Ozone (O3) has a rather mixed reputation. High up in the stratosphere it protects us from too much radiation from the sun, but down on earth in our respiratory environment it causes and amplifies respiratory difficulties. Hence, it is very important to differentiate the 2 different layers and differential effects of concentrations of ozone in the air. A forthcoming study in the Lancet Regional Health Europe (Nov. 2023) by Tianyu Zhao et al. demonstrates the long-term, negative effect of higher concentrations of Ozone on lung function. The prospective cohort study followed individuals in multiple states and locations over 20 years and corrects estimated effects for other environmental effects (fine particles PM 2.5 pollution) and green environment. Faster decline in spirometric lung function is highly likely to be caused by higher ambient ozone concentrations. The study is based on 3000+ observations from 17 centres in 8 countries in Europe. Older persons in the range from 35 to 55 had a steeper decline in ozone-related decline in lung functions.
This is rather bad news for older persons living in inner cities where both ozone concentrations, mainly in summer, heat and micro-particles cumulate. Similarly, areas with frequent so-called inversion micro-climate, (a layer of cold air on top of SMOG blocks the renewal of air for extended periods) face particular health risks. Professions that work long durations outside in the sun or the exercise of sports during high ozone day-time run higher risks for a deterioration of their lung functions in the long-run. The medical evidence is there now, also for Europe, what had been shown already for the US before.
It is time to adapt our lifestyle to these health risks. High effort physical work outside should start as early as possible in the morning hours or even before sun rise. Staying indoors is highly recommendable for older persons and persons with reduced lung functions (asthma risks) during such periods of high ozone concentrations. Like it or not, even wearing a mask outside, when it is sunny and hot would be preferential, but is rather inconvenient. We need to shift airing living rooms or offices without climatization to early morning hours rather than ambient temperatures in the afternoon, when ozone peaks are prevalent.
These effects and remedies have been known for some time, but the evidence is much more compelling now (Zhao et al. 2023). Climate change in form of global and local warming, particularly in inner cities, will only exacerbate these effects in the coming years. Prevention measures need to be considered in public health measures as well as urban planning. We can do it, if we want to. Start now to benefit from the effects a decade later or for the benefit of younger generations. (Image: Int. Encycl. of public health, p.702). 
