By: Vivian H. Lyons, Emma L. Gause, Keith R Spangler, et al.

Importance: Firearm violence is a leading public health crisis in the US. Understanding whether and how ambient temperature is associated with firearm violence may identify new avenues for prevention and intervention.

Objective: To estimate the overall and regional association between hotter temperatures and higher risk of firearm violence in the US.

Design, setting, and participants: This cross-sectional study used distributed lag nonlinear models, controlling for seasonality and long-term time trends by city and pooled results overall and by climate region. The most populous cities in the US with the highest number of assault-related firearm incidence (ie, shootings) from 2015 to 2020 were analyzed. Data analysis was performed from October 2021 to June 2022.

Exposures: Maximum daily temperature by city.

Main outcomes and measures: The primary outcome was the number of assault-related firearm shootings by city.

Results: A total of 116 511 shootings in 100 cities were included in this analysis. The pooled analysis estimated that 6.85% (95% CI, 6.09%-7.46%) of all shootings were attributable to days hotter than city-specific median temperatures. This equates to 7973 total shootings (95% CI, 7092-8688 total shootings) across the 100 cities over the 6-year study period, although the number of total persons injured or killed would be higher. Estimated risk of firearm incidents increased almost monotonically with higher temperatures, with a local peak at the 84th percentile of the temperature range corresponding to a relative risk of 1.17 (95% CI, 1.12-1.21) compared with the median temperature. However, even moderately hot temperatures were associated with higher risk of shootings. Although significant, there was low heterogeneity between cities (I2 = 11.7%; Cochran Q test, P = .02), indicating regional or climate-specific variation in the daily temperature and incident shootings relationship.

Conclusions and relevance: These findings underscore the importance of heat adaptation strategies broadly throughout the year to reduce shootings, rather than focusing on only the hottest days.

JAMA Netw Open. 2022 Dec 1;5(12):e2247207. doi: 10.1001/jamanetworkopen.2022.47207. PMID: 36525273; PMCID: PMC9856408.

By Charles C Lanfear , Rebecca Bucci , David S Kirk , Robert J Sampson

Importance: The past quarter-century has seen both sharp declines and increases in firearm violence in the United States. Yet, little is known about the age of first exposure to firearm violence and how it may differ by race, sex, and cohort.

Objective: To examine race, sex, and cohort differences in exposure to firearm violence in a representative longitudinal study of children who grew up in periods with varying rates of firearm violence in the United States and to examine spatial proximity to firearm violence in adulthood.

Design, setting, and participants: This population-based representative cohort study included multiple cohorts of children followed-up from 1995 through 2021 in the Project on Human Development in Chicago Neighborhoods (PHDCN). Participants included Black, Hispanic, and White respondents from 4 age cohorts of Chicago, Illinois, residents, with modal birth years of 1981, 1984, 1987, and 1996. Data analyses were conducted from May 2022 to March 2023.

Main outcomes and measures: Firearm violence exposure, including age when first shot, age when first saw someone shot, and past-year frequency of fatal and nonfatal shootings within 250 m of residence.

Results: There were 2418 participants in wave 1 (in the mid-1990s), and they were evenly split by sex, with 1209 males (50.00%) and 1209 females (50.00%). There were 890 Black respondents, 1146 Hispanic respondents, and 382 White respondents. Male respondents were much more likely than female respondents to have been shot (adjusted hazard ratio [aHR], 4.23; 95% CI, 2.28-7.84), but only moderately more likely to have seen someone shot (aHR, 1.48; 95% CI, 1.27-1.72). Compared with White individuals, Black individuals experienced higher rates of all 3 forms of exposure (been shot: aHR, 3.05; 95% CI, 1.22-7.60; seen someone shot: aHR, 4.69; 95% CI, 3.41-6.46; nearby shootings: adjusted incidence rate ratio [aIRR], 12.40; 95% CI, 6.88-22.35), and Hispanic respondents experienced higher rates of 2 forms of violence exposure (seen someone shot: aHR, 2.59; 95% CI, 1.85-3.62; nearby shootings: aIRR, 3.77; 95% CI, 2.08-6.84). Respondents born in the mid-1990s who grew up amidst large declines in homicide but reached adulthood during city and national spikes in firearm violence in 2016 were less likely to have seen someone shot than those born in the early 1980s who grew up during the peak of homicide in the early 1990s (aHR, 0.49; 95% CI, 0.35-0.69). However, the likelihood of having been shot did not significantly differ between these cohorts (aHR, 0.81; 95% CI, 0.40-1.63).

Conclusions and relevance: In this longitudinal multicohort study of exposure to firearm violence, there were stark differences by race and sex, yet the extent of exposure to violence was not simply the product of these characteristics. These findings on cohort differences suggest changing societal conditions were key factors associated with whether and at what life stage individuals from all race and sex groups were exposed to firearm violence.

JAMA Network Open 6(5); 2023

By United States. Federal Bureau Of Investigation

From the document: "In 2013, the president signed into law the Investigative Assistance for Violent Crimes Act of 2012, which led the FBI to examine active shooter incidents since 2000. The findings in this report are intended to provide an overview of active shooter incidents to help law enforcement, other first responders, and the public better understand the levels of threats associated with active shooter incidents. In 2022, the FBI designated 50 shootings as active shooter incidents. Although incidents decreased by 18% from 2021 (61 incidents), the number of active shooter incidents increased by 66.7% compared to 2018 (30 incidents). The 50 active shooter incidents in 2022 occurred in 25 states and the District of Columbia and represent seven location categories, including open spaces, commerce, residences, education, government, houses of worship, and a health care facility. [...] Data cited in this report for active shooter incidents that occurred in 2022 is valid as of February 10, 2023; however, incident data from prior published reports was not updated. If additional incidents meeting FBI criteria are identified after the publication of this document, every effort will be made to factor those incidents into future reporting."

United States. Federal Bureau of Investigation. 2023. 33p.

By Rajeev Ramchand, Jessica Saunders

Australia’s 1996 National Firearms Agreement (NFA) banned several types of firearms and resulted in the government buying hundreds of thousands of the banned weapons from their owners. Studies examining the effect of removing so many weapons from the community have found that homicides, suicides, and mass shootings were less common after the NFA was implemented, although such incidents were declining prior to 1996. The strongest evidence is consistent with the claim that the NFA caused reductions in firearm suicides, mass shootings, and female homicide victimization. However, there is also evidence that raises questions about whether, for at least firearm suicides, those changes can be attributed to the NFA or to other factors that influenced rates of these outcomes around the time the NFA was implemented.

Rand Corp. 2021. 27p.

By Rosanna Smart, Terry L. Schell

There is no standard definition of what constitutes a mass shooting, and different data sources—such as media outlets, academic researchers, and law enforcement agencies—frequently use different definitions when discussing and analyzing mass shootings. For instance, when various organizations measure and report on mass shootings, the criteria they use in counting such events might differ by the minimum threshold for the number of victims, whether the victim count includes those who were not fatally injured, where the shooting occurred, whether the shooting occurred in connection to another crime, and the relationship between the shooter and the victims. These inconsistencies lead to different assessments of how frequently mass shootings occur and whether they are more common now than they were a decade or two ago. Data show that, regardless of how one defines mass shootings, perpetrators are likely to be men. But several other characteristics that are statistically predictive of perpetration are still uncommon among offenders on an absolute level. The rare nature of mass shootings creates challenges for accurately identifying salient predictors of risk and limits statistical power for detecting which policies may be effective in reducing mass shooting incidence or lethality. Implementing broader violence prevention strategies rather than focusing specifically on the most-extreme forms of such violence may be effective at reducing the occurrence and lethality of mass shootings.

Santa Monica, CA: RAND, 2021. 32p.