Under a clear blue sky, you watch a little boy laughing as he runs alongside a butterfly in the park. A young girl races across a soccer field to score a goal. They stop to catch their breath. A sparrow flies by. Your thoughts probably don’t wander to the history of clean air in the US – or whether that bird needs a bath.
But they are connected.
We know that, generally speaking, children in the US today are breathing visibly cleaner air than children of generations ago – especially when it comes to soot, i.e., black carbon, from coal-burning plants and industries. But as the administration rolls back or nullifies a host of environmental regulations, aimed to protect the health of our families, it’s important to understand just how far we’ve come in the fight for clean air – and to realize what we stand to lose.
So how do we measure how far we’ve come?
Well, in regard to soot, suppose we could measure and compare sample accumulations of the actual soot in the air that people were breathing during past eras in US history? Where could we find scientifically measurable, accurately dated accumulations of soot that could be compared?
Shane DuBay and Carl Fuldner, graduate students at the University of Chicago, came up with an innovative answer: museum ornithology collections.
Dirty Birds Tell the Tale
They measured the amount of soot accumulated in the plumage of more than one thousand bird specimens, spanning 135 years, in the collections of three natural history museums, in Chicago, Pittsburgh, and Ann Arbor.
Because each bird corpse had been meticulously tagged with the date and location of its demise, and since the birds would have molted their feathers each year, the amount of soot on each bird was that which had accumulated in the year of its death.
When DuBay and Fuldner plotted a graph of their measurements for the years 1880 through 2015, it read like a history of coal-burning air pollution in cities of the Midwest industrial belt.
They found that the dirtiness of the birds peaked during the first decade of the 20th century, at the height of industrialization. During the Great Depression, bird specimens were much less dirty, reflecting a drop in coal burning due to economic constraints. In the years approaching World War 2, dirtiness increased as factories revved up again for wartime production.
Individual cities had at times attempted to do something about soot-blackened skies. In 1939, after a “Black Tuesday” in which street lamps had to be lit during daylight hours, St. Louis passed a “smoke ordinance” that resulted in some improvement in air quality. Chicago and Philadelphia also made attempts in the forties. But local regulations couldn’t solve a far-reaching problem. After all, the air we breathe doesn’t recognize where the city line begins and ends.
Less Dirty Birds
The birds were much cleaner in the 1950s and 60s, the era in which air pollution became recognized as a growing national problem. The federal government began addressing it, supporting research into, and mitigation of, air pollution, starting with the Air Pollution Control Act of 1955. The Clean Air Act followed in 1963, and the EPA was created in 1970. The birds were cleaner from then on – visible, date-verified proof that legislation and regulation work.
While the study was limited to soot levels, it has implications for current and future threats from both air pollutants and this administration.
“The fact that the more recent birds are cleaner doesn’t mean we’re in the clear,” DuBay notes. “While the US releases far less black carbon into the atmosphere than we used to, we continue to pump less-conspicuous pollutants into our atmosphere —those pollutants just aren’t as visible as soot. Plus, many people around the world still experience soot-choked air in their cities.”
Keep Up the Fight
“What we know, when we dig into the rich environmental history of the cities in the manufacturing belt is that the initial push against urban smoke, against urban air pollution, started at the city level…with citizens’ groups, reform groups. And they were often led by women — women’s groups that were combating the smoke issue.”
Bird specimens track 135 years of atmospheric black carbon and environmental policy DuBay and Fuldner, Proceedings of the National Academy of Sciences