Fireworks have been part of American Independence Day celebrations since independence itself. John Adams started the tradition on July 3, 1776, the day after independence was declared (but a day before the declaration’s wording was agreed). He wrote to his wife that the event
“ought to be commemorated, as the Day of Deliverance by solemn Acts of Devotion to God Almighty. It ought to be solemnized with Pomp and Parade, with Shews, Games, Sports, Guns, Bells, Bonfires and Illuminations from one End of this Continent to the other from this Time forward forever more.”
“Illuminations” have been associated with the Fourth of July ever since. But while awesome, they are also dangerous, and not just because they cause thousands of injuries and several deaths a year, but also because they’re heavy polluters.
California’s San Joaquin Valley is among the most polluted areas in the US. Every year, monitors placed around the valley see levels of PM2.5—the fine particles that are the worst for your lungs, and can’t be blocked by ordinary dust masks—reach unhealthy levels after the fireworks. A study reported by ChinaDaily USA found that “within one hour of a fireworks display, levels of copper in the air increased six fold, potassium 11 fold, barium 12 times, magnesium 22 times and strontium a staggering 120 fold.”
Moreover, the ingredients that make the pretty colors in fireworks—such as compounds of barium (green), copper (blue), or lithium or strontium (red)—can be carcinogenic if they accumulate in the bloodstream. The Lancet warns that firework-generated pollution can have “great consequences for health,” particularly in areas where the levels of PM2.5 are already high. In many Chinese cities, the already-hazardous levels of pollution reach up to 40 times the US safety standard after fireworks.
Air pollution in the US isn’t yet at Chinese levels. What the San Joaquin Valley considers very dangerous is considered moderate in urban China. But it is hazardous nonetheless.