In the future, police and crime prevention agencies can begin to monitor pollution in their cities and provide resources in those areas where pollution is highest on a given day.
This may sound like a scam science fiction movie, but recent findings suggest that this may be a worthwhile practice.
Why? Recent studies show that air pollution is linked to impairments in assessment, mental health issues, poorer performance at school and, perhaps worryingly, higher crime rates.
These results are all the more alarming as more than half of the world's population is affected. Now I live in urban environments – and more of us travel in congested areas than ever before. Amazingly, the World Health Organization (WHO) says that nine in ten of us breathe in dangerous air pollution.
Air pollution causes an estimated seven million deaths each year. But could we add murders soon?
BBC Future considers the evidence.
Watch our animated version of BBC Reel: How Dirty Air Burdens Our Mind
It was in 201
First, he carried out a study examining whether air pollution affects cognitive performance.
Roth and his team studied the students exams on different days – and also measured how much air pollution was in the air on those days. All other variables remained the same: the exams were taken by the same level of education in the same place, but over several days.
He found that the deviation of the average results was amazingly different. The most polluted days correlated with the worst test results. On days when the air quality was the cleanest, the students performed better.
"On days that were more heavily polluted, a significant decrease [of performance] could be detected," says Roth. "Even a few days before and a few days later, we found no effect – in fact, it was only on the day of testing that the test results dropped significantly."
To determine the long-term effects, Roth followed to see what impact this had eight to ten years later. Those who performed worst on the most polluted days were more likely to end up in a lower-ranked university and earned less because the exam was so important to future education. "So if it's a short-term impact of air pollution, it can have a long-term impact in a critical life phase," he says . Another study underpinned Roth's first results in 2016, according to which environmental pollution can affect productivity.
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These findings led to Roth's most recent work. In a 2018 study, his team spent two years analyzing crime data from over 600 London electoral districts and found that on the worst days in both rich and poor areas, other minor offenses were recorded.
It is important to note that this is purely correlational – but Roth has reason to believe that there is a causal relationship.
Crime Increases Wherever the Pollution Cloud Travels
His team also compared very specific areas over time and the following levels of pollution over time. A cloud of polluted air can move depending on the wind direction. This leads the pollution into different parts of the city at random to richer and poorer areas. "We simply tracked this cloud daily and observed what happened to crimes in areas when the cloud arrived, and we've found that the crime rate rises where it rises," he explains.
Even moderate pollution made a difference. "We find that this major impact on crime exists to a degree well below current regulatory standards." In other words, the US Environmental Protection Agency's "good" ratings were still strong with higher ones Crime rates.
While Roth's data did not have a stronger impact on the more serious murder and rape crimes, another 2018 study showed a possible association. The study, conducted by MIT's Jackson Lu, has been studying data for nine years, covering almost the entire US in more than 9,000 cities. It noted that "air pollution predicted six major categories of crime," including manslaughter, rape, robbery, theft of cars and raids. The most polluted cities also had the highest crime rates. This was another correlation study, however, which reflected factors such as population, employment, age and gender – and pollution was still the main predictor of increased crime rates.
Further evidence comes from a study on "delinquent behavior" (including fraud), tails, theft, vandalism, and substance use) in over 682 adolescents. Diana Younan of the University of Southern California and her colleagues looked specifically at PM2.5 – tiny particles that were 30 times smaller than the width of a human hair – and considered the cumulative effect of exposure to these contaminants over a 12-year period. Once again, bad behavior was more likely in areas of higher pollution.
To verify the connection, it could not simply be explained by its socioeconomic status alone. Younan's team also contributed to parental education, poverty, the quality of the neighborhood, and many other factors to isolate the effects of microparticles compared to these other known influences on crime.
Younan says that her results are particularly worrying, as we know that an adolescent's behavior in puberty is a strong indicator of how they behave, behaving like an adult. Prisoners are more likely to do poorly at school, later become unemployed and more susceptible to substance abuse. This means that early intervention should be a priority.
Exposure to various pollutants can lead to inflammation in the brain
There are many possible mechanisms that could explain the influence of air pollution on our morale.
Lu has shown, for example, that the mere thought of pollution can influence our psychology by its action negative associations.
Of course, researchers were unable to physically expose participants to environmental pollution so they took the next (ethically accepted) step. They showed both American and Indian participants photos of an extremely polluted city and asked them to imagine living there. "We have psychologically induced them to experience the effects of pollution," explains Lu. "… then they asked them to really imagine living in this city and how they feel and how their lives would live in this environment so that they can experience air pollution in a clean environment."
He found the Participant was scared and they became more self-centered – two reactions that could aggravate aggressive and irresponsible behavior. "As a self-defense mechanism, we all know that when we're worried, we're more likely to hit someone in the face than when we're quiet," says Lu. "So if people's anxiety is increased, air pollution can affect behavior."
If we're worried, we're more likely to hit someone in the face than when we're quiet
. The team showed that under the "dirty" conditions, participants cheated more frequently on multiple tasks and overestimated their performance in order to receive rewards.
This research is just beginning, and there may be many reasons for these effects – increased anxiety and self-focus, which Lu describes – including physiological changes in the brain. For example, inhaling polluted air will affect the amount of oxygen you have in your body at any given time, and this in turn may result in less good air getting into your brain. It can also irritate the nose and throat and cause headaches – all of which can lower our concentration.
It is also clear that exposure to various pollutants can cause inflammation in the brain and damage the brain structure and nerve connections. "So what could happen is that these pollutants are damaging the Vorfrontlappen," says Younan. This is the area that is important for the control of our impulses, our executive function and our self-control.
Apart from increasing crime, this could also result in a significant decline in mental health. A March 2019 study even showed that adolescents exposed to toxic, polluted air are at greater risk for psychotic episodes, such as voices or paranoia. Leading researcher Joanne Newbury of King's College London says she can not yet claim that her findings are the cause, but the findings are in line with other studies that suggest an association between air pollution and mental health. "It is a testament to the link between air pollution and physical health problems and the association of dementia with air pollution. If it's bad for the body, it's expected to be bad for the brain, "she says.
The experts say there needs to be greater awareness of the effects of pollution now, as well as the established ones Impact on our health "We need more studies that show the same in other populations and age groups," says Younan.
Fortunately, we have some control over how much pollution we're exposed to each day, we can be proactive and the air quality Monitors indicate on which days it is most dangerous and when it is lowest. "If it is dangerous, I would not suggest running outside or working inside," says Younan.
While many countries are waiting for stricter laws or government interventions to stem pollution, some places have positives I've taken steps. Take California, where regulation has resulted in less pollution and, interestingly enough, fewer crimes. Although promising, Younan emphasizes that we do not yet know if this is coincidence or not. In London, from 8 April 2019, there will be a new "ultra low emissions zone", the stricter emission standards with an additional charge of £ 12.50 ($ 16.30) for the "most types of vehicles" in addition to the existing 11, £ 50 charge. More green buses are also being introduced under the Clean Air for London initiative.
"We are making a pretty good contribution to reducing pollution in many countries, but we should do more," says Roth. "It's not necessarily just a government. But it's you and me too. When we think about what we want to buy, how we get to places, we all have an impact on the environment and we need to be aware of it and make more informed decisions about what we do.  Roth remains confident that rising pollution is something to solve, but that we need to solve. Until then, however, we need to make people aware of the problems.
If we all start to monitor pollution levels ourselves, we may be in the habit of avoiding certain activities, such as outdoor sports, or even commuting on the most polluted days. Our body, our brain and our behavior will benefit.
Melissa Hogenboom is the publisher of BBC Reel. Her film on the same subject can be seen here, she is @melissasuzanneh on Twitter.