Rising Global Temperatures Can Have Adverse Impact on Air Quality

According to a recent journal article on air quality across the Mid-Atlantic region, rising temperatures caused by climate change will considerably shift climatic conditions. This, in turn, will lead to worse air quality by raising the number of days with high ozone concentrations.

The study was carried out by scientists at the University of Delaware’s College of Earth, Ocean, and Environment (CEOE).

Cristina Archer headed the CEOE team as the members collated almost five decades’ worth of data from the Delaware Department of Natural Resources and Environmental Control (DNREC) climate and air monitoring models to examine the climatic trends. The researchers found that increasing temperatures will raise the number of days in a year where the concentrations of ozone in the planet’s lower atmosphere become hazardous.

According to Archer, DNREC is mainly concerned with near-ground ozone levels for two major reasons—compliance with state and federal regulations limiting high concentrations of ozone, and impacts on human health. Archer’s study was funded by DNREC.

Ozone has large negative impacts on health, especially affecting the cardiopulmonary and respiratory systems. It is especially bad if you already have a respiratory condition, asthma, for example, or an infection. In Delaware, we are barely in attainment or slightly in non-attainment (of ozone regulations). When we are not in attainment, the Environmental Protection Agency has to act. That is the relevance. That is why we need to know now there is a problem, so we can act on it.

Cristina Archer, Professor, College of Earth, Ocean, and Environment, University of Delaware

The Journal of Applied Meteorology and Climatology recently featured the study, titled “Global Warming Will Aggravate Ozone Pollution in the U.S. Mid-Atlantic.”

A professor in CEOE, Archer has a joint appointment between the Physical Ocean Science and Engineering (POSE) program of the School of Marine Science and Policy and the Department of Geography.

Joseph Brodie, a former graduate student and postdoctoral researcher at CEOE, and Sara Rauscher, an associate professor in the Department of Geography, contributed to the study and writing. Brodie is now the director of atmospheric research at the Rutgers University Center for Ocean Observing Leadership.

Ozone existing in the Earth’s upper atmosphere helps in blocking dangerous ultraviolet (UV) rays from the sun. Conversely, ozone nearer to the Earth’s surface—the target of the research—can cause pulmonary complications among the population.

Aggravation of chronic lung diseases, coughing, inflammation of lung cells, exacerbation of asthma, and irritation of the chest and throat are also associated with near-ground ozone. The immune system has disease-fighting capabilities, which are also reduced by ozone.

On days where the concentrations of ozone levels are sufficiently high, extended exposure can even cause permanent damage to the lungs. The EPA regulates ozone as a pollutant because of its hazardous nature.

Photochemical reactions between volatile organic compounds (VOCs) and nitrogen oxides (NO_x) result in the formation of near-ground ozone. The sun’s strong UV rays serve as a catalyst for the reactions occurring between the VOCs and NO_x emissions.

NO_x emissions take place when fossil fuels like gasoline and coal are burned by power plants or cars. VOCs occur from a range of sources, such as gasoline-burning engines and cars, chemical manufacturing, industrial solvents¸ cleaners, insecticides, and paints. They are also man-made.

Archer also informed that ozone is a secondary pollutant and hence it is difficult to limit the concentrations of this gas.

There are primary pollutants that are emitted and there are secondary pollutants that form in the air. Ozone is one of these [secondary pollutants]. You can’t go to a smokestack and measure the ozone coming out. You’ll get precursors or other compounds that form it but never ozone itself.

Cristina Archer, Professor, College of Earth, Ocean, and Environment, University of Delaware

Near-ground ozone is not a major problem for Delaware most of the time. As described in Archer’s paper, in Delaware, the average number of high-ozone days during the 1980s was around 75, while by 2015, it was below 20, reducing by roughly two days every year owing to more rigorous air quality regulations.

Conversely, the research team observed that rising temperatures caused by climate change are threatening to reverse the reduction in near-ground ozone pollution and raise the number of days where the concentrations of surface ozone become hazardous.

Conditions leading to high-ozone days are characteristic of hot summer days.

As global temperatures rise, summers will continue to become hotter and will result in more days with high concentrations of ozone. In addition, more high-ozone days can occur during the spring and fall seasons, because rising global temperatures will make those seasons warmer on average, Archer stated.

Global temperatures have increased by 1 °C as of 2019, according to the Intergovernmental Panel for Climate Change. By the end of the 21^st century, this will rise by another 1 °C. Archer also stated that high-ozone days themselves are likely to become stronger because of increased ozone levels.

The rise in the intensity and number of high-ozone days is a major concern because the adverse health impacts affect anyone who spends plenty of time outdoors, including people and children who go out to exercise or play. During the summer, an increasing number of people go outside more frequently and this would possibly increase human exposure to hazardous near-ground ozone levels.

In the article, Archer stated that a “business as usual” strategy will certainly lead to a dangerous increase in high-ozone days. The country requires more rigorous regulations if it is planning to restrict the number of high-ozone days, she concluded.