Ozone: The Good and the Bad

Ozone, one of the six major pollutants addressed by the EPA in the Clean Air Act (CAA), is one of the most notorious air pollutants that became an issue with the rise of the industrial revolution. Ground-level ozone harms both human and environmental health, such as reduced lung function in humans and hindered growing capabilities in plants. Additionally, ozone is responsible for smog that cripples cities in China today, and was once common in Los Angeles and London. Under the CAA, the levels of ozone are regulated by the National Ambient Air Quality Standards (NAAQS), keeping ozone at a safe level for both humans and the environment.

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  Smog in Shanghai, China makes skyscrapers barely visible

Smog in Shanghai, China makes skyscrapers barely visible

Ozone is also addressed by the EPA in the form of the Montreal Protocol, an international treaty signed by 197 nations in 1987 to repair the hole in the ozone layer. The EPA has been acting as the authoritative body in the United States, enforcing regulations to curb unnecessary ozone-depleting substances which protect Americans and people worldwide from skin cancer and eye cataracts.

Wait a minute, how is the EPA reducing ozone and repairing the ozone layer at the same time? Why would the world want to repair the ozone layer? What is the ozone layer anyway?

The role of ozone in our atmosphere is unique and a little confusing. To answer the questions asked above, we need to understand a little bit about the Earth’s atmosphere, specifically the layers of the atmosphere. The lowest layer is called the troposphere, which is where all living things reside. The layer directly above the troposphere is the stratosphere, which is where the ozone layer is found. This concept is easier to understand when it’s visualized, like in Figure 1.

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   Figure 1 : Layers of the Atmosphere

Figure 1: Layers of the Atmosphere

To provide some context to Figure 1, the planetary boundary layer, where most living things are found, is about 1 kilometer (0.6 miles) above the surface. Though, in the context of this blog, the most important component of this figure is the temperature profile. In the troposphere, it gets colder as altitude increases, which isn’t news to anybody. What is interesting though is that about 20 kilometers (12 miles) up, in the stratosphere, the temperature begins to increase with increasing altitude. This is due to the ozone layer, which is shown in Figure 1 as the “Ozone Maximum” at approximately 20-30 kilometers (12-20 miles) in altitude.

            The ozone layer is the boundary where the atmosphere begins to warm because the high concentration of ozone absorbs large amounts of solar radiation, specifically ultraviolet (UV) radiation. UV radiation is what we protect ourselves from when we apply sunscreen at the beach, reducing our chances of getting a sunburn, or even skin cancer, among other things. Stratospheric ozone is essentially a natural sunscreen for Earth’s surface. This protective layer was damaged by the use of chlorofluorocarbons (CFCs) in refrigerants and aerosol cans over time until the Montreal Protocol was agreed upon virtually worldwide. Since it was enacted in 1989, the ozone hole has slowly recovered while alternatives to CFCs have been incorporated globally.

            Ozone is clearly beneficial to life on Earth, but that’s only true when it’s concentrated in the stratosphere. Tropospheric ozone, or ground-level ozone, harms humans and the environment, is a key ingredient in smog, and is a greenhouse gas. The harmful effects of ozone, particularly as a lung and eye irritant, are also a consequence of smog. Smog was a serious issue in the 1950s when there were little to no environmental regulations. The breaking point came in London in 1952 when thousands of people died over the course of a few days due to heavy smog that basically made breathing outside a death sentence and reduced visibility to near zero. Over the past 60 years, governments of developed countries have more or less eliminated the occurrence of smog. For example, since 1980, the US has decreased its ozone air concentrations by 32%, effectively reducing a necessary component of smog.

            It’s important to understand the dangerous effects of tropospheric ozone and the benefits of stratospheric ozone in the continued challenge of ensuring the health of our planet for ourselves and future generations. Despite the productive efforts of the EPA and the world, issues involving ozone are ongoing, and they will require the continued undertaking by all leaders and citizens of the world for the betterment of public health and well-being.

 

Jake Greif

 

Sources:

https://www.epa.gov/ozone-pollution/ozone-basics

https://www.epa.gov/air-trends/ozone-trends#oznat

http://geogrify.net/GEO1/Images/FOPG/0314.jpg

Air Pollution Fundamentals, notes from class

Photo sources:

https://pixabay.com/en/asia-china-shanghai-smog-77859/

Jake Greif

Jake Greif is a senior at Tulane University majoring in Environmental Earth Science, with a minor in International Development. As an Environmental Earth Science major set to receive his degree in May 2017, Mr. Greif has gained a good understanding of the systems that make Earth uniquely habitable, how our actions affect those systems, and how we can modify our actions to avoid harming the planet. A Dallas native, Mr. Greif has enjoyed his time in New Orleans and has held several internships to further his understanding of local environmental issues. Mr. Greif is excited to continue exploring his interests of hydrology and water management after receiving his degree.

Air Pollution is Everywhere

A search of “air pollution” on any major news website is bound to bring up recent articles about air pollution around the world.  I did this search on the New York Times website, and the first article to appear was “Protests in Iranian City Where ‘Everything Is Covered in Brown Dust’”.  The article talked about a city in Iran, Ahvaz, where the air quality is so bad that citizens are taking to the streets to protest the government, going so far as calling for the resignation of the local governor. Two articles later was about London’s air quality issues since diesel vehicles and wood-burning fires in private homes have become more popular. The quality of air is so bad, that it is being compared to the Great Smog that occurred in December 1952, with an estimated death toll of 12,000 people.

December 1952: London during the day during the Great Smog event (Soruce:  http://history1900s.about.com/od/1950s/qt/greatsmog.htm )

December 1952: London during the day during the Great Smog event (Soruce: http://history1900s.about.com/od/1950s/qt/greatsmog.htm)

Luckily, the frequency of these extreme events is falling, at least in the United States.  The Environmental Protection Agency (EPA) has been tracking major air pollutants since 1980, and the trend of almost all the pollutants the EPA tracks is that they are present in declining amounts.  One reason that the U.S. has less extreme air pollution events is that there is  legislation in place that helps to limit the amount of pollutants that are getting into the air.  An overview of federal regualtions can be found at http://www.dnrec.state.de.us/DNREC2000/Divisions/AWM/aqm/education/airqualityappx.pdf.

 

Unfortunately, the rest of the world has not had this same fortune.  A number of  cities, many in China and India, have become known for their low quality air, where people wear masks to avoid breathing in the air directly.  In May 2016, The World Health Organization (WHO) said that more than 80% of the world's population that live in urban areas are exposed to air quality levels that exceed WHO standards, by 5-10 times in some countries. Most of these people live in low- or middle-income countries, and are at increased risk for stroke, heart disease, lung cancer, and chronic and acute respiratory diseases, including asthma, due to regularly breathing low quality air.  Luckily, there is some good news.  In the past two years, the number of cities monitoring their air quality has doubled, and more cities are following the trend. Knowledge is power, and when cities take steps to monitor their levels, they may be able to reduce some types of pollution, and citizens benefit in the form of lessened disease risk and improved air quality.

 

 

Sources:

http://www.who.int/mediacentre/news/releases/2016/air-pollution-rising/en/

 

 

Hannah Leis

 

2/21/2017

Hannah Leis

Hannah Leis is a senior at Tulane University and will be graduating in May 2017 with a double major in Economics and Environmental Studies. During Fall 2015, Ms. Leis studied Sustainable Development in Copenhagen, Denmark.  While in the program, she developed a passion for sustainability based on the unique Copenhagen model.  Ms. Leis has held a number of environmentally-focused internships and jobs throughout the New Orleans area.  Ms. Leis has extensive experience working with Stata, disentangling federal environmental regulations, and researching various environmental issues. Ms. Leis is excited to launch her career in the environmental or sustainable development fields.  Her hobbies include SCUBA diving and exploring her adopted home of New Orleans.