(CN) – Tiny, toxic particles in the air that creep into developing brains and cause inflammation that damage the pathways responsible for emotion and decisions may be to blame for increased teenage delinquency, a new study says.
The new study, published Wednesday in the Journal of Abnormal Psychology, links higher levels of air pollution to bad behavior in teens and is a reminder of the importance of clean air and the need for more foliage in urban spaces, according to researchers at the Keck School of Medicine at the University of Southern California.
Ambient air pollution may increase delinquent behavior among 9 to 18-year-olds in urban neighborhoods in Greater Los Angeles, the study suggests. These effects are then compounded by poor parent-child relationships and parental mental and social distress.
Tiny pollution particles called PM2.5 – 30 times smaller than a strand of hair – are extremely harmful to your health, according to Diana Younan, preventive medicine research associate at the Keck School of Medicine and lead author of the study.
“A bad parent-child relationship causes a stressful family environment, and if this goes on for too long, the teenager could be in a chronic state of stress. This could wreak havoc on the body, making teens more vulnerable to the effects of exposure to small particles. Many scientists suspect PM2.5 causes inflammation in the brain or somehow travels directly into the brain and messes with neural network connections, resulting in the observed bad behaviors,” Younan explained.
For more than 20 years Younan and colleagues at the USC Environmental Health Sciences Center collaborated with university researchers and engineers from different disciplines to investigate the insidious effects of air pollution. They found that air pollution increases obesity, teenagers in urban communities with less trees and greenspace tend to be more aggressive and older women living in areas with higher than standard particulate matter levels had nearly double the risk for dementia when compared to their counterparts.
“These tiny, toxic particles creep into your body, affecting your lungs and your heart,” Younan said.
“Studies are beginning to show exposure to various air pollutants also causes inflammation in the brain. PM2.5 is particularly harmful to developing brains because it can damage brain structure and neural networks and, as our study suggests, influence adolescent behaviors.”
Younan drew similarities between her study and previous studies by others that have shown early exposure to lead, like from paint in older homes, disrupts brain development and increases aggressive behavior in juveniles.
“It’s possible that growing up in places with unhealthy levels of small particles outdoors may have similar negative behavioral outcomes, though more research is needed to confirm this. Both lead and PM2.5 are environmental factors that we can clean up through a concerted intervention effort and policy change,” Younan added.
The 9-year study study followed 682 children in the LA area. Parents completed a child-behavior checklist every few years and noted if their child had engaged in 13 rule-breaking behaviors, including lying and cheating, truancy, stealing, vandalism, arson, or substance abuse. Up to four assessments were recorded per participant.
Researchers measured daily air pollution in Southern California from 2000 to 2014 using 25 air quality monitors. They computed each participant’s residential address and used mathematical modeling to estimate the ambient PM2.5 levels outside each home. About 75 percent of the participants breathed ambient air pollution that exceeded the federal recommended levels of 12 micrograms per cubic meter. Some areas had nearly double the recommended amount.
“It is widely recognized that ambient air pollution is detrimental to the respiratory and cardiovascular health of young and old alike, said Jiu-Chiuan Chen, an associate professor of preventive medicine at the Keck School of Medicine and senior author of the study.
Chen acknowledged, however that only in recent years have scientists connected the negative impact of air pollution on human brains and behaviors.
Environmental scientists and economists have speculated that elevated air pollution levels could increase criminal activities in communities. Data show that both ambient PM2.5 concentration and crime rates in Southern California have been on the decline, the study stated.
Researchers caution future studies will need to examine whether that is mere coincidence or if tightened air regulations might have contributed to the declining crime rates in many metropolitan areas.
The study identified higher air pollution estimates near freeways and in neighborhoods with limited green space or foliage. These locations also tend to have residents with lower incomes.
“Poor people, unfortunately, are more likely to live in urban areas in less than ideal neighborhoods,” Younan added. “Many affordable housing developments are built near freeways. Living so close to freeways causes health problems such as asthma and, perhaps, alters teenagers’ brain structures so that they are more likely to engage in delinquent behavior.”
Researchers noticed more delinquent behavior from boys, African-Americans, adolescents from lower socioeconomic backgrounds and people who lived in downtrodden neighborhoods with limited green space when compared to their counterparts.
Study scientists recommend those who have no choice in where they live, are near freeways or surrounded by little greenery, to compensate for air pollution by having a healthy indoor environment and family dynamics. It helps to also avoid being outside as much and keep windows closed when the ambient PM2.5 levels are high, they say.
Catherine Tuvblad and Laura A. Baker from USC; Meredith Franklin, Lianfa Li and Kiros Berhane from the Keck School of Medicine; Fred Lurmann from Sonoma Technology; and Jun Wu from the University of California, Irvine, contributed to the study.
The research was fully funded by the federal government through grant funds from the National Institute of Environmental Health Sciences and the National Institute of Mental Health.