Lentis/The Legacy of the Donora Smog of 1946

Introduction
First Established in 1901, Donora is a town in Pennsylvania approximately 20 miles south of Pittsburgh. Around that same time the first steel mill operated by the Union Steel Company was constructed. By the year 1948 this mill, as well as another constructed near it, would be owned by the American Steel and Wire Company. Having brought many jobs to the Donora area, the population of the town grew to approximately 14,000 by 1948. It was that same year in which an environmental disaster took place over Donora. Having lasted 5 days in October from the 26th - 31st, heavy amounts of air pollutants like carbon-monoxide and heavy metal particles resided above Donora. This event resulted in the deaths of 20 individuals and caused lasting health effects for many more. As a result of this incident, legislation such as the Air Pollution Control Act of 1955 and the Clean Air Act of 1963 were passed in order to prevent such a disaster from reoccurring in America.

Main Contributor
The bulk of the air pollution came from steel mills owned by American Steel and Wire Company. Originally the steel mill was constructed in 1900 and was acquired by American Steel from Carnegie Steel in 1908. With WWI starting in 1914, the demand for steel rods and wires grew dramatically. To help meet this demand a secondary mill, Donora Zinc Works, was constructed in 1915 by American Steel. The main purpose for this mill was to smelt zinc ingots which would be shipped to other steel mill to be used as a protective coating for steel products.

On October 29th, 1915, the first zinc ingot was smelted at Donora Zinc Works. The methods in which they smelted Zinc created several by-products such as cadmium, lead, and sulfuric-acid. Because of this, large amounts of heavy metal particles would be thrown into air and remain in the soil. Additionally, toxic gasses such as carbon-monoxide and sulfur-dioxide filled the air of the nearby town. During the smog disaster of 1948, its estimated that amount of sulfur-dioxide in the air reached as high as 5,500 μg/m3. This heavy pollution caused 17 of the 20 deaths within twelve hours, and resulted in several thousand other cases of respiratory problems.

Weather Effects and Contributing Factors
While the smog over Donora existed prior to October 26th, the disaster lasted for five days for specific reasons. On the date of October 26th a cold front moved in over Donora. With little to no wind and warmer air remaining stagnant above this cold front, an event called a Temperature Inversion took place. This trapped much of the pollution at a low altitude and was blocked in by the hills surrounding Donora. The combination of the inversion and the geography surrounding the town is what caused the disaster to last five days. With high amounts of smoke residing at nearly ground level, the visibility for first responders and other pedestrians was extremely poor. This made reaching citizens in need increasingly difficult towards the end of the event.

Donora's Reaction and Aftermath
As the mill grew so did the town, and by 1948 nearly half of Donora, 6,500 people, worked for American Steel at one of the mills. This made it hard to speak out against Donora Zinc Works as many residents depended on the mills financially. Additionally, six of the seven members of the Donora council were employed by American Steel, and they feared job losses if the mill was regulated. It wasn't until the 20th resident died that the mills halted production of steel and zinc ingots on Sunday, October 31st. Accusations were immediately directed at Zinc Works for the use of reprocessed materials in the furnaces. Eventually, Zinc Works would close in 1957 while still denying any responsibility for the incident. Ten years later all American Steel mills would close down in 1968.

Acute Health Effects
During the multi-day smog event, 20 people died from causes related to the smog and an estimated 5000-7000 were cited as became very ill. Data collected in the study after the event showed that 43% of the population of Donora's health had been effected in some way. The most common symptom resulting from the poor air quality was dyspnea or difficulty breathing. Some of the pollutants found in the smog of Donora that contributed to the negative health effects on the population are listed below. Other pollutants researchers found were present included carbon monoxide and nitrogen dioxide.

Long Term (Chronic) Effects
The acute health effects experienced by the residents of Donora were not the end of the harm stemming from the event. A decade after the smog event, the mortality rate of Donora was higher than it had been before 1948 as well as higher than that seen in nearby areas. Many affected by the smog additionally developed detrimental symptoms such as cancers and cardiovascular disease. The cumulative mortality rate adjusted for age from the year 1948 to 1957 split by gender can be seen in Figure 1. In the survey conducted to obtain these data an acute illness was recorded if a person was affected immediately following the smog of 1948. From this plot we can see that the group who were affected displayed a higher mortality rate in the following eight years compared to those who had not been affected by the smog.

Resulting Environmental Regulations
The Donora Smog was one of the most pivotal events leading to the adoption of air quality regulations in the United States. Prior to the event, clear skies were considered an indicator of economic depression, whereas cloudy skies were a sign of prosperity. Another contributing factor towards federal legislation on air pollution was the Great London Smog of 1952. From December 5th to 9th, a combination of industrial pollution from coal-burning furnaces and a temperature inversion resulted in a deadly smog that claimer over 4,000 lives.

Air Pollution Control Act
Continued concern over events such as the Donora Smog and the Great London Smog led to the creation of the Air Pollution Control Act of 1955, which was the first federal legislation involving air pollution in the United States. This Act allocated federal funds towards research on the scope and sources of air pollution, and served as a national warning about the dangers of air pollution.

Clean Air Act
The Clean Air Act of 1963 was swiftlfy passed by Congress and signed into law by President Lyndon B. Johnson. It was the first federal legislation for air pollution control which established a federal program for monitoring and controlling air pollution.

The historic Earth Day of 1970 and growing public concern over environmental pollution, culminated in Congress passing a more stringent Clean Air Act. The Clean Air Act of 1970 established federal and state regulations to limit emissions from industrial and mobile sources. This included the National Ambient Air Quality Standards (NAAQS), State Implementation Plans (SIPs), New Source Performance Standards (NSPS), and National Emission Standards for Hazardous Air Pollutants (NESHAPs). NAAQS set limits for six principal pollutants- carbon monoxide, lead, nitrogen dioxide, ozone, particulate soot levels, and sulfur dioxide. In the same year, the Environmental Protection Agency (EPA) was established to regulate and implement these limits to prevent another incident like the Donora Smog from occurring again. For example, the Act set a limit of 80 micrograms per cubic meter on the amount of sulfur dioxide allowed in the air, whereas there was around 1,500 to 5,000 micrograms of sulfur dioxide per cubic meter in the air during the Donora incident.

Conclusion
The Donora Smog of 1948 was an important event in paving the way for enacting environmental regulations to control pollution. While the event was extremely detrimental to the health of the residents of Donora, in the long run its legacy helped prevent other cities in the United States from experiencing similar effects from air pollution. In this chapter we explored the contributing factors to the smog and the town's reaction, the acute and chronic health effects caused by the high levels of air pollution seen, and the resulting environmental regulations.

Next steps would include looking at places around the world where smog events are still occurring. For example, China and India contain 90 percent of the 200 cities with the worst air pollution, and over 1 million premature deaths every year in China are due to air pollution. It is important that we remember the lessons learnt in Donora about the dangers of air pollution and the need for regulations to limit emissions of air pollutants.