{"id":1046,"date":"2026-04-16T13:58:09","date_gmt":"2026-04-16T13:58:09","guid":{"rendered":"https:\/\/flatplanplus.io\/bbc-sciencefocus\/?p=1046"},"modified":"2026-04-16T13:58:09","modified_gmt":"2026-04-16T13:58:09","slug":"an-invisible-smoke-is-spreading-across-us-cities-and-making-people-more-violent","status":"publish","type":"post","link":"https:\/\/flatplanplus.io\/bbc-sciencefocus\/2026\/04\/16\/an-invisible-smoke-is-spreading-across-us-cities-and-making-people-more-violent\/","title":{"rendered":"An invisible smoke is spreading across US cities \u2013 and making people more violent"},"content":{"rendered":"\n
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Health<\/p>\n\n\n\n

An invisible smoke is spreading across US cities \u2013 and making people more violent<\/h1>\n\n\n\n

Wildfires wreck homes and livelihoods. Now, new research suggests their smoke may affect mental health too \u2013 and cause an increase in violent crime<\/p>\n\n\n\n

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By Jheni Osman<\/p>\n\n\n\n

–<\/p>\n<\/div>\n<\/div>\n\n\n\n

\"Seattle
Photo credit: Getty<\/figcaption><\/figure>\n<\/div>\n<\/div>\n\n\n\n

Flames tower over the redwoods. A thick blanket of black smoke spirals upwards, leaving behind a pungent, acrid stench. A fierce wind howls, sucking at the flames. The wall of fire edges closer, slowly eating through the forest.<\/p>\n\n\n\n

Wildfires<\/a> are on the rise around the globe. Ever more frequent<\/a>, severe and longer-lasting fire hotspots are expanding to new territories, as the fingers of climate change reach further around the planet.<\/p>\n\n\n\n

But it\u2019s not just the destructive power of the flames we need to worry about. As the landscape burns, it releases a hazardous mix of pollutants into the atmosphere, including ozone, nitrogen oxide, and ultrafine particles.<\/p>\n\n\n\n

The people living nearby aren\u2019t the only ones choking on the smoke. If the wind is strong enough, toxic wildfire smoke can be detected hundreds of kilometres from the actual flames. You could be in New York and breathe in the smoke from a wildfire raging in California without ever knowing.<\/p>\n\n\n\n

\"Map
Smoke from a 2020 fire in LA was carried by the wind up right across the US. Photo credit: NOAA<\/figcaption><\/figure>\n\n\n\n

This isn\u2019t just hazardous to our physical health. It\u2019s impacting people\u2019s mental wellbeing as well.<\/p>\n\n\n\n

But perhaps the most insidious threat is only now being understood. New research has found that wherever the smoke goes, a rise in crime may not be far behind.<\/p>\n\n\n\n

Smoke, and crime, are on the rise<\/h2>\n\n\n\n

Political scientist Lion Kircheis, from the University of Konstanz, grew up in southern Germany, but often holidayed in Italy, where he experienced wildfires first-hand.<\/p>\n\n\n\n

He remembers the smoke scratching at his throat and making his eyes water, leaving him irritable. Were other people\u2019s moods impacted by the smoke in the air?<\/p>\n\n\n\n

Last year, Kircheis decided to investigate whether there could be a link between wildfires and behaviour, and began pouring over the US city of Seattle.<\/p>\n\n\n\n

\u201cSeattle is a good case study as it has above-average air quality, because fresh air gets blown in from the Pacific. One day there is smoke from a wildfire. The next day the wind direction shifts, and the air is clean again,\u201d says Kircheis.<\/p>\n\n\n\n

This makes it much easier to compare days where smoke is polluting the air to days when the air is clear.<\/p>\n\n\n\n

\"Seattle
Seattle is surrounded by water, which creates breezes that act as a natural ventilator. Photo credit: Getty<\/figcaption><\/figure>\n\n\n\n

\u201cSeattle also has lots of publicly available data from the Environmental Protection Agency [EPA], as well as quality data on traffic, crime and police use of force.\u201d<\/p>\n\n\n\n

Kircheis analysed crime report data from the Seattle Police Department from 2013 to 2023, and identified smoky days caused by wildfires on the basis of satellite data, analyses of wind direction and local monitoring stations.<\/p>\n\n\n\n

What he found surprised him. For all 11 years, assaults were higher on days when nearby wildfires had released smoke and particulate matter into the Seattle air.<\/p>\n\n\n\n

On average<\/a>, when the particulate matter increased by 7.0 \u03bcg\/m3<\/sup>, there were 3.6 per cent more cases of assault on these smoky days.<\/p>\n\n\n\n

\u201cThat\u2019s equivalent to around one additional assault per day in a city the size of Seattle. The statistical increase of 3.6 per cent is not high but, crucially, it is consistent,\u201d says Kircheis.<\/p>\n\n\n\n

\u201cOn those days, when air pollution is up by 7.0 \u03bcg\/m3<\/sup>, it\u2019s not as if the sun gets blocked by a thick haze of smoke or anything \u2013 the air still looks clear.<\/p>\n\n\n\n

\u201cBut what is striking is that even a little bit of smoke in the air has an impact on people.\u201d<\/p>\n\n\n\n

\"A
Near the fire, thick smoke obscures sight. But even traces of smoke can impact how people behave. Photo credit: Getty<\/figcaption><\/figure>\n\n\n\n

Kircheis looked for any other likely causes for the increase in violence, such as more traffic jams or an increase in police response time. But neither of these were the case.<\/p>\n\n\n\n

Interestingly, domestic violence call numbers didn\u2019t rise when wildfire smoke was present. That suggests that outdoor exposure to wildfire smoke was the culprit \u2013 not indoor air pollution.<\/p>\n\n\n\n

And, of course, socio-economic background then comes into play \u2013 although we might think we all breathe the same air, it\u2019s not the case for those who work outdoors or do not have access to filtered indoor air.<\/p>\n\n\n\n

This doesn\u2019t mean the average person will become more violent just because they’re inhaling invisible wildfire smoke. What is more likely is that aggressive conflicts will spill over into violent actions when there is wildfire-induced smoke in the air.<\/p>\n\n\n\n

And it\u2019s not just civilians who are susceptible. Police statistics suggest that officers in Seattle responded with more physical force on those smoky days.<\/p>\n\n\n\n

The findings are supported by another study<\/a> that used crime data from 21 major US cities from 2007 to 2020. This research showed that violent and drug-related crimes were particularly prevalent when wildfire smoke was in the air, with a 0.88 per cent increase in violent offences and 1.35 per cent rise in drug-related crimes.<\/p>\n\n\n\n

Bad air, bad day<\/h2>\n\n\n\n

It\u2019s well established that air pollution is not good for our brains. Numerous studies have found that exposure to air pollution \u2013 whether from wildfires or some other source \u2013 is linked to an increase in adverse mental health.<\/p>\n\n\n\n

One paper<\/a> from the University of Oxford found exposure to air pollutants may lead to depression, anxiety and psychoses. Another study<\/a> showed that people exposed to higher levels of air pollutants around their homes used mental healthcare services more frequently.<\/p>\n\n\n\n

And, poor quality air has been linked to rises in crime. Jesse Burkhardt, an associate professor from Colorado State University (CSU) has been studying the link for years.<\/p>\n\n\n\n

\"Hands
While the study couldn’t point to a direct link, smoky days are definitely linked to a rise in crime. Photo credit: Getty<\/figcaption><\/figure>\n\n\n\n

Back in 2019<\/a>, Burkhardt analysed daily FBI crime data, air pollution maps produced by the CSU atmospheric science department from 2006 to 2013, and wildfire smoke plumes from satellite images created by the National Oceanic and Atmospheric Administration (NOAA) Hazard Mapping System.<\/p>\n\n\n\n

\u201cOur research showed that increased air pollution exposure is associated with higher levels of assaults, which is indicative of elevated aggressive behaviour,\u201d says Burkhardt.<\/p>\n\n\n\n

The researchers ensured external factors weren\u2019t causing the link by using \u2018fixed effects\u2019, for example, only comparing data on a certain weekday in a particular city.<\/p>\n\n\n\n

\u201cIf pollution went up on a Monday and crime went up on that same Monday, that was the correlation we were looking for,\u201d says Burkhardt. \u201cThe most surprising thing about our results was that the correlation showed up in the data \u2013 the link was fairly robust.\u201d<\/p>\n\n\n\n

Something about bad air appears to be driving people towards crime.<\/p>\n\n\n\n

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Read More:<\/h3>\n\n\n\n