Climate Change May Force More Unhealthy Ozone Days Every Year By 2050


The effects of climate change to ozone levels have been severely affecting people and the environment. By 2050, some parts of the United States are predicted to experience more unhealthy ozone days if air pollution and emission rates are not addressed, according to new research.

The study conducted by researchers from Harvard John A. Paulson School of Engineering and Applied Science (SEAS) suggests that some parts of the United States could encounter an additional of three to nine days of unhealthy ozone levels every year by 2050.

The study revealed that in some parts of the United States, particularly California and the Northeast and Southwest regions, will experience an increase in dangerous ozone levels up to nine days a year. Other U.S. regions could experience an average of an additional of 2.3 smoggy days per year.

Ozone is a gas molecule commonly known as smog, and develops from gases that come out of smoke-emitting sources such as tailpipes. The gases react and form ozone smog upon contact with sunlight.

"In the coming decades, global climate change will likely cause more heat waves during the summer, which in turn could cause a 70 to 100 percent increase in ozone episodes, depending on the region," said the study's first author Lu Shen, a SEAS graduate student.

Effects Of Unhealthy Ozone Days

The increase in unhealthy ozone levels will have a domino effect on health especially among those with respiratory illnesses. Dangerous ozone or smog could cause airway inflammation among children, elders and those people with weak immune systems, leading to asthma attacks.

Loretta Mickley, one of the authors of the study explained that high ozone levels can aggravate chronic lung diseases and may even cause increased mortality rates.

Temperature-Ozone Relationship

In the study, the researchers also looked at how the accelerated ozone levels are affected by temperature.

To be able to study the correlation of ozone levels and temperature, Mickley and Shen along with co-author Eric Gilleland of the National Center for Atmospheric Research, devised a model that used observed temperature-ozone relationships to predict ozone levels.

They explained that typically high temperature follows an increase in ozone levels but because of the stagnation of the atmosphere, the ozone or smog accumulates.

"The air just cooks and ozone levels can build up," said Mickley.

The domino effect of the temperature-ozone relationship in other regions in the United States however was not observed in places where there's an extreme temperature ranging from 32 degrees Celsius and above.

In areas with extremely high temperatures, the ozone levels may stop increasing, a phenomenon called ozone suppression. It was first observed in California.

The researchers tested whether ozone suppression is also present in other regions of United States. Surprisingly, they found out that 20 percent of the sites measured exhibit ozone suppression. This revelation in the study of predicting future ozone levels is more complex than what was thought earlier.

Shen said that the cause of the dropping off of ozone levels was actually meteorology, not chemistry. There's a tight correlation between temperature, ozone and meteorology, involving variables of solar radiation and circulation. However, these correlations break down at extreme temperatures.

"These results show that we need ambitious emissions controls to offset the potential of more than a week of additional days with unhealthy ozone levels," Mickley said.

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