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Real Science

Human impact on the environment

Michael Rosenthal

(11/2015) This month we’re going into more detail on the issue of human impact upon climate. There is absolutely no doubt in the scientific community that atmospheric pollutants have an impact on local weather and on climate. When I was growing up in northeastern Ohio, there was an event in a nearby Pennsylvania town in which poisonous smog hung over the city. The Donora Smog occurred in 1948, in Donora, PA, a town of 14,000 residents, 24 miles south of Pittsburgh. It was caused by chemical emissions form the United States Steel Donora Zinc Works due to a temperature inversion, a phenomenon caused by warmer air above trapping pollutants in cooler air below. Donora had a thick, yellowish, acrid smog that lasted five days. Caught in this inversion layer were sulfuric acid, nitrogen dioxide, and fluorine gas, among other poisonous chemicals. When it rained, 5 days after its start, and the smog dispersed, 20 residents and some 800 animals had died, and one-third to one-half of the population of 14,000 was sickened. Fifty more residents died in the following month from respiratory causes due to the event.

Researchers analyzing the event have focused on the pollution from the zinc plant, which had previously killed all vegetation within a half-mile radius of the plant. Fluorine (F2) gas was concluded to be the primary cause of the deaths. There are only 6,000 residents today in Donora. The Donora Smog Museum was opened in 2008 in the town, which has never recovered economically from the event.

So, let’s look at some of the most common atmospheric pollutants, where they come from, and what impact they have. As mentioned in an earlier column, carbon dioxide (CO2) is a result of burning any substance containing carbon (C), most of which we label as fossil fuel: coal, oil, natural gas, and others. If you have a fire with wood and brush in your yard, or burn charcoal in a barbecue grill, you’re releasing carbon dioxide. It is a colorless gas, not poisonous in its own right, unless it prevents you from access to oxygen, in which case it can smother you. There will always be emission of carbon dioxide, but it needs to be controlled, since through the previously mentioned greenhouse effect it leads to global warming. This is perhaps the most worrisome atmospheric "pollutant" we produce, and the one which sparks the greatest controversy.

Carbon Monoxide (CO) is a gas that results from incomplete combustion. It is extremely poisonous, and is the substance that kills you if you inhale too much automobile exhaust when the source of oxygen is restricted. Carbon Monoxide poisoning will result from inhaling car exhaust in a closed space, such as a garage, or from a faulty combustion device such as a bad furnace. Carbon monoxide is also a component in the production of ozone (O3).

Ozone has an important function. The ozone layer in the atmosphere shields people from harmful ultraviolet (UV) radiation. However, ground level ozone is poisonous, and results from other pollutants in the presence of the energy from sunlight. Ozone is a major component of smog, and can contribute to severe health problems, particularly asthma. There is a current controversy on ozone standards. The EPA wishes to reduce the allowable level of ozone in the atmosphere. The government maintains that this will improve public health. Others in Congress, in particular the 18 members of the House of Representatives Doctors Caucus, oppose the lowering of the standard, saying that there is not enough evidence to blame ozone as the culprit in asthma and other health problems, and that more study is needed before putting pressure on industry from a lower standard. More study is needed here.

Nitrogen oxides (N2O, NO, NO2) are primarily created by combustion in road transport. Nitrous oxide (N2O) is an important global warming contributor, nitrogen dioxide (NO2) is involved in ground-level ozone forming chemistry and is also a component of smog. None of these is good for the environment. N2O was once extensively used as a dental anesthetic, and is known as "laughing gas." It was very popular at one time among drug users!

The burning of fossil fuels to create electricity also coverts sulfur present in the fuels to sulfur dioxide (SO2). It contributes to smog, combines with rainwater to form acid rain, and causes breathing problems for those with asthma.

The agricultural use of fertilizer, natural (manure) and synthetic, releases ammonia (NH3) into the atmosphere. It can react with other pollutants to produce particulate matter, and it over-enriches ecosystems with nitrogen.

Volatile Organic Compounds (VOCs) occur naturally in the atmosphere from both vegetation and human activity. Some of these are toxic to human beings and animals, and they can contribute to smog and ozone levels. Methane (CH4) is a VOC that contributes to global warming. Sources include farm animals and rotting garbage,

And finally, particulate matter comes from a multitude of sources, causing atmospheric haze and lung problems.

So, in the course of this survey of atmospheric pollutants caused by human activity, I have managed to insert a chemistry lesson! Have I mentioned that I taught chemistry at the college level for 50 years or so? At any rate, I love atoms and molecules and, as you can see, I find any excuse I can to talk about them.

Human activity will always have an impact on the environment around us. We need to find ways to minimize the negative aspects of the activity for our own good, long term and short term. This is not easy. But if we wish to maintain a planet that is healthy and livable, we need to raise our consciousness on this issue and work harder at it.

The New York Times recently ran an editorial entitled "Teaching the Truth About Climate Change." The point they made is that misinformation about climate change is common. Polls have indicated that as many as 34 percent of people believe that scientists disagree on whether global warming is happening, when in fact an overwhelming majority of scientists believe that climate change is here and that human activity has caused it. A great deal of this problem, they point out (and I fully agree!), lies in our educational system.

Fifteen states and forty school districts in other states have adopted the Next Generation Science Standards, released in 2013, developed by a committee of scientists and education experts and refined by teams in 26 states. Some states have resisted, refusing to admit that change has occurred and continues to occur, while others have taken an energetic lead in educating students on this critically important topic. The Times editorial argues "children need to understand how climate changes came about, how to mitigate them, and how to prevent more damage to the planet." I couldn’t agree more strongly!

This is not an easy problem to analyze or to solve. Short-term effects may not be always blamed on global negligence. Some summers are hotter than other, some periods are rainier than others, but environmental pollution such as the Donora smog is not natural. We need to do everything we can to protect the earth in both the short run and for the long haul.

Are we alone in the universe? In spite of all the nonsense propagated on alien visitation, it is still hard to believe that in such a vast universe we are all alone. But there is no firm evidence yet, as we’ve previously discussed, that we’ve ever had an alien visit. Radio telescopes have been used since the 1960s to listen for evidence of extraterrestrial life, and the project called Search for Extraterrestrial Intelligence (SETI) has been funded by private donors since government funding was withdrawn in the early 1990s. The fund-raising effort was taken over by the non-profit SETI League. A recent pledge by the billionaire Russian Internet entrepreneur Yuri Milner of $100 million has given the project a boost. Studies have shown that there may be as many as 10 billion Earth-sizes planets at tolerable temperatures in the Milky Way alone! So even though we did not have an extraterrestrial visit at Roswell, New Mexico, we can’t count out the possibility that extraterrestrial life exists.

Michael is former chemistry professor at Mount. St. Marys

Read other articles by Michael Rosenthal