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African-American young men who have sex with men and transgender persons are at elevated risk for HIV infection. House and Ball communities, networks of mostly African-American gay, bisexual, and transgender individuals who compete in modeling and dance, represent a prime venue for HIV prevention with these difficult-to-reach populations; however, little research exists on effective approaches to HIV prevention within these communities. Using a mixed-methods approach, the present study sought to document participation in HIV prevention activities of a sample from the Los Angeles House and Ball communities (n = 263) in order to inform future service development. While 80% of participants were tested for HIV within the past 6 months, only 26% report HIV prevention program attendance. House leaders recommend a holistic approach to HIV prevention, one that incorporates attention to social problems beyond HIV, including poverty, housing difficulties, and lack of job training.

A growing body of research has investigated the effectiveness of abstinence-only sexual education. There remains a dearth of research on the relevant sexual health information available to young men who have sex with men (YMSM). Drawing on a mixed-methods study with 526 YMSM, this study explores how and where YMSM receive relevant information on sexual health/behavior. Findings indicate that information related to gay men's sexuality is not readily available from family, friends, or schools. At initiation of anal intercourse, respondents generally had limited information about HIV and sexually transmitted infections (STIs). In some cases, this resulted in the perception that activities such as unprotected sex were "low risk." Many mentioned they first learned about anal sex during their sexual debut, describing painful and/or unpleasant experiences. Some relied on older/more experienced partners, the Internet, and pornography for information. Findings are discussed in relation to how providers can help YMSM build solid foundations of sexual education to protect them from STI and HIV infection. (Contains 2 tables and 1 note.)

Young men who have sex with men (MSM) in urban areas of the United States continue to be vulnerable to HIV infection. Qualitative data collected with participants in a community level HIV intervention in West Hollywood and Orange County, California, suggest that space--both actual physical space and the concept of having space--should be an integral part of an HIV prevention intervention for young MSM. Having such spaces appears to contribute to youth sense of empowerment and efficacy and foster community building, all important components of an effective HIV prevention. Data were drawn from a qualitative research sample of 73. Through narratives, young men describe specific characteristics of the space necessary for effective HIV intervention, including mentoring and supportive staff, tolerant and like-minded peers, information exchange, opportunities for strengthening self-esteem, and a sense of collaborative community invested in social change.

This study describes the perceived influence of group-level HIV interventions on persons living with HIV in Los Angeles, California. Funded by the Centers for Disease Control and Prevention and developed by a broad range of community organizations, group-level interventions ranged from small skills-building workshops to large educational forums and to intensive weekend gatherings. Recognizing the relationship between psychosocial factors and HIV-related risk taking, these interventions were designed not only to provide HIV prevention education and develop risk reduction skills but also to bring people together to facilitate the formation of supportive relationships. The formative data presented here are based on 35 qualitative interviews conducted with a sample of intervention participants. Interviews highlight the experiential opportunities that group interventions offer with respect to HIV knowledge, social support, HIV disclosure skills, and HIV risk reductions. Participants talked highly of their experiences in group-level interventions, suggesting that they should be considered an important prevention strategy for people living with HIV.

The effects of atmospheric black carbon (BC) on climate and public health have been well established, but large uncertainties remain regarding the extent of the impacts of BC at different temporal and spatial scales. These uncertainties are largely due to the heterogeneous nature of BC in terms of its spatiotemporal distribution, mixing state, and coating composition. Here, we seek to further understand the size and mixing state of BC emitted from various sources and aged over different timescales using field measurements in the Los Angeles region. We measured refractory black carbon (rBC) with a single-particle soot photometer (SP2) on Catalina Island, California (∼70 km southwest of downtown Los Angeles) during three different time periods. During the first campaign (September 2017), westerly winds were dominant and measured air masses were representative of well-aged background over the Pacific Ocean. In the second and third campaigns (December 2017 and November 2018, respectively), atypical Santa Ana wind conditions allowed us to measure biomass burning rBC (BC bb) from air masses dominated by large biomass burning events in California and fossil fuel rBC (BC ff) from the Los Angeles Basin. We observed that the emissions source type heavily influenced both the size distribution of the rBC cores and the rBC mixing state. BC bb had thicker coatings and larger core diameters than BB ff. We observed a mean coating thickness (CT BC) of ∼40 –70 nm and a count mean diameter (CMD) of ∼120 nm for BC bb. For BC ff , we observed a CT BC of ∼5 –15 nm and a CMD of ∼100 nm. Our observations also provided evidence that aging led to an increased CT BC for both BC bb and BC ff. Aging timescales < ∼1 d were insufficient to thickly coat freshly emitted BC ff. However, CT BC for aged BC ff within aged background plumes was ∼35 nm thicker than CT BC for fresh BC ff. Likewise, we found that CT BC for aged BC bb was ∼18 nm thicker than CT BC for fresh BC bb. The results presented in this study highlight the wide variability in the BC mixing state and provide additional evidence that the emissions source type and aging influence rBC microphysical properties. [ABSTRACT FROM AUTHOR]

Objectives. We investigated the roles of House membership and the influence of social and sexual network members on the sexual risk behavior of men in the Los Angeles House and Ball community. Methods. From February 2009 to January 2010, male participants (n = 233) completed interviewer-assisted surveys during a House meeting or Ball event. We used logistic regression to model the effects of sexual network size, influence of sexual network members, House membership status, and their interactions on high-risk sex. Results. Significant predictors of high-risk sex included number of sexual partners in the nominated social network, multiethnicity, and previous diagnosis of sexually transmitted infection. House membership was protective against high-risk sex. Additionally, a 3-way interaction emerged between number of sexual partners in the network, influence, and network members' House membership. Conclusions. Future research should assess network members' attitudes and behavior in detail to provide a greater understanding of the dynamics of social influence and to identify additional avenues for intervention. [ABSTRACT FROM AUTHOR]

African American young men who have sex with men (AAYMSM) represent the largest proportion of new HIV infections among MSM. While evidence-based interventions are lacking, all too often HIV interventions are implemented in a community without thoroughly understanding its needs, risks and assets. AAYMSM are not homogenous; subgroups exist that may require different approaches to be effective. The House and Ball communities represent one such subgroup. A community-engaged, mixed-methods approach was used. Participant observations, qualitative interviews ( N = 26), and a survey at House/Ball events ( N = 252) were completed. Survey data broadly describe the community. For example: 69 % of survey respondents identify as gay; 25 % as bisexual; 13 % reported recent use of ecstasy and 11 % recently participated in sex exchange. The depth of qualitative data is key for intervention development. For example, while the survey provides broad descriptions of respondents' involvement in the House and Ball communities, leaders provided in-depth descriptions of the structure of the House and Ball scene-something vital to the development of HIV prevention programs within these communities. This kind of rigorous study is recommended prior to implementing an intervention. Findings are discussed in relation to leveraging the communities' supportive aspects to design culturally relevant HIV prevention programs. [ABSTRACT FROM AUTHOR]

This article describes a community-engaged study with the Los Angeles House and Ball scene in which the perspectives of the leaders of these communities are captured to better understand how the House and Ball communities may protect or increase its members' risks for HIV infection. Data were collected through in-depth interviews with House parents (N = 26). This study identified key features of both support (e.g., family and support, acceptance, and validation and recognition) and risk (e.g., members' struggles to maintain status in the Ballroom scene, sex work, substance use, danger of becoming too involved in the Ball community, and perception and stigma of the Ballroom scene within the larger gay community) within these communities. Findings are discussed in relation to framing how to leverage the supportive aspects of the House and Ball communities to design relevant HIV-prevention interventions. [ABSTRACT FROM PUBLISHER]

The article presents a study which examined the association of discrimination, violence, drug abuse among a cohort of young men who have sex with men (YMSM) from Los Angeles, California. A venue-based, stratified probability sampling design which utilized audio computer-assisted interview (ACAI) in both English and Spanish, was used to assess childhood hardships, violence, discrimination, and drug use is discussed. Analysis showed that financial hardships, physical violence from intimate partners, and homophobia increases the risk for drug use. It also indicated that racial/ethnic YMSM were at increased risk for discrimination and violence leading them to resort to drugs.

Qualitative data can be a powerful tool in developing interventions for substance use and other HIV-risk behaviors. Mixed methods design offers researchers the ability to obtain data that provides both breadth and depth to their research questions. However, the integration of qualitative data in mixed methods research has been limited. This paper describes the qualitative study design of the Healthy Young Men's Study, a longitudinal mixed method study with an ethnically diverse cohort of young men who have sex with men (YMSM) ( N = 526) in Los Angeles. Integral to this discussion is how a mixed methods study can address common challenges such as sampling, representation and integration of both datasets. [ABSTRACT FROM AUTHOR]

Abstract: Average particle number concentrations and size distributions from ∼61,000 light-duty (LD) vehicles and ∼2500 medium-duty (MD) and heavy-duty (HD) trucks were measured during the summer of 2006 in a San Francisco Bay area traffic tunnel. One of the traffic bores contained only LD vehicles, and the other contained mixed traffic, allowing pollutants to be apportioned between LD vehicles and diesel trucks. Particle number emission factors (particle diameter ) were found to be (3.9±1.4)×1014 and (3.3±1.3)×1015 #kg−1 fuel burned for LD vehicles and diesel trucks, respectively. Size distribution measurements showed that diesel trucks emitted at least an order of magnitude more particles for all measured sizes per unit mass of fuel burned. The relative importance of LD vehicles as a source of particles increased as decreased. Comparing the results from this study to previous measurements at the same site showed that particle number emission factors have decreased for both LD vehicles and diesel trucks since 1997. Integrating size distributions with a volume weighting showed that diesel trucks emitted 28±11 times more particles by volume (per unit fuel) than LD vehicles, consistent with the diesel/gasoline emission factor ratio for PM2.5 mass measured using gravimetric analysis of Teflon filters, reported in a companion paper. [Copyright &y& Elsevier]

Emission factors for black carbon (BC) and partide number (PN) were measured from 226 individual heavy-duty (HD) diesel trucks driving through a 1-km-long California highway tunnel in August 2006. Emission factors were based on concurrent increases in BC, PN, and CO2 concentrations (measured at 1 Hz) that corresponded to the passage of individual HD trucks. The distributions of BC and PN emission factors from individual HD trucks are skewed, meaning that a large fraction of pollution comes from a small fraction of the in-use vehicle fleet. The highest-emitting 10% of trucks were responsible for ∼40% of total BC and PN emissions from all HD trucks. BC emissions were log-normally distributed with a mean emission factor of 1.7 g kg-1 and maximum values of ∼10 g kg-1. Corresponding values for PN emission factors were 4.7 × 1015 and 4 × 1016 # kg-1. There was minimal overlap among high-emitters of these two pollutants: only 1 of the 226 HD trucks measured was found to be among the highest 10% for both BC and PN Monte Carlo resampling of the distribution of BC emission factors observed in this study revealed that uncertainties (1σ) in extrapolating from a random sample of n HD trucks to a population mean emission factor ranged from ± 4.3% for n = 10 to ± 8% for n = 300, illustrating the importance of vehicle sample sizes in emissions studies. When n = 10, sample means are more likely to be biased due to misrepresentation of high-emitters. As vehicles become cleaner on average in the futue, skewness of the emissions distributions will increase, and thus sample sizes needed to extrapolate reliably from a subset of vehicles to the entire in-use vehicle fleet will become more of a challenge. [ABSTRACT FROM AUTHOR]

Carbonyls can be toxic and highly reactive in the atmosphere. To quantify trends in carbonyl emissions from light-duty (LD) vehicles, measurements were made in a San Francisco Bay area highway tunnel bore containing essentially all LD vehicles during the summers of 1999, 2001, and 2006. The LD vehicle emission factor for formaldehyde, the most abundant carbonyl, did not change between 1999 and 2001, then decreased by 61 ± 7% between 2001 and 2006. This reduction was due to fleet turnover and the removal of MTBE from gasoline. Acetaldehyde emissions decreased by 19 ± 2% between 1999 and 2001 and by the same amount between 2001 and 2006. Absent the increased use of ethanol in gasoline after 2003, acetaldehyde emissions would have further decreased by 2006. Carbonyl emission factors for medium- (MD) and heavy-duty (HD) diesel trucks were measured in 2006 in a separate mixed-traffic bore of the tunnel. Emission factors for diesel trucks were higher than those for LD vehicles for all reported carbonyls. Diesel engine exhaust dominates over gasoline engines as a direct source of carbonyl emissions in California. Carbonyl concentrations were also measured in liquid-gasoline samples and were found to be low (<20 ppm). The gasoline brands that contained ethanol showed higher concentrations of acetaldehyde in unburned fuel versus gasoline that was formulated without ethanol. Measurements of NO2 showed a yearly rate of decrease for LO vehicle emissions similar to that of total NO! in this study. The observed NO2 ratio was 1.2 ± 0.3% and 3.1 + 0.3% for LD vehicles and diesel trucks, respectively. [ABSTRACT FROM AUTHOR]

Little is known about young men who have sex with men's use of club drugs and the risk factors associated with such use. A structured survey was administered in 2005 to 496 young men who were 18-22 years old (40% were 18-19 years old); self-identified as with a same-sex sexuality (83%), bisexual (16%), and/or had had sex with a man (97%); Caucasian (35%), African American (24%), and Latino of Mexican descent (40%). Subjects were recruited from gay-identified venues in Los Angeles, California, using a venue-based probability sampling design. Descriptive statistics revealed a high prevalence of drug and club drug use. Regression analyses revealed risk factors associated with recent club drug use, including place of residence, religiosity, disclosure of sexuality to family, frequency of attendance at bars/clubs, and involvement in sexual exchange and street economy. Limitations and implications of this research are discussed. [ABSTRACT FROM AUTHOR]

Purpose. This study investigated human immunodeficiency virus (HIV) testing and risk behaviors in a longitudinal sample of young men who have sex with men (YMSM). Design. Data came from the Healthy Young Men's study, comprising five waves of nonexperimental survey data collection every 6 months between February 2005 and January 2008. Setting. Participants were recruited from public venues in Los Angeles County in which YMSM spend time. Subjects. A total of 526 participants (24% African-American, 37% white, 39% Latino; mean age, 20.14 years; range, 18-24 years) were enrolled. Retention was 93%. Measures. Testing recency was assessed with a four-point ordinal scale. HIV risk behaviors were operationalized as binary measures of unprotected anal intercourse with multiple partners or partners with unknown or discordant serostatus, club drug use, and illicit drug use over the prior 3 months. Analysis. Correlations, Cochran's Q tests, and repeated-measures analysis of variance (ANOVA) were performed in SPSS. Analyses included all data available at each wave. Results. No significant correlations emerged between testing recency and sex risk at any wave. Repeated-measures ANOVA showed significant positive, linear change in HTV testing recency over time, but no significant changes emerged for sex risk or drug use. Conclusion. Although participation in testing increased, there was no corresponding change in HTV risk behavior. Initiatives may need to target risk behavior separately and specifically to reduce these behaviors among YMSM. [ABSTRACT FROM AUTHOR]

• Two photocatalytic architectural membranes were exposed alongside a control sample. • Specimens exposed at three California sites with different weather & pollution levels. • Photocatalytic samples showed excellent self-cleaning performance after two years. • De-NO x efficacy depended on weather, pollution, and type of photocatalytic material. • De-NO x efficacy showed seasonal effects associated with raining/dry periods. Photocatalytic self-cleaning "cool" roofs and walls can maintain high albedos, saving building cooling energy, reducing peak power demand, and mitigating the urban heat island effect. Other environmental benefits result from their de-polluting properties. Specimens from two different photocatalytic architectural membranes and a non-photocatalytic control were exposed alongside vertically, facing west, for two years at three California sites, and retrieved quarterly for testing. Photocatalytic materials showed excellent self-cleaning performance, retaining albedos of 0.74 – 0.75. By contrast, the control material exhibited an albedo loss of up to 0.10, with appreciable soiling observed by scanning electron microscopy. De-pollution capacity was assessed by quantifying NO removal and NO x deposition rates at 60 °C. Efficacy varied with exposure location, weather conditions, and the nature of the photocatalytic material. Seasonal effects were observed, with partial inhibition during the dry season and reactivation during the rainy season. [ABSTRACT FROM AUTHOR]

Rationale: Extremes of heat and particulate air pollution threaten human health and are becoming more frequent because of climate change. Understanding the health impacts of coexposure to extreme heat and air pollution is urgent. Objectives: To estimate the association of acute coexposure to extreme heat and ambient fine particulate matter (PM 2.5 ) with all-cause, cardiovascular, and respiratory mortality in California from 2014 to 2019. Methods: We used a case-crossover study design with time-stratified matching using conditional logistic regression to estimate mortality associations with acute coexposures to extreme heat and PM 2.5 . For each case day (date of death) and its control days, daily average PM 2.5 and maximum and minimum temperatures were assigned (0- to 3-day lag) on the basis of the decedent's residence census tract. Measurements and Main Results: All-cause mortality risk increased 6.1% (95% confidence interval [CI], 4.1-8.1) on extreme maximum temperature-only days and 5.0% (95% CI, 3.0-8.0) on extreme PM 2.5 -only days, compared with nonextreme days. Risk increased by 21.0% (95% CI, 6.6-37.3) on days with exposure to both extreme maximum temperature and PM 2.5 . Increased risk of cardiovascular and respiratory mortality on extreme coexposure days was 29.9% (95% CI, 3.3-63.3) and 38.0% (95% CI, -12.5 to 117.7), respectively, and were more than the sum of individual effects of extreme temperature and PM 2.5 only. A similar pattern was observed for coexposure to extreme PM 2.5 and minimum temperature. Effect estimates were larger over age 75 years. Conclusions: Short-term exposure to extreme heat and air pollution alone were individually associated with increased risk of mortality, but their coexposure had larger effects beyond the sum of their individual effects.