Short-term association between ambient temperature and homicide in South Africa: a case-crossover study

Abstract

BackgroundCriminology research has traditionally investigated sociodemographic predictors of crime, such as sex, race, age, and socioeconomic status. However, evidence suggests that short-term fluctuations in crime often vary more than long-term trends, which sociodemographic factors cannot explain. This has redirected researchers to explore how environmental factors, such as meteorological variables, influence criminal behavior. In this study we investigate the association between daily ambient temperature and homicide incidence in South Africa, a country with one of the highest homicide rates in the world.MethodsMortality data was from South Africa’s civil registration system and includes all recorded deaths in the country from 1997 to 2013 (17 years). Daily temperature was from the National Oceanographic and Atmospheric Association of the United States and South Africa’s Agricultural Research Council. Data were analyzed using a time-stratified case-crossover design with conditional logistic regression. We delineated cases as either “definite” (ICD-10 codes X85-Y09, n = 68,356) or “probable” homicides (ICD-10 codes W25-W26, W32-W34, W50, Y22-Y24, Y28-Y29, n = 177,873). Case periods were defined as the day on which a death occurred. Control periods were selected using a day-of-week match within the same month and district. Analyses investigated same-day and lagged effects of maximum, mean and minimum temperature.ResultsA one-degree Celsius increase in same-day maximum temperature – our a priori metric of choice – was associated with a 1.5% (1.3–1.8%) increase in definite homicides and a 1.2% (1.1–1.3%) increase in total (definite + probable) homicides. Significant (p < 0.05) positive associations were also observed when applying other temperature metrics (mean, minimum) and lags (1, 0–1). The shape of the association did not display any clear non-linearities. There was no evidence of confounding by public holidays or air pollution.ConclusionsThis study suggests a positive association between daily ambient temperature and homicide in South Africa. This temperature-health relationship may be of particular concern in the context of climate change. The ability to include meteorological variables as a predictor of criminal activity and violent behavior could prove valuable in resource allocation for crime prevention efforts.

Vulnerable, Resilient, or Both? A Qualitative Study of Adaptation Resources and Behaviors to Heat Waves and Health Outcomes of Low-Income Residents of Urban Heat Islands

“…In this study, a majority of participants reported one or more physical symptoms of heat exposure, and close to three of every four residents reported mental health symptoms during a heat wave, largely due to uncertainty, confinement, and a sense of desperation. These findings are consistent with studies linking heat waves to increased respiratory and cardiovascular morbidity and mortality as well as suicidal and homicidal behavior [ 20 , 21 , 22 , 23 , 24 , 25 ] and increased monthly temperatures of 30C and higher to greater mental health difficulties [ 16 ]. However, only two of the participants sought medical attention for these problems.…”

“…For instance, low-income residents of urban heat islands are more susceptible to heat-related morbidity and mortality due to increased temperatures, lack of tree cover and green space, low socioeconomic status, lack of material resources, and low saturation of air conditioning (AC) [ 9 , 10 , 11 , 12 , 13 , 14 ]. Heat waves and rising temperatures have also been linked to increased negative emotions and stress [ 14 , 15 , 16 ], hospitalizations for mood and behavioral disorders [ 17 ], mortality in patients with mental and behavioral health disorders [ 18 , 19 ], and increased rates of suicide [ 20 , 21 , 22 , 23 ] and homicide [ 24 , 25 ].…”

The Effects of Daily Temperature on Crime Events in Urban Hanoi, Vietnam Using Seven Years of Data (2013–2019)

“…Hanoi’s urban structure and boundary were expanded in 2008, and policies have strongly promoted population density and social development [ 12 ]. Moreover, in contrast to other urban areas in which studies of temperature and crime have been conducted, our data indicate that Hanoi has much lower crime rates than urban areas in other parts of the world, with an average crime count of 1.52 per day, compared to 39.7 in South Africa or 135 in Baltimore, Maryland [ 6 , 17 ], although this may be partially attributable to differences in policing and crime reporting.…”

“…Little research has been conducted in developing countries to examine the effects of temperature on crime, and no study has been conducted in Vietnam. Gates et al found an increase in homicides for each 1 °C in maximum temperature in South Africa [ 6 ]. However, Trujillo et al indicated that each 1 °C in maximum temperature is associated with a 0.8% increase in interpersonal violence but decrease in homicides in Colombia [ 7 ].…”

Protecting health in dry cities: considerations for policy makers

“…Some evidence links high temperatures with aggressive behavior, violent crime, and possibly suicide. 65 66 67 68 Such societal tension can escalate into armed conflict. In addition, several dry cities are in areas with already fragile states.…”