High School High School Biology and Chemistry TSS

Down to Earth with Fireworks

How much of these carcinogenic and hormone-disrupting substance-bearing fireballs do we need to seep into soil, water, and our lungs?

And the rocket’s red glare, the bombs bursting in air, gave proof through the night that the chemicals were still there…

So maybe you read about the science of fireworks and how they get their colors, but as a scientist, did you ever consider their significance in the surroundings?

The American Pyrotechnics Association reported that in 2017, 254.4 million pounds of fireworks were consumed [1]. Never mind that there were almost 13,000 injuries reported from fireworks, but looking at National Fire Protection Association recurring statistics from only a few years ago, almost 16,000 fires were reported from fireworks [2].

Even better, close to $1 billion Americans spend on fireworks goes to China where 99% of the backyard shows and 70% of public displays are produced [3]. China was the first to use fireworks anyway.

Related image
The World Science Festival depiction of the parts of a firework.

Whether or not you’ve read the previous post, to understand what chemicals we’re talking about, you have to know how a firework works and what it contains.

An aerial shell is a cardboard-wrapped, dextrin-bound package of the burst charge containing explosive gun powder (sulfur and charcoal as fuel and potassium nitrate (saltpeter) as oxidizer) in the core which produces large amounts of hot solids and gases (potassium sulfide, potassium carbonate, potassium sulfate, nitrogen, sulfur dioxide, carbon monoxide, and carbon dioxide-of course). The stars are tiny pallets of chemical compounds that give fireworks their color and configuration depending on their placement within the gunpowder complete with quantities of gunpowder to vary the heat and duration of the burst [4].

The shell is propelled from within the mortar tubes once the main fuse (made of a gunpowder core wrapped in textile and coated in wax) is lit and the lift charge of the shell containing calculated amounts of gunpowder is reached.

The mortar pipes, made of high-density polyethylene, fiberglass, or steel and often three times the length of aerial shells but of equal diameter, are there to trap the heat and gas pressure (often at 250 psi!) from the lift charge until it builds up to a force that hurls the firework high into the air. The larger the shell, the larger the tube, the higher the altitude it reaches.

Meanwhile, the time delay fuse burns throughout the flight of the firework and sets off the layers of explosive and stars set apart by protective disks made of cardboard in a rapid explosive show in the sky.

The metal salts, by incandescence, rid of energy absorbed from combustion in the form of light – thus the colorful display. PBS’s NOVA provides that magnesium or aluminum are used for white, sodium salts for yellow, strontium nitrate or carbonate for red, barium nitrate for green, copper salts for blue, and charcoal or other forms of carbon for orange.

The strontium compounds used for red fireworks which hurtle back to earth dissolve in the ground or water, or in children – impacts bone growth.

Blue fireworks from copper are accompanied by the formation of dioxins, identified human carcinogens shown to lead to chloracne (a skin disease), and hormone production and glucose metabolism abnormalities.

The greens use barium, which causes gastrointestinal problems like diarrhea and muscular weakness ranging from breathing trouble to paralysis when found in large quantities in drinking water.

Lastly, the cadmium which aids various colors is another known human carcinogen known to damage kidneys, lungs, bones, and the stomach [5].

Colorful fireworks and their composition; courtesy of the World Science Festival.

The ingestion of these and more even by the smallest organisms is known to allow these substances to move up in the food chain. The demand for deeper and clearer colors of fireworks in the sky can only increase the presence of these dangers in our bodies.

Enough about the colors; remember the thrilling booms you could feel in your stomach at these magnificent shows?

A sonic boom accompanies a firework launch, produced by the expansion of gases underneath the shell at around 330 ms¯¹ and sometimes faster than the speed of sound!

The acoustics of fireworks depend on additives, either slow-burning gun-powders or fast-burning powders like potassium perchlorate or powdered metals like aluminum or magnesium [6].

Not only does the noise and light pollution upset domestic animals, but the contribution by fireworks negatively impacts wildlife, as documented by the U.S. Bureau of Land Management and Fish & Wildlife Service while studying the effects of fireworks on birds and other inhabitants of the Town of Gualala in Mendocino County, CA in 2007. The investigation found that the fireworks disturbance resulted in abandonment of nests. Furthermore, the sound from fireworks causes fear, stress, and anxiety in wild animals, causing them to flee into roadways and often resulting in either vehicle damage or dead animals [7].

Fireworks result from oxidation and reduction reactions with oxygen produced by oxidizers like nitrates, chlorates, or perchlorates to burn the reducing agents and excite the atoms of the stars for color.

So where do all these materials end up? Not everything is encompassed in the aerial combustion and damages the air quality.

Misfires or “duds” – dead fireworks – are not the only debris resulting from our shows. Portions of the casing and residue travels by wind and lands on earth. Shows along the shores – the best ones to watch – result in declined water and sediment quality or impact sensitive habitat areas if not cleaned up properly [8].

Speaking of wildlife again, waterfowl become entangled in remnants of large fireworks, or ingest pieces, and scavenging animals (both birds and mammals ingest debris, large enough to be lethal) [7]. Aside from the size of particles, toxic materials end up in the air – inhaled by wildlife and ourselves or absorbed by the natural environment.

On a smaller scale, the firework smoke produced contains fine particulate matter (PM 2.5) pollution that significantly damages the air. The metal and chemical enhanced smoke can contribute to lung inflammation, heart attacks, strokes, asthma attacks, and reduced lung function.

The spikes in particulate matter in the air even forced the EPA to issue an “interim guidance” to help air quality agencies manage large fireworks displays as an exception to air quality in order to maintain National Ambient Air Quality Standards (NAAQS) under the Clean Air Act.

UCLA Law authors expand on how these toxic components, like lead, barium, ammonium perchlorate, and sulfur dioxide in the firework shell, contribute to long-term water quality and human health degradation. Following fireworks, levels of water pollutants such as arsenic, copper, and phosphorous elevate, affecting surface water and bottom-dwelling organisms. Similarly, the increased levels of perchlorate in water, especially drinking water, can interfere with thyroid function in humans, affecting metabolism and growth, and even accelerate the eutrophication of lakes as nutrients feed algae and bacteria but deprive lakes of oxygen for other life.

Ultimately, with global warming and increased universal entropy, Independence-Day celebrators, Diwali observers, and New Year romantics need greener fireworks if we want to keep the health of our environment until the next celebration.

Part of it comes from diagnosis of the issue.

Reporting the site of a fireworks display helps local officials mitigate the after-effects like worsened air and water quality of a show. Using lawful products which adhere to safe fireworks standards with manageable amounts of the chemicals and gunpowder also help maintain environmental equilibrium.

The second, and most potent part, comes from action.

The first step would be cleaning up after the show, as many communities already ensure to do so.

Else, be like Disney. Disney, starting in 2004, began using air-pressured fireworks for their shows, thus reducing the particle pollution in their area.

Perchlorate-free, Chlorine-free, and Lead-free fireworks are also populating store shelves.

Image result for lasershow stone mountain
Lasershow at Stone Mountain in Georgia. Courtesy of Mountainvision.


Alternatively, forgo these explosions. The near-nightly fireworks displays at resorts are as harmful as they are beautiful, so do petition for better fireworks regulations for large companies. However, in cases like the 4th of July – which has been celebrated in this way for over two centuries – leaving fireworks out is understandably extreme. While it is counter-intuitive to worsen the global health in celebration of the heroes who fought for borders and freedoms that we won’t be able to enjoy in the future, the least we can do is contribute to invention of healthier fireworks displays, opt in for laser light shows, and attend public shows instead of hosting our own.

While all of these warnings still require further research, reflect on this past 4th of July and make it a goal to make a change by the next time you enjoy a light show.

Do you still need this old-fashioned pyrotechnology to be the backdrop of every celebration just because the real stars can’t penetrate the air and light pollution built up?


[1] Admin, MemberClicks. “Industry Facts & Figures.” American Pyrotechnics Association, http://www.americanpyro.com/industry-facts-figures

[2] “Fireworks.” NFPA, https://www.nfpa.org/News-and-Research/Fire-statistics-and-reports/Fire-statistics/Fire-causes/Fireworks

[3] Horsley, Scott. “For Independence Day Fireworks, U.S. Depends On China.” NPR, NPR, 3 July 2018,  https://www.npr.org/2018/07/03/625405653/for-independence-day-fireworks-u-s-depends-on-china

[4] JohnBernard, et al. “What’s Happening Inside Those 4th of July Fireworks.” World Science Festival, https://www.worldsciencefestival.com/infographics/boom-science-behind-fourth-july-fireworks/

[5] McLendon, Russell. “Are Fireworks Bad for the Environment?” MNN – Mother Nature Network, Mother Nature Network, 3 July 2018, https://www.mnn.com/earth-matters/translating-uncle-sam/stories/are-fireworks-bad-for-the-environment

[6] Russel, Michael S. The Chemistry of Fireworks. Royal Society of Chemistry, 2015.

[7] “WSWS – Fireworks and Wildlife.” WSWS – Baby Animals, https://www.westsoundwildlife.org/wildlife/Coexisting/CO_Fireworks.html

[8] “Bombs Bursting in Air: Environmental Regulation of Fireworks.” Legal Planet, 3 July 2013, http://legal-planet.org/2013/07/03/bombs-bursting-in-air-environmental-regulation-of-fireworks/

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