It’s no secret that fireworks can cause some serious air pollution, in the United States as well as in other countries where holiday displays are common, like China and India. But not everyone is equally at risk from the noxious particles that suffuse the sky during our pyrotechnic light shows. In California, for example, vulnerable populations are more exposed to fireworks pollution on the Fourth of July.

That’s according to a recent study published in the International Journal of Environmental Research and Public Health on air pollution exposure across the state due to Independence Day fireworks. At its peak, the smoke from these events can be comparable to that from wildfires, the study found.