Spectacular firework displays will mark the start of the New Year, but air quality will plummet

Millions of fireworks are set off around the world each year to mark New Year's Eve, causing air pollution to spike. Should you be worried?

As clocks around the world toll midnight on 31 December 2024, spectacular firework displays will fill the skies to mark the dawn of a new year. Above Sydney Harbour – which hosts one of the world's largest New Year fireworks shows – nine tonnes of sparklingly, smoking explosives will launched in two separate displays on the night.  

In London, up to 12,000 fireworks are blasted into the sky each year – although bad weather threatened to put a stop to the annual display in the city this year and shows in other parts of the UK were cancelled due to high winds, including the famous Hogmanay celebrations in Edinburgh.

A temporary ban on fireworks in New York City has also been lifted in time for New Year's Eve, while in Las Vegas, a chain of fireworks will be fired from the rooftops of 10 of the city's landmark hotels and casinos. 

Each year, in fact, Americans set off nearly 300 million lbs (136,000 tonnes) of fireworks – nearly one pound for every person living in the US. Europe imports around 30,000 tonnes (66 million lbs) of fireworks each year, although that figure is down dramatically from 110,000 tonnes (253 million lbs) of fireworks in the years prior to the pandemic. Globally, the firework industry is booming – the market size was valued at $2.69bn (£2.14bn) in 2024 and is projected to reach $3.65bn (£2.91bn) by 2032.  

That's a lot of explosions and airborne sparkles – but also a lot of smoke and debris that can not only harm the planet, but also has the potential to damage the lungs of people nearby too. Studies have shown that every year, after major fireworks events to mark New Year's Eve, 4 July, Diwali and many others, air quality can plummet due to the pollution these displays throw into the atmosphere. But how much harm do they really do?

Fireworks are thought to have originated in China during the 2nd Century BC with the invention of gunpowder before spreading around the world. Modern chemistry has since transformed them into ever more spectacular forms, introducing new effects and colours to their loud explosions. But as their use as a celebratory crowd-pleaser has increased, it has also become clear that they can affect wildlife, the environment and potentially also human health.

Most attention about the dangers of fireworks focuses on the injuries and burns caused by explosions in accidents, or incidents of deliberate misuse. Certainly, firework-related injuries have increased in recent years.

But there are other far-reaching effects of these celebratory spectacles, especially when set off in large displays like those at New Year and on 4 July celebrations in the US. While fireworks generate large amounts of smoke, which can have an often visibly negative impact on air quality, they also release other pollutants that are harder to see.

Peter Brimblecombe, a professor of environmental sciences at the University of East Anglia, in the UK, but who lives in Waikiki, Hawaii, published a paper in 2023 analysing how fireworks can also contribute to particulate pollution in the air above the city of Honolulu. He found that overnight into New Year's Day, there is a significant increase in airborne particulates above the city, which he says far outstrips the number of permits bought for fireworks on the night. Much of it, he suspects, comes from illegally purchased fireworks, instead.

A study of particulate air pollution in the cities of Brno, in the Czech Republic, and Graz, in Austria, showed large but temporary spikes in this type of air pollution between midnight and 6am on New Year's Day. Metals and alloys typically used in the fuel and colourants of fireworks were particularly present within the particulate pollution. 

Another study, which took place in Germany over 11 years, found a "drastic" increase in concentrations of the particles on New Year's Days. Further research found around 80% of the particulate matter emitted by the fireworks is respirable – meaning they can reach the lungs. These fine soot particles have been linked to a range of health problems including asthma, heart disease and low birth weight.  

But it isn't just restricted to New Year. In some areas, the concentration of fine particulate pollution known as PM2.5 can be between 1.5 and 10 times higher than normal on the night of 4 July and the following day, according to one study of air quality in California in 2019 and 2020. Another study of 315 sites across the US in 2015 showed that PM2.5 concentrations were on average 42% higher nationally during the 4 July holiday. The worst affected areas – those that were closest to large firework displays – saw the PM2.5 concentration nearly quadruple. But the pollution is usually short-lived and tends to diminish by noon the following day.

"Definitely, pollutant loads increase during the events," says Brimblecombe. "Poor air quality and the associated health risks have been part of New Year's Eve on Oahu [in Hawaii] for many years. And it remains a problem that continues to draw attention."

In his own study, Brimblecombe found a "sharp rise" in the PM2.5 concentration during firework celebrations.

Fireworks also release a large amount of other air pollutants, particularly sulphur dioxide, carbon dioxide and carbon monoxide alongside particulate matter. Heavy metals, which give fireworks their bright colours, are also often toxic and tests in mice have shown particulate pollution containing these can be harmful. One recent study of air pollution in northern Utah by researchers at Brigham Young University in Provo, Utah, found that concentrations of metals such as copper, potassium, barium, chromium, vanadium and strontium spiked during holidays due to smoke from fireworks. Similar spikes in these elements were found after New Year's fireworks in Graz and Brno.

Individuals exposed to high levels of air pollutants have shown increased prevalence of chronic cough, phlegm and breathlessness – and are therefore at an increased risk of developing asthma, lung cancer, and other respiratory diseases. But there isn't necessarily a direct link between fireworks and long-term health impacts – although pyrotechnicians may be exposed to these health issues over the long term, most effects on audiences from fireworks are short-term, says Brimblecombe. 

"The link to health is harder to make, but I think it is more the workers than the general public that suffer," he says. "However, there is some evidence from Iceland that asthma attacks increased, but the statistics are poor as few people live in Iceland. 

Some scientists have estimated that several hundred million people globally are exposed to firework smoke every year, although it is hard to say how accurate that figure really is.

One paper studying how fireworks affect respiratory health noted the need for more research, particularly into how fireworks impact those with asthma and other respiratory diseases. The researchers found that individuals suffering with respiratory conditions should "avoid heavy exposure".

The report added that children are particularly susceptible to the harmful effects of ambient air exposure, with other research in Hungary also showing that particles from fireworks seem to be deposited within their airways at a rate three times that of adults.

Fireworks can also trigger wildfires that lead to far longer lasting and widespread air pollution. One analysis of wildfires on federal land in the US over a 37-year period from 1980 found that 11,294 of nearly 600,000 fires over that period could be attributed to fireworks. New York City's mayor recently announced he was lifting the ban on fireworks to allow the displays during the upcoming New Year Eve's celebrations. The temporary ban had been imposed due to wildfire concerns following a lack of rainfall in the state.

Large wildfires can send pollution high into the atmosphere, causing it to spread over thousands of miles, during which time it can become more toxic. 

But fireworks also generate other waste that lasts far longer once the dazzling explosions fade and the smoke clears.

One study by the US Geological Survey and National Park Service found water samples taken from around Mount Rushmore between 2011-2015 showed elevated levels of perchlorate, which is used as a propellent in fireworks, in the areas where firework displays had taken place on 4 July celebrations between 1998-2009. It also found elevated levels of the chemical in the soil where the fireworks were launched and where rocket debris landed. Another study from 2007 of a lake in Ada, Oklahoma, showed perchlorate levels rose following 4 July fireworks displays by up to 1,028 times  the levels seen in the preceding days. It then took 20-80 days for the contamination to return to background levels. 

There are concerns that this contamination can find its way into drinking water, where high levels of perchlorate can interfere with human thyroid function. The Environmental Protection Agency is now funding a $2.5m (£2m) study to assess just how much perchlorate from fireworks gets into the lakes, rivers and streams around the US.

But there are other problems that stem from the physical debris left behind by fireworks displays. 

"Research on plastic pollution from fireworks is certainly gathering momentum," says Elizabeth Westhead, a bioscientist at the University of East London, UK. Westhead co-authored a study on microplastics levels in the River Thames in London during the New Year period. "[There's] growing evidence about its environmental impact," she says. 

Westhead and her colleagues studied a stretch of the River Thames near Westminster – where the annual New Year fireworks are held – and found microplastics were "significantly higher" in the area following the dramatic fireworks in 2020. The study found microplastics increased by more than 1,000% over a 24-hour period.

"This short-term high influx of microplastics from fireworks will have detrimental impact on the ecology of the river and neighbouring waterways," says the study's lead author Ria Devereux, a sustainability researcher at the University of East London. "I was curious, especially as I didn't come across any literature on microplastics from fireworks. I expected some microplastics, but nowhere near the amount that I found.

"I think we were all in shock that so many microplastics entered the water system from a 15-minute firework event."

The study is significant, Devereux explains, because microplastics and polymer chemicals can be  taken up by aquatic and marine animals, making their way into the food chain.

But getting people to pay attention to the plastic pollution caused by fireworks may take some time, concedes Westhead. "It will take even more time and much more work to influence public opinion on a very popular tradition," she says.

It's a well-known fact that dogs are scared of fireworks. But studies have shown the devastating impact they can have on birds too.

A study tracking Arctic geese in Europe found that on one New Year's Eve the birds suddenly left their sleeping sites and flew to remote areas – up to 500km (311 miles) without rest. And the impacts lasted long after New Year's Eve. The birds never returned to their original sleeping sites. In one extreme case, hundreds of birds, primarily starlings, were found dead on the streets of Rome after a 2021 New Year's Eve firework event. In 2011, around 5,000 dead blackbirds fell from the sky on one single night in a small town in Arkansas, after being frightened out of their nighttime roosting sites and flying into trees and houses. Wildlife officials blamed the deaths on fireworks.

The annual timing of some large-scale firework events, such as 4 July and New Year's Eve, coincides with reproductive and migratory wildlife behaviour,  one study noted, and so may have long-term population effects on the animals. 

Environmentally friendly fireworks do exist – they have a  clean-burning nitrogen-based fuel which create little smoke. There are also attempts to find alternatives to the harmful heavy metals without losing the brightly coloured sparks that make fireworks so appealing. "Quite a lot of emphasis at present on removing heavy metals that have ecosystem impacts has led to less polluting fireworks," says Brimblecombe. 

But, they're still loud.

Laser shows and drones are among the alternatives that have been used – they're reusable, produce no emissions barring the electricity needed to power them, and they're quiet. Drones are not without their drawbacks, though – the companies that put on New Year's Eve displays say drones are too slow to fully replace fireworks. Dones can also disturb wildlife, if they get too close.

As researchers on one study on the impacts of fireworks on urban air quality summarised: "It is up to the local communities involved to decide in a balanced manner whether this form of amusement is worth the risky atmospheric cocktail it generates."

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