Why You Should Always Close Your Windows During Fireworks

Love them or hate them, fireworks have been an American fourth of July staple since 1777. And while the displays have become more elaborate since then, the basic composition of fireworks—gunpowder and chemicals put into a casing with a fuse attached—hasn’t changed all that much in the last 245 years. Unfortunately, neither have the clouds of smoke visible after a firework has fizzled out.

As you can imagine, the contaminants in this smoke aren’t great for air quality. And if you live near the site of a fireworks display, you’re probably in the path of some of that pollution. Here’s what to know about how fireworks can impact indoor air quality, and why you may want to close your windows the evening of July 4.

Do fireworks cause air pollution?

When we think about fireworks safety, it’s usually in terms of avoiding injuries and fires. But the effects of the celebratory explosives on air quality is also a safety concern. That’s because when fireworks are ignited, they release gaseous sulfur dioxide, carbon dioxide, and carbon monoxide, along with hazardous trace elements like aluminum, manganese, and cadmium. Plus, there’s the particulate matter (PM)—exposure to which can affect our respiratory and cardiovascular systems.

Do fireworks affect indoor air quality?

Of course, this depends on your proximity to a fireworks display and the direction of the wind that evening, but yes: At least two studies have measured abnormally high concentrations of PM during and after fireworks.

In the most recent study, published in the journal Science of the Total Environment in July 2021, researchers measured PM concentrations inside buildings near both public and private fireworks displays, and noted that the air reached unhealthy levels “almost immediately,” and could linger for hours.

How to protect the air quality inside your home during fireworks

Keep in mind that the air pollution resulting from fireworks is combination of smoke and PM resulting from chemical reactions—and both can affect your indoor air quality, the authors of the 2021 study point out. Here are are a few strategies for keeping the bad air out of your living space: