Air pollution may be fueling delinquency and bad behavior among teenagers, according to new research.
Evidence of the detrimental effects of pollution has long been building, and this large study shows strong link between pollution and behavioral traits that may be caused by underlying changes to the brain.
Tiny, toxic particles are damaging to the neurons responsible for emotions and decision-making, and nearly 75 percent of Los Angeles teens in the study were exposed to unhealthy levels of them.
Scientists from the University of Southern California say this is because they creep into developing brains, causing inflammation and ultimately leading to anti-social behavior.
Air pollution, which is more concentrated in urban areas like Los Angeles (pictured), may cause inflammation in developing brains, leading to bad behavior in teens (file image)
A study of almost 700 people under 19 found those most exposed to traffic fumes were more likely to indulge in anti-social behavior while growing up.
These behaviors included lying and cheating, truancy, stealing, vandalism, arson or substance abuse.
Lead author Dr Diana Younan of the University of Southern California said it could be having the same effect on young people as exposure to lead, which has also been linked to juvenile delinquency.
The discovery adds to growing evidence of the grave harm pollution can do to the brain – especially when it’s still developing.
Previous research has shown connections between air pollution and an increased risk of mental illness among children and dementia and strokes among older people.
Dr Younan said that PM2.5s – fine particulate matter made up of dust and soot – are known to be extremely harmful to both physical and mental health.
‘These tiny, toxic particles creep into your body, affecting your lungs and your heart,’ Dr Younan, a preventive medicine research associate at the university’s Keck School of Medicine, 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.’
The particles are 2.5 micrometers or smaller – enabling them to enter a person’s lungs through the respiratory system.
They are released from car exhausts, for example, as well as other industrial, domestic and natural sources.
Dr Younan said: ‘Previous studies by others have shown early exposure to lead disrupts brain development and increases aggressive behavior and juvenile delinquency.
‘It’s possible 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.’
This means cleaner air and the need more parks in urban spaces. Air pollution was highest near freeways and in neighborhoods with limited green space or foliage, and those who lived in these areas were also more likely to exhibit delinquent behavior.
The study, published in the Journal of Abnormal Psychology, followed 682 participants for nine years – starting when they were just nine.
Parents completed a behavior checklist every few years and noted if their child had engaged in 13 rule-breaking behaviors, with up to four assessments recorded.
The researchers used 25 air quality monitors to measure daily pollution in Southern California from 2000 to 2014 with a computer analysis comparing each participant’s home address with PM2.5 levels outside.
About three quarters of the teens breathed ambient air pollution that exceeded the US government’s recommended levels of 12 micrograms per cubic meter.
In some areas, the pollution was nearly double those levels.
Senior author Professor Jiu-Chiuan Chen, based in the same lab, said air pollution is triggering more than just lung and heart conditions.
He said: ‘It’s widely recognized ambient air pollution is detrimental to the respiratory and cardiovascular health of young and old alike.
‘But in recent years scientists have come to acknowledge the negative impact of air pollution on human brains and behaviors.’
It has been suggested air pollution could increase levels of crime in communities.
The researchers noted that both ambient PM2.5 concentration and crime rates in Southern California have been on the decline.
They called for future studies to examine whether it’s mere coincidence or if tightened air regulation might have contributed to the trend.
Dr Younan said: ‘Poor people, unfortunately, are more likely to live in urban areas in less than ideal neighborhoods.
‘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 they are more likely to engage in delinquent behavior.’
Rates were also worse in boys, African Americans and adolescents from poorer families.
The bad behaviors linked to air pollution were magnified when children did not have good relationships with their parents, lived with depressed mothers or grew up in homes with higher levels of parental stress.
Dr Younan added that those that live in pollution-prone areas should ‘try to avoid being outside so much and keep windows closed as much as possible when the ambient PM2.5 levels are high.
‘Try to compensate for air pollution by having a good indoor environment and healthy family dynamics.
‘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,’ she said.
In more than two decades of previous research, her lab has found air pollution increases obesity and that teenagers in urban communities with less parks tend to be more aggressive.