How to make future autonomous transportation accessible to everyone

Indiana innovation steers autonomous vehicle design toward inclusiveness for people with disabilities

Business Announcement

PURDUE UNIVERSITY

 

IMAGE: PURDUE UNIVERSITY PROFESSOR BRAD DUERSTOCK LEVERAGES HIS OWN EXPERIENCES AS A WHEELCHAIR USER IN HIS RESEARCH ON IMPROVING ACCESSIBILITY TO TRANSPORTATION. view more 

CREDIT: PURDUE UNIVERSITY PHOTO/JOHN UNDERWOOD

WEST LAFAYETTE, Ind. – When Brad Duerstock was 18, a spinal cord injury paralyzed his arms and legs, requiring him to use what control he had left in his hands to operate a power wheelchair.

Throughout the more than 30 years since, Duerstock has seen smartphones, tablets and other types of technology get developed but not become usable for him or others with disabilities until years later.

“It’s always been a retroactive accommodation,” he said. 

Duerstock, a professor of practice in industrial engineering and biomedical engineering at Purdue University, is working to change that for autonomous vehicles while the technology is still in its early days. The goal is that when these vehicles start to hit the road everywhere, they will be able to accommodate anyone who wants to use them.

“It’s really the wrong way to go to figure out how to adapt technology for a wheelchair user after already developing the technology,” he said. “But if, instead, we consider, ‘Hey, these are all the needs,’ and then create some standards based on the minimum requirements of what the entire population needs, we can design the vehicle around those minimum standards.”

Helping to establish standards on accessibility for autonomous vehicles

Duerstock and Brandon Pitts, a Purdue assistant professor of industrial engineering, have worked together for four years on topics related to technology accessibility and inclusive design and have constantly sought opportunities to contribute their ideas to help shape the future of transportation. 

These ideas are already becoming part of a major national conversation on how to make autonomous transportation more inclusive.

Earlier this week, Duerstock was a panelist for a webinar on accessibility and transportation hosted by Challenge.Gov, a program managed by the U.S. General Services Administration that crowdsources innovative solutions to critical issues through federally sponsored prize competitions.

Duerstock shared how he and Pitts co-led a team to develop a design concept for helping the industry make autonomous vehicles accessible to people with disabilities. Their team’s design concept won first place in a U.S. Department of Transportation competition this summer. The goal of the competition, called the Inclusive Design Challenge, is to spur the innovation needed to ensure that when autonomous transportation becomes widespread, it can accommodate people with any travel-limiting disability or mobility challenge.

The winning design not only took into consideration the transportation challenges that people with disabilities face but also built on years of ideas generated among Duerstock, Pitts and BraunAbility, an Indiana-based company that has been designing and manufacturing vehicle accessibility solutions since 1972. Duerstock is among the first wheelchair users to have provided feedback on new product designs at the recently opened BraunAbility Global Innovation Lab in the Indianapolis area.

“We’ve had the steady benefit of Professor Duerstock’s expertise over the years,” said Phill Bell, senior director of global corporate strategy for BraunAbility. “It’s always good to have users come in and say, ‘I don’t like this interface’ or ‘I can’t see where I’m backing up in my wheelchair.’ As an engineer, Professor Duerstock can help steer us into the direction we should be headed.” 

By the time Duerstock, Pitts and Bell had heard about the Inclusive Design Challenge, they had already identified autonomous vehicles as an opportunity to change the lives of people with disabilities and were working toward design solutions.

“BraunAbility, with Purdue, thinks about accessibility from the get-go, and we can bring those considerations to the original equipment manufacturers while they’re early in their design work,” Bell said.

What an inclusive autonomous vehicle could look like

For the Inclusive Design Challenge, the team built an automated, vehiclelike prototype that demonstrates the features autonomous transportation would need to serve people with a range of disabilities. The researchers call the prototype EASI RIDER, which stands for “Efficient, Accessible and Safe Interaction in a Real Integrated Design Environment for Riders with disabilities.” 

Even though EASI RIDER isn’t meant to be driven (it doesn’t have a motor), the researchers showed that whether a person’s disability is physical or sensory, they can successfully operate the vehicle’s different controls all by themselves. 

EASI RIDER not only has a voice-activated, wheelchair-accessible ramp but also uses sensors to prevent inadvertent deployment of the ramp into obstacles when parked. A mechanism within EASI RIDER helps secure a wheelchair into the safest position during a ride. The prototype can accommodate up to two wheelchair users at once and has reconfigurable seats for riders who don’t use wheelchairs. Cameras and sensors help passengers to better understand their surroundings in the vehicle and allow a remote operator to communicate with them in the case of emergency situations where the passengers might need assistance.

Using their personal mobile phone or tablet, a traveler can control the vehicle’s features such as interior lighting, the horn, headlights and entertainment. A screen inside of the vehicle would help a rider see the operator or access a map of their route if they are hearing-impaired or aren’t able to use their hands to press buttons.

“A lot of the features we included in the vehicle were intended to enable what we call a ‘seamless travel experience,’ which means that interacting with the vehicle is so natural that a person doesn’t know they’re interacting with it,” said Pitts, who conducts research on how older adult populations interact with various autonomous systems.

Pitts’ research influenced the design of EASI RIDER’s features. “Many of the same design solutions tested in my lab that aim to help aging adults better use digital technologies can also be used to support individuals with a range of disabilities,” Pitts said.

The EASI RIDER prototype also incorporated input from people with disabilities, including BraunAbility’s Driving Force, through surveys, interviews and interactive demonstration sessions. EASI RIDER was built using parts and expertise from three other companies in addition to BraunAbility: Local Motors, Schaeffler, and Prehensile Technologies, a startup run by Duerstock and Purdue alumnus Jeffrey Ackerman. Prehensile Technologies specializes in using robotics and power sensor systems for wheelchair users, building on robotic desk and table concepts co-invented by Duerstock and patented through the Purdue Research Foundation Office of Technology Commercialization. Prehensile Technologies is a client of the Purdue Foundry, an entrepreneurship and commercialization hub whose professionals help Purdue innovators create startups.

Even though EASI RIDER’s parts are technology that has already been serving people with disabilities in different settings – the automotive controls that Schaeffler contributed, for example, enable wheelchair users to drive cars – how these parts were integrated together is what makes the design so innovative.

“As we were finishing up the process of building EASI RIDER, I stepped inside of it and felt like I was standing in the future,” Bell said. “I hadn’t seen this sort of integration anywhere. This is the first iteration of what’s coming down the line.”

Thinking ahead on the future of transportation

The EASI RIDER team was awarded $1 million with its Inclusive Design Challenge win. Duerstock and Pitts will be using the prize money to establish a center at Purdue on accessible design for transportation. Through this center, Purdue researchers will engage with industry partners and governmental bodies to keep working toward inclusive vehicle design standards.

“We envision that our work will help build a more equitable transportation future and, in turn, promote a higher quality of life for people at different points along the ability spectrum,” Pitts said.

The team will also continue researching ways to develop technology that is universal for a wide range of disabilities. “Even though I have my own unique perspective, it’s not everyone’s perspective,” Duerstock said. “It takes some depth in understanding of what are everyone’s needs.”

Purdue University researchers and their collaborators developed a realistic demonstration of an accessible design concept that industry could incorporate into its development of autonomous vehicles.

Brad Duerstock and Phill Bell (right) have been collaborating for eight years on how to improve the design of vehicles for people with disabilities

Brandon Pitts sits in the seat of an advanced driving simulator in his lab at Purdue University, where he studies how autonomous vehicles could accommodate older adult travelers who may want to use them in the future.

CREDIT

Purdue University photo/John Underwood

With training, people in mind-controlled wheelchairs can navigate normal, cluttered spaces

Peer-Reviewed Publication

CELL PRESS

 

VIDEO: THIS VIDEO SHOWS A PARTICIPANT OPERATING A MIND-CONTROLLED WHEELCHAIR ACROSS A CLUTTERED ROOM. view more 

CREDIT: LUCA TONIN

A mind-controlled wheelchair can help a paralyzed person gain new mobility by translating users’ thoughts into mechanical commands. On November 18 in the journal iScience, researchers demonstrate that tetraplegic users can operate mind-controlled wheelchairs in a natural, cluttered environment after training for an extended period.

“We show that mutual learning of both the user and the brain-machine interface algorithm are both important for users to successfully operate such wheelchairs,” says José del R. Millán, the study’s corresponding author at The University of Texas at Austin. “Our research highlights a potential pathway for improved clinical translation of non-invasive brain-machine interface technology.”

Millán and his colleagues recruited three tetraplegic people for the longitudinal study. Each of the participants underwent training sessions three times per week for 2 to 5 months. The participants wore a skullcap that detected their brain activities through electroencephalography (EEG), which would be converted to mechanical commands for the wheelchairs via a brain-machine interface device. The participants were asked to control the direction of the wheelchair by thinking about moving their body parts. Specifically, they needed to think about moving both hands to turn left and both feet to turn right.

In the first training session, three participants had similar levels of accuracy—when the device’s responses aligned with users’ thoughts—of around 43% to 55%.  Over the course of training, the brain-machine interface device team saw significant improvement in accuracy in participant 1, who reached an accuracy of over 95% by the end of his training. The team also observed an increase in accuracy in participant 3 to 98% halfway through his training before the team updated his device with a new algorithm. 

The improvement seen in participants 1 and 3 is correlated with improvement in feature discriminancy, which is the algorithm’s ability to discriminate the brain activity pattern encoded for “go left” thoughts from that for “go right.” The team found that the better feature discrimnancy is not only a result of machine learning of the device but also learning in the brain of the participants. The EEG of participants 1 and 3 showed clear shifts in brainwave patterns as they improved accuracy in mind-controlling the device.

“We see from the EEG results that the subject has consolidated a skill of modulating different parts of their brains to generate a pattern for ‘go left’ and a different pattern for ‘go right,’” Millán says. “We believe there is a cortical reorganization that happened as a result of the participants’ learning process.”

Compared with participants 1 and 3, participant 2 had no significant changes in brain activity patterns throughout the training. His accuracy increased only slightly during the first few sessions, which remained stable for the rest of the training period. It suggests machine learning alone is insufficient for successfully maneuvering such a mind-controlled device, Millán says

By the end of the training, all participants were asked to drive their wheelchairs across a cluttered hospital room. They had to go around obstacles such as a room divider and hospital beds, which are set up to simulate the real-world environment. Both participants 1 and 3 finished the task while participant 2 failed to complete it.

 “It seems that for someone to acquire good brain-machine interface control that allows them to perform relatively complex daily activity like driving the wheelchair in a natural environment, it requires some neuroplastic reorganization in our cortex,” Millán says.

The study also emphasized the role of long-term training in users. Although participant 1 performed exceptionally at the end, he struggled in the first few training sessions as well, Millán says. The longitudinal study is one of the first to evaluate the clinical translation of non-invasive brain-machine interface technology in tetraplegic people.

Next, the team wants to figure out why participant 2 didn’t experience the learning effect. They hope to conduct a more detailed analysis of all participants’ brain signals to understand their differences and possible interventions for people struggling with the learning process in the future.

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This work was partially supported by the Italian Minister for Education and by the Department of Information Engineering of the University of Padova. 

iScience, Tonin and Perdikis et al.: “Learning to control a BMI-driven wheelchair for people with severe tetraplegia.” https://www.cell.com/iscience/fulltext/S2589-0042(22)01690-X 

iScience (@iScience_CP) is an open access journal from Cell Press that provides a platform for original research and interdisciplinary thinking in the life, physical, and earth sciences. The primary criterion for publication in iScience is a significant contribution to a relevant field combined with robust results and underlying methodology. Visit http://www.cell.com/iscience. To receive Cell Press media alerts, contact press@cell.com.

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JOURNAL

iScience

DOI

10.1016/j.isci.2022.105418 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Learning to control a BMI-driven wheelchair for people with severe tetraplegia

ARTICLE PUBLICATION DATE

18-Nov-2022

Corporate pledges to recycle or reduce plastics aren't translating into less plastic use

Peer-Reviewed Publication

CELL PRESS

 

IMAGE: THIS GRAPHICAL ABSTRACT DEPICTS THE FINDINGS OF DIANA ET AL., WHO ANALYZED VOLUNTARY COMMITMENTS TARGETING PLASTIC POLLUTION MADE BY 974 COMPANIES GLOBALLY BETWEEN 2015 AND 2020. view more 

CREDIT: DIANA ET AL./ONE EARTH

Plastic pollution is overwhelming landfills, littering Earth’s coastlines, and affecting the health of animals, including humans, while also contributing to environmental degradation and climate change. As public expectations for corporate responsibility grow and an increasing number of businesses pledge to reduce plastic use, researchers publishing in the journal One Earth on November 18 detail how the world’s largest and most powerful companies’ focus on recycling rather than virgin plastic reduction makes their commitments less meaningful.

The study focused on the top 300 Fortune 500 companies and found that 72% had made a commitment to reducing plastic pollution. “Most of the commitments emphasize plastic recycling and commonly target general plastics,” write the authors, led by Zoie Taylor Diana, an environmental researcher at the Duke University Marine Laboratory. “They are important, but partial, solutions if we are to comprehensively address the plastic pollution problem.”

“Between 1950 and 2017, plastics production increased 174-fold and is forecast to double again by 2040,” the authors write. “As of 2015, an estimated 79% of global plastic waste was in landfills or ended up in the natural environment, 12% was incinerated, and 9% was recycled. Plastics in the environment have negative repercussions at all levels of biological organization.”

The paper highlights the companies’ overwhelming focus on changing their consumption and production patterns, often by including more recycled content in their products and “lightweighting”—the practice of marginally reducing the volume of plastic used to package a particular product.

“From our literature review, we found that multiple companies, such as the Coca-Cola Company and Walmart, are producing lighter and smaller plastic products (e.g., bottles and bags),” write the authors. “This ‘lightweighting’ of plastic is considered an insufficient response because companies may reinvest this savings into markets that involve new plastic products and/or increase the total mass of plastic produced.” Because the number of plastic products increases each year, the use of this practice does not result in a net reduction of plastic.

Going forward, the authors say that the scientific community should continue to monitor the plastic practices of major companies and the effects that plastics are having on the planet. “Scientists (including natural, life, and social scientists) have an important role in monitoring and defining environmental issues, which may aid in holding companies accountable.”

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This study was funded by the Pew Charitable Trusts. The authors declare no competing interests.

One Earth, Diana et al. “Voluntary commitments made by the world’s largest companies focus on general plastic and recycling over other actions to address the plastics crisis” https://www.cell.com/one-earth/fulltext/S2590-3322(22)00534-6 

One Earth (@OneEarth_CP), published by Cell Press, is a monthly journal that features papers from the fields of natural, social, and applied sciences. One Earth is the home for high-quality research that seeks to understand and address today’s environmental Grand Challenges, publishing across the spectrum of environmental change and sustainability science. A sister journal to Cell, Chem, and Joule, One Earth aspires to break down barriers between disciplines and stimulate the cross-pollination of ideas with a platform that unites communities, fosters dialogue, and encourages transformative research. Visit http://www.cell.com/one-earth. To receive Cell Press media alerts, contact press@cell.com.

For the latest sustainability research and ideas from Cell Press, follow @CellPressSust on Twitter.

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JOURNAL

One Earth

DOI

10.1016/j.oneear.2022.10.008 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Voluntary commitments made by the world’s largest companies focus on general plastic and recycling over other actions to address the plastics crisis

ARTICLE PUBLICATION DATE

18-Nov-2022

New insights into energy loss open doors for one up-and-coming solar tech

Peer-Reviewed Publication

PRINCETON UNIVERSITY, ENGINEERING SCHOOL

 

IMAGE: HEADSHOT OF BARRY RAND, PAPER CO-AUTHOR view more 

CREDIT: ANDLINGER CENTER FOR ENERGY AND THE ENVIRONMENT

Organic solar cells are an emerging technology with a lot of promise. Unlike the ubiquitous silicon solar panel, they have the potential to be lightweight, flexible, and present a variety of colors, making them particularly attractive for urban or façade applications. However, continued advancements in device performance have been sluggish as researchers work to understand the fundamental processes underlying how organic solar cells operate.

Now, engineers at Princeton University and King Abdullah University of Science and Technology have described a new way to express energy loss in organic solar cells and have extended that description to make recommendations for engineering the best devices. This breakthrough could reimagine the conventional approach to constructing organic solar cells. Their work was published on November 18 in Joule. 

“There was a way that energy loss in organic solar cells was traditionally described and defined. And it turns out that that description was not wholly correct,” said Barry Rand, co-author of the study and associate professor of electrical and computer engineering and the Andlinger Center for Energy and the Environment.

Rand pointed out that the traditional method for describing energy loss did not account for the presence of disorder in an organic solar cell. One type of disorder, dynamic disorder, is caused by the erratic movement of molecules at the micro level, leading to energy loss that is practically unavoidable at most temperatures. The other type, structural or static disorder, is a product of the intrinsic structures of the various materials used in an organic solar cell, as well as their arrangement inside a device.

Past research on organic solar cells that did not account for disorder in energy loss calculations yielded values around 0.6 electron volts, regardless of the device’s materials. But when Rand and his team incorporated disorder into the way they calculated energy loss and tested various devices, they found that the level of disorder played an important role in determining the overall energy loss of an organic solar cell. 

“As the disorder of a solar cell increases, we see our non-radiative energy loss component — the component that we have control over — grows rapidly,” Rand said. “The non-radiative energy loss grows with the square of the disorder component.”

After demonstrating that increasing disorder causes energy loss to sharply increase in devices, the researchers were able to make recommendations for materials that minimize disorder and therefore lead to more efficient devices. Since scientists can choose the materials they use as well as how to arrange them in an organic solar cell, they have some control over the level of structural disorder in a given device.

When engineering an organic solar cell, researchers can focus on creating a homogenous mixture of materials, in which the parts of a film are either all crystalline or all amorphous, or a heterogeneous mixture, in which some parts of a film are crystalline and other parts are amorphous.

Through their work, Rand’s team demonstrated that when it comes to building organic solar cells, homogeneous mixtures reign supreme. For better-performing organic solar cells, Rand said that scientists should use either highly crystalline or highly amorphous materials and avoid mixing the two within a device.

“If you have anything in between, some heterogeneity in which parts of a film are slightly crystalline and some parts are amorphous, that's when you lose the most energy,” Rand said.

This finding breaks with convention, as researchers previously believed that some level of heterogeneity in solar cell mixtures was beneficial for overall performance. But because Rand’s team found that heterogeneous device mixtures had high levels of disorder and lost significant amounts of energy, he said that their discovery could provide new focus for researchers as they pursue more efficient organic solar cells.

“Heterogeneity has often been the focal point of devices. Some level of crystallinity was thought to be beneficial. But it turns out that that’s not what we saw,” said Rand. He pointed out that many of the top-performing organic solar cells today are composed of highly amorphous films, and suggested that with existing technologies, completely amorphous mixtures are more pragmatic than completely crystalline ones.

Although his team’s research primarily sought to understand the science behind organic solar cells, Rand is hopeful that others can use their work to build more efficient devices and ultimately reach new performance benchmarks for this promising solar technology.

“This discovery is another aspect of organic solar cells that we can add to what we already know, which will help us improve their efficiency going forward,” Rand said.

The article, “Quantifying the Effect of Energetic Disorder on Organic Solar Cell Energy Loss,” was published in Joule on November 18. Besides Rand, authors include Saeed-Uz-Zaman Khan, a former graduate student in electrical and computer engineering who is now at ASML; and Manting Gui of Princeton University; and Jules Bertrandie, Anirudh Sharma, Wejdan Alsufyani, Julien F. Gorenflot, Frédéric Laquai, and Derya Baran of King Abdullah University of Science and Technology. Support for the research was provided by the U.S. Department of Energy, Office of Basic Energy Sciences and King Abdullah University of Science and Technology Office of Sponsored Research.

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JOURNAL

Joule

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Quantifying the Effect of Energetic Disorder on Organic Solar Cell Energy Loss

ARTICLE PUBLICATION DATE

18-Nov-2022

Association of Recreational Cannabis Legalization With Alcohol Use Among Adults in the US, 2010 to 2019

Vandana Macha¹; Rahi Abouk, PhD²; Coleman Drake, PhD^1,3

Author Affiliations Article Information

JAMA Health Forum. 2022;3(11):e224069. doi:10.1001/jamahealthforum.2022.4069

 Original Investigation

November 18, 2022

Key Points

Question  How do recreational cannabis laws affect alcohol use among adults in the US?

Findings  In this cross-sectional study with a difference-in-differences analysis of 4.2 million adults in all 50 states from 2010 to 2019, recreational cannabis laws were associated with a 0.9 percentage point increase in any alcohol use among the population overall but not in binge or heavy drinking. Results were primarily determined by younger adults (18-24 years) and men.

Meaning  These findings suggest that increased alcohol use may be an unintended consequence of recreational cannabis laws.

Abstract

Importance  In the US, cannabis use has nearly doubled during the past decade, in part because states have implemented recreational cannabis laws (RCLs). However, it is unclear how legalization of adult-use cannabis may affect alcohol consumption.

Objective  To estimate the association between implementation of state RCLs and alcohol use among adults in the US.

Design, Settings, and Participants  This was a cross-sectional study of 4.2 million individuals who responded to the Behavioral Risk Factor Surveillance System in 2010 to 2019. A difference-in-differences approach with demographic and policy controls was used to estimate the association between RCLs and alcohol use, overall and by age, sex, race and ethnicity, and educational level. Data analyses were performed from June 2021 to March 2022.

Exposures  States with RCLs, as reported by the RAND−University of Southern California Schaeffer Opioid Policy Tools and Information Center.

Main Outcomes and Measures  Past-month alcohol use, binge drinking, and heavy drinking.

Results  Of 4.2 million respondents (median age group, 50-64 years; 2 476 984 [51.7%] women; 2 978 467 [58.3%] non-Hispanic White individuals) in 2010 through 2019, 321 921 individuals lived in state-years with recreational cannabis laws. Recreational cannabis laws were associated with a 0.9 percentage point (95% CI, 0.1-1.7; P = .02) increase in any alcohol drinking but were not significantly associated with binge or heavy drinking. Increases in any alcohol use were primarily among younger adults (18-24 years) and men, as well as among non-Hispanic White respondents and those without any college education. A 1.4 percentage point increase (95% CI, 0.4-2.3; P = .006) in binge drinking was also observed among men, although this association diminished over time.

Conclusions and Relevance  This cross-sectional study and difference-in-differences analysis found that recreational cannabis laws in the US may be associated with increased alcohol use, primarily among younger adults and men.

Introduction

Alcohol and cannabis are the first and third most-used substances in the US.¹ Past-month adult cannabis use has nearly doubled during the past decade, increasing from 6.9% in 2010 to 11.9% in 2019.² During each year from 2011 to 2015, there were approximately 95 000 alcohol-attributable deaths in the US.^3,4

Cannabis use may contribute to poor health outcomes in adults, both by itself and when used with alcohol. By itself, cannabis use increases the risk of cannabis use disorder, nausea, and hyperemesis, and may increase the risk of some mental health conditions.⁵ Co-use of cannabis and alcohol may increase the probability of unsafe driving, beyond the risk associated with consuming either substance alone.^6,7 In addition, co-use also has been associated with increased impulsivity, which may give rise to potentially dangerous behaviors.⁸ In addition, simultaneous use of cannabis and alcohol has been associated with increased alcohol use frequency and quantity and an increased risk of drunk driving.^5,8-11

Cannabis use has increased alongside widespread liberalization of state cannabis policy.^11,12 As of August 2022, 38 states had implemented medical cannabis laws, 19 of which also legalized recreational cannabis for adult use.¹² Recreational cannabis also is legal in the District of Columbia. These recreational cannabis laws (RCLs) have made cannabis accessible to approximately half of adults in the US.^13,14 They have resulted in a 25% increase in cannabis use by adults.¹⁵ Although previous studies indicate the percentage increases in cannabis use in response to RCLs have been as large or larger among older adults compared with younger ones, absolute increases in cannabis use have been larger among younger adults.^15,16 Part of the rationale for these policies is that cannabis is used to treat long-term health conditions, including chronic pain, glaucoma, epilepsy, and anxiety.¹⁷ There is some evidence that cannabis may be a substitute for opioids in the treatment of chronic pain.^18-20

Previous studies investigating the relationship between cannabis and alcohol use have found mixed evidence.^21-24 The findings of 2 studies that used repeated cross-sectional data on college students suggest that alcohol and cannabis are economic complements—that demand for one substance increases along with the other.^21,22 However, the results of a more recent study that used a regression discontinuity design suggest that cannabis and alcohol are substitutes—that demand forone substance decreases as demand for the other increases. Specifically, this study found an increase in alcohol consumption and a decline in cannabis use at the legal drinking age of 21 years.²³ However, another study using the same methods with data from the 1997 National Longitudinal Survey of Youth found no relationship between cannabis and alcohol.²⁴

The association between cannabis policies and adult alcohol use also are unclear.²⁵ Two studies have found that medical cannabis laws reduced alcohol use,^26,27 suggesting that cannabis and alcohol are substitutes. However, 2 other studies found that medical laws increased alcohol use, indicating that the 2 substances were economic complements.^16,28 In particular, little is known about how RCLs affect alcohol use. A recent study found that RCLs increased alcohol use¹⁶; another study found an increase in co-use of cannabis and alcohol and a decline in the use of alcohol alone.²⁹ Both studies used data from the National Survey on Drug Use and Health, which has a sample size of approximately 1-sixth of the size of another publicly available data source, the Behavioral Risk Factor Surveillance System (BRFSS).^30,31 With 1 exception,¹⁶ these studies also did not examine the robustness of their findings to bias from staggered implementation, which may significantly bias difference-in-differences (DiD) study designs.³²

We examined the association between RCLs and alcohol use among adults in the US from 2010 through 2019 using survey data of more than 4.2 million respondents. During the study period, 10 states and the District of Columbia legalized adult-use cannabis. We also evaluated the heterogeneous association of RCLs with alcohol use by age, sex, race and ethnicity, and education level.

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Association of National Football League Fan Attendance With County-Level COVID-19 Incidence in the 2020-2021 Season

Justin Kurland, PhD¹; Wanda E. Leal, PhD²; Erin M. Sorrell, PhD^3,4; et alNicole Leeper Piquero, PhD⁵

Author Affiliations Article Information

JAMA Netw Open. 2022;5(11):e2240132. doi:10.1001/jamanetworkopen.2022.40132

Original Investigation 

Public Health

November 18, 2022

editorial comment ico

Key Points

Question  Was fan attendance at National Football League (NFL) games during the 2020-2021 season associated with subsequent spikes in COVID-19 cases in-county and in contiguous counties?

Findings  In this cross-sectional study of NFL games attended by a total 1.3 million fans, the presence of large numbers of fans at NFL games was associated with increases in the incidence of COVID-19 cases both in the counties in which these venues were located and contiguous counties. Specifically, NFL games that had 20 000 fans in attendance had 2.23 times the rate of spikes in COVID-19, but NFL games with fewer than 5000 fans in attendance did not generate any spikes.

Meaning  This analysis suggests that in-person attended games during the NFL’s 2020 season were associated with subsequent spikes in COVID-19 cases, and that the spikes were most prominent when attendance was over 20 000 persons.

Abstract

Importance  The 2020-2021 National Football League (NFL) season had some games with fans and others without. Thus, the exposed group (ie, games with fans) and the unexposed group (games without fans) could be examined to better understand the association between fan attendance and local incidence of COVID-19.

Objective  To assess whether NFL football games with varying degrees of in-person attendance were associated with increased COVID-19 cases in the counties where the games were held, as well as in contiguous counties, compared with games without in-person attendance for 7-, 14-, and 21-day follow-ups.

Design, Setting, and Participants  This cross-sectional study used data for all 32 NFL teams across the entirety of the 2020-2021 season. Separate daily time-series of COVID-19 total cases and case rates were generated using 7-, 14-, and 21-day simple moving averages for every team and were plotted against the actuals to detect potential spikes (outliers) in incidence levels following games for the county in which games took place, contiguous counties, and a combination. Outliers flagged in the period following games were recorded. Poisson exact tests were evaluated for differences in spike incidence as well across games with different rates of attendance. The data were analyzed between February 2021 and March 2021.

Exposures  Games with fan attendance vs games with no fan attendance, as well as the number of fans in attendance for games with fans.

Main Outcomes and Measures  The main outcome was estimation of COVID-19 cases and rates at the county and contiguous county level at 7-, 14-, and 21-day intervals for in-person attended games and non–fan attended games, which was further investigated by stratifying by the number of persons in fan-attended games.

Results  This included a total of 269 NFL game dates. Of these games, 117 were assigned to an exposed group (fans attended), and the remaining 152 games comprised the unexposed group (unattended). Fan attendance ranged from 748 to 31 700 persons. Fan attendance was associated with episodic spikes in COVID-19 cases and rates in the 14-day window for the in-county (cases: rate ratio [RR], 1.36; 95% CI, 1.00-1.87), contiguous counties (cases: RR, 1.31; 95% CI, 1.00-1.72; rates: RR, 1.41; 95% CI, 1.13-1.76), and pooled counties groups (cases: RR, 1.34; 95% CI, 1.01-1.79; rates: RR, 1.72; 95% CI, 1.29-2.28) as well as for the 21-day window in-county (cases: RR, 1.49; 95% CI, 1.21-1.83; rates: RR, 1.50; 95% CI, 1.26-1.78), in contiguous counties(cases: RR, 1.37; 95% CI, 1.14-1.65; rates: RR, 1.45; 95% CI, 1.24-1.71), and pooled counties groups (cases: RR, 1.41; 95% CI, 1.11-1.79; rates: RR, 1.70; 95% CI, 1.35-2.15). Games with fewer than 5000 fans were not associated with any spikes, but in counties where teams had 20 000 fans in attendance, there were 2.23 times the rate of spikes in COVID-19 (95% CI, 1.53 to ∞).

Conclusions and Relevance  In this cross-sectional study of the presence of fans at NFL home games during the 2020-2021 season, results indicated that fan attendance was associated with increased levels of COVID-19 in the counties in which the venues are nested within, as well as in surrounding counties. The spikes in COVID-19 for crowds of over 20 000 people suggest that large events should be handled with extreme caution during public health event(s) where vaccines, on-site testing, and various countermeasures are not readily available to the public.

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