Climate change spiking ground-ozone levels, could lead to higher heart attack and stroke risk

Our battle in valiantly patching up the ozone layer is well-documented, and still remains an excellent example of the wonders we could accomplish if all the countries just got along. However, while ozone might serve us as a silent protector from 15 kilometres high in the sky, did you know that closer to the ground, ozone pollution is also a major driver of many human diseases?

Ground-level ozone is one of the byproducts released when UV radiation burns through nitrogen dioxide, the "happy-fun" molecules released when fossil fuels burn. Ozone, along with the other brown haze-y photochemical smog we see in metro cities, really puts humans through the wringer. We’ve seen it linked to decreased vision and shortness of breath. Now, it might be time to add cardiovascular diseases such as strokes and heart attacks to the list.

An extensive study assessing hospitalisation increase as a response to increased ozone levels found shocking results. According to its results, exceeding World Health Organisation’s (WHO) 100 µg/m3 safe-limit for ozone concentrations substantially hikes hospital admissions for heart attack, heart failure and stroke. In fact, the same is observed even for concentrations much lesser than the WHO limit.

The study covered databases spanning 258 million people in 70 cities across China, where the average daily eight-hour maximum ozone concentration hovered around 79.2 µg/m3. The researchers found that each 10 µg/m3 surge in the two-day average eight-hour maximum ozone concentration was associated with a 0.4% increase in hospital stroke admission and a 0.75% rise in heart attacks.

While these figures might look negligible, they are anything but. On hot summer days, ozone levels surge over 200 µg/m3, meaning 8% more people are hospitalised for a stroke and 15% more for heart attacks. And these numbers are from the contribution of ozone concentration increase alone, unaided by other air pollutants!

Climate change making matters worse

Furthermore, the quintessentially-meddling climate change is also fueling the fire, as usual.

"It is believed that climate change, by creating atmospheric conditions favouring ozone formation, will continue to raise concentrations in many parts of the world," notes Shaowei Wu, a study author.

Since ozone and the other pollutants in photochemical smog are primarily produced by motor vehicles, power plants, industrial boilers, refineries, chemical plants and other facilities that burn fossil fuels, switching to greener alternatives cannot be stressed enough. Ozone pollution is poised to become one of the primary risk factors in the future due to global warming, projections for Europe have shown.

"Our results indicate that older people are particularly vulnerable to the adverse cardiovascular effects of ozone, meaning that worsening ozone pollution with climate change and the rapid ageing of the global population may produce even greater risks of cardiovascular disease in the future," Wu goes on to note.

"The strong link between climate change and air quality means that reducing emissions in the long term to tackle global warming will play a key role in alleviating ozone pollution and improving the air that we breathe," a concluding editorial note from the paper stresses.

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