A report found that careless human activities are behind about 84% of all wildfires in the US and accounted for 44% of total area burned. This includes abandoned cigarettes, campfires and barbecues that were not put out properly, as well as so-called gender reveal parties – particularly popular in the country where expectant parents use pyrotechnic devices to reveal a baby’s gender. One notable example is the El Dorado fire, where a smoke bomb led to a fire that lasted more than two months and covered over 22,000 acres of southern California. Another study showed that human-sparked fires typically spread about 1.83 kilometres per day, more than twice as fast as lightning-induced fires.