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Aguilera, R, Gershunov A, Benmarhnia T.  2019.  Atmospheric rivers impact California's coastal water quality via extreme precipitation. Science of the Total Environment. 671:488-494.   10.1016/j.scitotenv.2019.03.318   AbstractWebsite

Precipitation in California is projected to become more volatile: less frequent but more extreme as global warming pushes midlatitude frontal cyclones further poleward while bolstering the atmospheric rivers (ARs), which tend to produce the region's extreme rainfall. Pollutant accumulation and delivery to coastal waters can be expected to increase, as lengthening dry spells will be increasingly punctuated by more extreme precipitation events. Coastal pollution exposes human populations to high levels of fecal bacteria and associated pathogens, which can cause a variety of health impacts. Consequently, studying the impact of atmospheric rivers as the mechanism generating pulses of water pollution in coastal areas is relevant for public health and in the context of climate change. We aimed to quantify the links between precipitation events and water quality in order to explore meteorological causes as first steps toward effective early warning systems for the benefit of population health in California and beyond. We used historical gridded daily precipitation and weekly multiple fecal bacteria indicators at similar to 500 monitoring locations in California's coastal waters to identify weekly associations between precipitation and water quality during 2003-09 using canonical correlation analysis to account for the nested/clustered nature of longitudinal data. We then quantified, using a recently published catalog of atmospheric rivers, the proportion of coastal pollution events attributable to ARs. Association between precipitation and fecal bacteria was strongest in Southern California. Over two-thirds of coastal water pollution spikes exceeding one standard deviation were associated with ARs. This work highlights the importance of skillful AR landfall predictions in reducing vulnerability to extreme weather improving resilience of human populations in a varying and changing climate. Quantifying the impacts of ARs on waterborne diseases is important for planning effective preventive strategies for public health. (C) 2019 Elsevier B.V. All rights reserved.

Benmarhnia, T, Bailey Z, Kaiser D, Auger N, King N, Kaufman JS.  2016.  A Difference-in-Differences Approach to Assess the Effect of a Heat Action Plan on Heat-Related Mortality, and Differences in Effectiveness According to Sex, Age, and Socioeconomic Status (Montreal, Quebec). Environmental Health Perspectives. 124:1694-1699.   10.1289/EHP203   AbstractWebsite

BACKGROUND: The impact of heat waves on mortality and health inequalities is well documented. Very few studies have assessed the effectiveness of heat action plans (HAPs) on health, and none has used quasi-experimental methods to estimate causal effects of such programs.OBJECTIVES: We developed a quasi-experimental method to estimate the causal effects associated with HAPs that allows the identification of heterogeneity across subpopulations, and to apply this method specifically to the case of the Montreal (Quebec, Canada) HAP.METHODS: A difference-in-differences approach was undertaken using Montreal death registry data for the summers of 2000-2007 to assess the effectiveness of the Montreal HAP, implemented in 2004, on mortality. To study equity in the effect of HAP implementation, we assessed whether the program effects were heterogeneous across sex (male vs. female), age (>= 65 years vs. < 65 years), and neighborhood education levels (first vs. third tertile). We conducted sensitivity analyses to assess the validity of the estimated causal effect of the HAP program.RESULTS: We found evidence that the HAP contributed to reducing mortality on hot days, and that the mortality reduction attributable to the program was greater for elderly people and people living in low-education neighborhoods.CONCLUSION: These findings show promise for programs aimed at reducing the impact of extreme temperatures and health inequities. We propose a new quasi-experimental approach that can be easily applied to evaluate the impact of any program or intervention triggered when daily thresholds are reached.

Leas, EC, Pierce JP, Benmarhnia T, White MM, Noble ML, Trinidad DR, Strong DR.  2018.  Effectiveness of pharmaceutical smoking cessation aids in a nationally representative cohort of American smokers. Jnci-Journal of the National Cancer Institute. 110:581-587.   10.1093/jnci/djx240   AbstractWebsite

Background: Despite strong efficacy in randomized trials, the population effectiveness of pharmaceutical aids in long-term smoking cessation is lacking, possibly because of confounding (factors that are associated with both pharmaceutical aid use and difficulty quitting). Matching techniques in longitudinal studies can remove this confounding bias. Methods: Using the nationally representative Tobacco Use Supplement to the Current Population Survey (TUS-CPS), we assessed the effectiveness of medications to aid quitting among baseline adult smokers who attempted to quit prior to one year of follow-up in two longitudinal studies: 2002-2003 and 2010-2011. Pharmaceutical aid users and nonusers with complete data (n = 2129) were matched using propensity score models with 12 potential confounders (age, sex, race-ethnicity, education, smoking intensity, nicotine dependence, previous quit history, self-efficacy to quit, smoke-free homes, survey year, and cessation aid use). Using matched data sets, logistic regression models were fit to assess whether use of any individual pharmaceutical aid increased the proportion of patients who were abstinent for 30 days or more at follow-up. Results: Propensity score matching markedly improved balance on the potential confounders between the pharmaceutical aid use groups. Using matched samples to provide a balanced comparison, there was no evidence that use of varenicline (adjusted risk difference [aRD] = 0.01, 95% confidence interval (CI] = -0.07 to Oil), bupropion (aRD = 0.02, 95% CI = -0.04 to 0.09), or nicotine replacement (aRD = 0.01, 95% CI = -0.03 to 0.06) increased the probability of 30 days or more smoking abstinence at one-year follow-up. Conclusions: The lack of effectiveness of pharmaceutical aids in increasing long-term cessation in population samples is not an artifact caused by confounded analyses. A possible explanation is that counseling and support interventions provided in efficacy trials are rarely delivered in the general population.

Vijayaraghavan, M, Benmarnhia T, Pierce JP, White MM, Kempster J, Shi YY, Trinidad DR, Messer K.  2018.  Income disparities in smoking cessation and the diffusion of smoke-free homes among US smokers: Results from two longitudinal surveys. Plos One. 13   10.1371/journal.pone.0201467   AbstractWebsite

Background Lower rates of successful quitting among low-income populations in the United States may be from slower dissemination of smoke-free homes, a predictor of cessation. Objectives To explore the role of smoke-free homes in cessation behavior across income levels. Participants Current smokers who were >= 18 years and who participated in the longitudinal 2002-2003 (n = 2801) or 2010-2011 (n = 2723) Tobacco Use Supplements to the Current Population Survey. Measurements We categorized income as multiples of the federal poverty level (FPL) (<300% FPL versus >= 300% FPL). We examined the association of smoke-free homes with 1+day quit attempts and 30+days abstinence at 1-year follow-up. We then conducted a mediation analysis to examine the extent that smoke-free homes contributed to income disparities in 30+days abstinence. Results Between the two surveys, heavy smoking (>= 1 pack/day) declined by 17%, and smoking prevalence declined by 15% among those with higher-incomes (>300%FPL). Although similar in 2002, the prevalence of smoke-free homes was 33% lower among individuals living <300% FPL than those living >= 300% FPL. Although the quit attempt rate was similar, the 30 +days abstinence rate was higher in the 2010-11 cohort than in 2002-3 cohort (20.6% versus 15.5%, p<0.008). Whereas smoking >= 1 pack/ day was associated with lower odds of 30 +days abstinence (Adjusted odds ratio [AOR] 0.7; 95% CI 0.5-0.9), having a higher income (AOR 1.9, 95% CI 1.4-2.6) and a smoke-free home (AOR 1.6, 95% CI 1.2-2.1) were associated with greater odds of 30+day abstinence. Differential changes in smoke-free homes across income groups between the two surveys contributed to 36% (95% CI 35.7-36.3) of the observed income disparity in 30+days abstinence. Conclusions Increasing the diffusion of smoke-free homes among low-income populations may attenuate at least a third of the income disparities in smoking cessation, highlighting the need for interventions to increase adoption of smoke-free homes among low-income households.