New research suggests that dogs have a higher chance of biting people during hotter or sunnier days and when air pollution levels are higher.
According to the new study, there's an 11% increase in the probability that dog bites occur during these conditions.
Another study says that humans commit more violent crimes when temperatures are higher. It suggested that there's a connection between the hot weather and higher levels to the increase in aggression in humans, Rhesus monkeys, rats, and mice.
Research in the Scientific Reports journal stated:
“We conclude that dogs, or the interactions between humans and dogs, are more hostile on hot, sunny, and smoggy days, indicating that the societal burden of extreme heat and air pollution also includes the costs of animal aggression.”
Clas Linnman and colleagues at Harvard Medical School examined data on dog bites in eight US cities: Dallas, Houston, Baltimore, Baton Rouge, Chicago, Louisville, Los Angeles, and New York City, between 2009 and 2018.
The team found that dog bites increased by 11% on days with higher UV levels and 4% on days with increased temperatures. They also found that it increased by 3% on days with higher ozone levels.
For comparison, during the rainy season, dog bite incidences slightly decreased by only 1%.
Researchers also said there were no changes in dog bite occurrence on days with higher levels of fine particular matter (PM2.5- an air pollutant).
However, the authors caution that the dog bite records did not include information about other aspects affecting a dog's individual risk of biting, like the dog's breed, sex, or whether or not the dog has been neutered or spayed.
There was also no information about prior interactions between the dog and the victim, whether the person knew the dog and interacted with the dog often or not.
According to the researchers, further study is needed to verify the connection between dog aggression and higher temperatures and air pollution.