beach trip to New Jersey. Even for trips meant to be enjoyed outdoors, there is an underlying anxiety about having to consider how to spend the day depending on the air quality.

In another post, someone who thought suburban air was fine based on PM2.5 figures felt the need to also investigate ozone, searching for maps and measurement methods. Although the poster mentioned their health condition, the cause of symptoms cannot be determined as ozone based on the post alone.

These are personal experiences and consultations, not surveys representing overall public opinion. Nonetheless, it can be understood that information directly related to daily life, such as "whether it's okay to go out today" or "how to change exercise plans," is needed beyond just "whether there is pollution."


In Japan, information about "photochemical smog" is a familiar clue

In Japan, ozone is not a distant issue. "Photochemical oxidants" related to photochemical smog include ozone. The warnings broadcasted in schools are connected to this issue.

The Tokyo Metropolitan Government explains that photochemical smog is likely to occur on days with strong sunlight, high temperatures, and weak winds. When warnings are issued, people are advised to avoid going outside and to stop outdoor activities and move indoors.

The EPA also suggests reducing time spent outdoors and the intensity and duration of exercise during times of poor air quality as a way to reduce ozone exposure. In many regions, concentrations tend to be higher from afternoon to evening, but there are regional differences. It's important to check local information rather than relying solely on time of day.

Particular attention should be paid by those with respiratory diseases like asthma, children, the elderly, and people who work outdoors. If symptoms like coughing or shortness of breath occur, it's necessary to stop pushing oneself and consult a medical institution according to the symptoms.

Just as you check the temperature and chance of rain in weather forecasts, it's also helpful to check local photochemical smog information. For school club activities or outdoor events, decisions to change activities should not be left entirely to individual participants. Such systems are useful.


"99%" and "4.2 million" are not figures solely related to ozone

The original article also mentions the overall health burden of air pollution. According to WHO's published data, in 2019, 99% of the global population lived in areas that did not meet air quality guidelines. Additionally, early deaths due to outdoor air pollution were estimated at about 4.2 million in the same year.

These should not be reinterpreted as "damages solely due to ozone in 2026." The target year and the pollutants addressed are different. WHO's estimate of 4.2 million indicates the burden of cardiovascular, respiratory diseases, and cancer associated with exposure to fine particles.

When reporting on air pollution, it's essential not only to present strong figures but also to explain what those figures pertain to.


Add air quality checks to "going outside when it's sunny"

What individuals can do is check information and change their actions as needed. However, individuals cannot take on tasks such as reducing emission sources or setting up monitoring networks.

Measures in transportation, power generation, industry, and systems that utilize daily warnings in life. Only with both can efforts to protect air quality reach everyday life.

This report also raises the question of whether it's okay to judge heat solely by temperature. Just because it's not raining and the sky is bright doesn't mean it's safe to spend time outdoors.

How is today's air quality? When planning for a sunny day, let's start by adding that check.


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