青奥会前后南京PM2.5重金属污染水平与健康风险评估

人类活动对大气环境的影响已成为人们关注的焦点.于青年奥林匹克运动会(青奥会,Youth Olympic Games)召开前后(2014年4~9月)动态监测南京大气中PM_(2.5)及其6种重金属质量浓度和污染特征,并分析其健康风险.结果表明,观测期间PM_(2.5)质量浓度变化范围为26.39~80.31μg·m~(-3),青奥会前的4、5和7月大气中PM_(2.5)质量浓度均达到国家空气质量二级标准(24 h质量浓度限值75μg·m~(-3)),青奥会期间达到国家空气质量一级标准(24 h质量浓度限值35μg·m~(-3)).青奥会结束后,空气污染出现反弹,大气PM_(2.5)质量浓度平均值为76.14μg·m~(-3).观测期间大气PM_(2.5)中重金属离子质量浓度的变化特征并不一致,主成分分析表明,污染物源排放是影响PM_(2.5)重金属离子质量浓度变化最重要因素.青奥会期间PM_(2.5)及重金属离子质量浓度均降至观测期间最低值,这与召开青奥会所采取的一系列政策干预减排措施发挥作用有关.PM_(2.5)中Cd、Cu、Ni、Pb通过呼吸和皮肤暴露的健康风险值均在可接受水平范围内,而Cr存在较大的致癌风险;Mn通过呼吸暴露对成年男性造成较大的非致癌风险;同时PM_(2.5)中6种重金属通过皮肤暴露对儿童也造成较大非致癌风险.     

Predicting Offenses and Crashes from Young Drivers' Offense and Crash Histories

Previous research has indicated that offenses are better predictors of subsequent crashes than crashes themselves. We examined this hypothesis for 13,800 young beginning drivers in Michigan for up to nine years during the initial years of driving. Our analyses indicated that previous-year offenses are better predictors of both subsequent-year offenses and crashes than either previous-year crashes or at-fault crashes. This finding also held for the apparently higher-risk subset of subsequent-year serious offenses and at-fault crashes. Although there were no gender differences in the predictive power of crashes, it was found that the predictive power of previous offenses to subsequent serious offenses was significantly stronger for women than for men. The predictive power of incidents appeared to increase somewhat with increasing driving experience, suggesting that early incidents may be more attributable to inexperience, a characteristic of all beginning drivers, while later incidents may be more attributable to individual differences.     

Sport participation and injury rates in high school students: A Canadian survey of 2029 adolescents

Introduction: The objective of this study is to examine sport and recreational (S&R) activity participation and injury rates (IR) in high school students (ages 14–19). Methods: High school students (N = 24 schools, n = 2,029; 958 male, 1,048 female, 23 identified ‘other’ or missing; ages 14–19) in Alberta completed a web-based survey during class (October 2018–March 2019). Students identified their top three sports for participation in the past year. Primary outcome measures included IR for (a) any S&R-related injury, (b) most serious S&R-related injury resulting in medical attention, and (c) most serious injury resulting in restriction from S&R for at least one day. Results: In total, 1763/2029 (86.89%) respondents [861/958 (89.87%) male, 886/1048 (84.54%) female, 16/23 (69.57%) identifying as ‘other’ or missing] participated in an S&R activity in the past year. Top sports for male participation were basketball (33.08%; 95% CI 27.67–39.00), ice hockey (20.46%; 95% CI 14.87–27.47), and soccer (19.42%; 95% CI 15.67–23.80). Top sports for female participation were dance (22.52%; 95% CI 17.98–27.82), basketball (18.32%; 95% CI 14.32–23.14), and badminton (17.84%; 95% CI 13.35–23.43). Of the 1,971 students completing the S&R injury question, 889 reported at least one injury during the past year [(IR = 45.10 injuries/100 students/year (95% CI 39.72–50.61)]. The medical attention IR was 29.09 injuries/100 students/year (95% CI 24.49–34.17) and time loss IR was 36.00 injuries/100 students/year (95% CI 30.47–41.93). Conclusions: High school student S&R IRs are high with 29% of adolescents reporting at least one medical attention injury within the past year. Injury prevention strategies targeting youth are necessary. Practical Application: Participation in S&R activities has multiple physical, psychological, and health benefits for adolescents, but some S&R activities also have greater risks of injury. This study informs the next sports to target for implementation of optimal prospective surveillance and injury prevention strategies among high school aged students.     

A gateway to nature: Teenagers' narratives on smoking marijuana outdoors

Increasingly, many youth are disconnected from the natural world; rather, they inhabit a technological world. Although experiences in nature have long been a source of fascination, little is known about how youth independently access and make sense of nature. We focus on the experiences of youth who chose to use marijuana in nature. A substance such as marijuana is often viewed as a “gateway” leading to “harder” drug use; rarely do we consider how marijuana might be a gateway to positive experiences. Narrative analysis was used to explore how young people, aged 14–18, describe their marijuana use in nature, an important aspect of the culture and context of marijuana use. Youth's constructions of nature are revealed in four narratives in which they situate themselves: freedom in nature, the pleasure of leisure, in awe of the natural world and making meaning of the world. One subnarrative, flowing through space, was also uncovered. The findings point to the importance of these nature experiences for youth who expressed how they were able to be in nature in new ways. Participants articulated their yearning for and ability to establish a connection within their natural world.     

Persistence of Violation and Crash Behavior Over Time

This analysis examines the ability of previous offenses to predict future high-risk offenses, and similarly, the ability of crashes to predict future high-risk crashes, using the complete driver history data (up to 9 years) for a set of young Michigan subjects. As expected, those with previous ticketed offenses or reported crashes are at greater risk for future offenses or crashes; with a previous-year serious offense doubling the odds of serious offenses during the subsequent year, and a previous-year at-fault crash increasing the odds of subsequent-year at-fault crashes by nearly 50%. There is modest evidence that serious offenses and at-fault crashes may better predict subsequent behavior in females and in more experienced drivers. This latter finding is also evidenced by the fact that records of these young drivers are less predictive of subsequent driving history than is true for records of all drivers in general found in other studies. This suggests that, in the early stages of driving, offenses and crashes are, at least in part, attributable to inexperience, and hence, characteristic of all beginning drivers.