City-Specific Air Quality Warnings for Improved Asthma Self-Management.

INTRODUCTION: This study presents a framework for identifying "high-risk" days for asthma attacks associated with elevated concentrations of criteria pollutants using local information to warn citizens on days when the concentrations differ from Environmental Protection Agency Air Quality Index (AQI) warnings. Studies that consider the unique mixture of pollutants and the health data specific to a city provide additional information for asthma self-management. This framework is applied to air pollution and asthma data to identify supplemental warning days in Houston, Texas. METHODS: A four-step framework was established to identify days with pollutant levels that pose meaningful increased risk for asthma attacks compared with baseline. Historical associations between 18,542 ambulance-treated asthma attacks and air pollutant concentrations in Houston, Texas (2004-2016; analyzed in 2018), were analyzed using a case-crossover study design with conditional logistic regression. Days with historically high associations between pollution and asthma attacks were identified as supplemental warning days. RESULTS: Days with 8-hour maximum ozone >66.6 parts per billion for the 3 previous days and same-day 24-hour nitrogen dioxide >19.3 parts per billion pose an RR of 15% above baseline; concentrations above these levels pose an increased risk of 15% (RR=1.15, 95% CI=1.14, 1.16) and 30% (RR=1.30, 95% CI=1.29, 1.32), respectively. These warnings add an additional 12% days per year over the AQI warnings. CONCLUSIONS: Houston uses this framework to identify supplemental air quality warnings to improve asthma self-management. Supplemental days reflect risk lower than the National Ambient Air Quality Standards and consecutive poor air quality days, differing from the AQI.

Analyzing Who, When, and Where: Data for Better Targeting of Resources for School-Based Asthma Interventions.

BACKGROUND: Rates of uncontrolled asthma vary by demographics, space, and time. This article uses data on ambulance-treated asthma attacks in children to analyze these variations so that school districts can improve their asthma management interventions. METHODS: Incidence rates of 1826 ambulance-treated asthma attacks for children aged 5-18 years were calculated for school zones for elementary, middle, and high schools in the Houston (Texas) Independent School District (HISD). Zones with rates in the upper quartile were identified as the highest rate zones and were compared with other school zones in the district by demographics, location, and timing of attacks. RESULTS: The ambulance-treated asthma rate was respectively 5, 3, and 2 times greater in the highest rate school zones compared with all other school zones for those school levels. Ambulance-treated asthma attacks in the high-rate school zones occurred most at midday and in the evening and high-rate zones were often geographically contiguous. Schools in the high-rate zones had a higher percent of socioeconomically disadvantaged students and were more often without a school nurse. CONCLUSION: Spatial and temporal analysis of ambulance data can be valuable tools for schools to focus policy and program interventions for the students in need of improved asthma management.

Measured and estimated benzene and volatile organic carbon (VOC) emissions at a major U.S. refinery/chemical plant: Comparison and prioritization.

Estimates of emissions for processes and point sources at petroleum refineries and chemical plants provide the foundation for many other environmental evaluations and policy decisions. The most commonly used method, based on emission factors, results in unreliable estimates. More information regarding the actual emissions within a facility is necessary to provide a foundation for improving emission factors and prioritizing which emission factors most need improvement. Identification of which emission factors both perform poorly and introduce the largest error is needed to provide such a prioritization. To address this need, benzene and volatile organic compound (VOC) emissions within a major chemical plant/refinery were measured and compared with emission factor estimates. The results of this study indicate estimated emissions were never higher and commonly lower than the measured emissions. At one source location, VOC emissions were found to be largely representative of those measured (i.e., the catalytic reformer), but more often, emissions were significantly underestimated (e.g., up to 448 times greater than estimated at a floating roof tank). The sources with both the largest relative error between the estimate and the measurement and the largest magnitude of emissions in this study were a wastewater treatment process, an aromatics concentration unit and benzene extraction unit process area, and two sets of tanks (sets 7 and 8). Emission factors for these sources are priorities for further evaluation and improvement in this chemical plant/refinery. This study presents empirical data that demonstrate the need to validate and improve emission factors. Emission factors needing improvement are prioritized by identifying those that are weak models and introduce the largest error in magnitude of emissions. The results can also be used to prioritize evaluations of the emissions sources and controls, and any operational conditions or erroneous assumptions that may be contributing to the error.

Using community level strategies to reduce asthma attacks triggered by outdoor air pollution: a case crossover analysis.

BACKGROUND: Evidence indicates that asthma attacks can be triggered by exposure to ambient air pollutants, however, detailed pollution information is missing from asthma action plans. Asthma is commonly associated with four criteria pollutants with standards derived by the United States Environmental Protection Agency. Since multiple pollutants trigger attacks and risks depend upon city-specific mixtures of pollutants, there is lack of specific guidance to reduce exposure. Until multi-pollutant statistical modeling fully addresses this gap, some guidance on pollutant attack risk is required. This study examines the risks from exposure to the asthma-related pollutants in a large metropolitan city and defines the city-specific association between attacks and pollutant mixtures. Our goal is that city-specific pollution risks be incorporated into individual asthma action plans as additional guidance to prevent attacks. METHODS: Case-crossover analysis and conditional logistic regression were used to measure the association between ozone, fine particulate matter, nitrogen dioxide, sulfur dioxide and carbon monoxide pollution and 11,754 emergency medical service ambulance treated asthma attacks in Houston, Texas from 2004-2011. Both single and multi-pollutant models are presented. RESULTS: In Houston, ozone and nitrogen dioxide are important triggers (RR = 1.05; 95% CI: 1.00, 1.09), (RR = 1.10; 95% CI: 1.05, 1.15) with 20 and 8 ppb increase in ozone and nitrogen dioxide, respectively, in a multi-pollutant model. Both pollutants are simultaneously high at certain times of the year. The risk attributed to these pollutants differs when they are considered together, especially as concentrations increase. Cumulative exposure for ozone (0-2 day lag) is of concern, whereas for nitrogen dioxide the concern is with single day exposure. Persons at highest risk are aged 46-66, African Americans, and males. CONCLUSIONS: Accounting for cumulative and concomitant outdoor pollutant exposure is important to effectively attribute risk for triggering of an asthma attack, especially as concentrations increase. Improved asthma action plans for Houston individuals should warn of these pollutants, their trends, correlation and cumulative effects. Our Houston based study identifies nitrogen dioxide levels and the three-day exposure to ozone to be of concern whereas current single pollutant based national standards do not.

Geospatial analysis for targeting out-of-hospital cardiac arrest intervention.

BACKGROUND: Bystander cardiopulmonary resuscitation (BCPR) provides an opportunity for decreasing cardiac mortality. Rates of out-of-hospital cardiac arrest (OHCA) in which resuscitation was performed vary within cities and across demographics. PURPOSE: To identify contiguous geographic census tracts with high OHCA, low BCPR rates and high-risk demographics to effectively target culturally appropriate community-based intervention planning. METHODS: In 2012, a cohort of 11,389 emergency medical services (EMS) OHCA cases from Houston TX (2004-2011) was linked to census tracts. Multivariable logistic regression analyses were used to identify demographics of contiguous geographic census tracts with the highest OHCA rates. Within these tracts, BCPR rates were evaluated. The combination of information was used to develop a plan to better target interventions. RESULTS: Contiguous census tracts of high OHCA rates were identified; the average rate per 100,000 within versus outside the identified tracts is 106.0 (SD 23.7) to 55.8 (SD 19.7). Tracts with a low BCPR rate (37.7%) relative to a high OHCA rate were identified. In a separate analysis, individuals at highest relative risk of OHCA were found to be African Americans, to have low income or education levels, and to be older individuals. For every 1% increase in African Americans in a census tract, there is an increase of 2.7% in the relative risk of the census tract belonging to a high-OHCA-rate region (95% CI=2.0%, 3.5%). CONCLUSIONS: Geospatial analysis can provide important information on the contiguous areas of high OHCA rates and low BCPR rates with the aim of more effectively targeting interventions and ultimately decreasing cardiac deaths.

A case-crossover analysis of out-of-hospital cardiac arrest and air pollution.

BACKGROUND: Evidence of an association between the exposure to air pollution and overall cardiovascular morbidity and mortality is increasingly found in the literature. However, results from studies of the association between acute air pollution exposure and risk of out-of-hospital cardiac arrest (OHCA) are inconsistent for fine particulate matter, and, although pathophysiological evidence indicates a plausible link between OHCA and ozone, none has been reported. Approximately 300 000 persons in the United States experience an OHCA each year, of which >90% die. Understanding the association provides important information to protect public health. METHODS AND RESULTS: The association between OHCA and air pollution concentrations hours and days before onset was assessed by using a time-stratified case-crossover design using 11 677 emergency medical service-logged OHCA events between 2004 and 2011 in Houston, Texas. Air pollution concentrations were obtained from an extensive area monitor network. An average increase of 6 µg/m(3) in fine particulate matter 2 days before onset was associated with an increased risk of OHCA (1.046; 95% confidence interval, 1.012-1.082). A 20-ppb ozone increase for the 8-hour average daily maximum was associated with an increased risk of OHCA on the day of the event (1.039; 95% confidence interval, 1.005-1.073). Each 20-ppb increase in ozone in the previous 1 to 3 hours was associated with an increased risk of OHCA (1.044; 95% confidence interval, 1.004-1.085). Relative risk estimates were higher for men, blacks, or those aged >65 years. CONCLUSIONS: The findings confirm the link between OHCA and fine particulate matter and introduce evidence of a similar link with ozone.

Statistical investigation of polychlorinated dibenzo-p-dioxins and dibenzofurans in the ambient air of Houston, Texas.

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (dioxins and furans) are persistent, bioaccumulative and highly toxic chemical constituents that appear in the environment at very low and difficult to measure levels. Although dioxins and furans are widely recognized as toxic contaminants needing regulation, their temporal and spatial concentration profiles and the factors impacting their partitioning and congener distribution are only moderately understood. This paper presents the results from one of the most extensive ambient air dioxin and furan sampling efforts conducted in a geographic area to date. The data consist of monthly ambient concentrations of 17 of the most toxic congeners of dioxins and furans collected at five locations in Houston, Texas over a calendar year. The results showed a total annual mean dioxin and furan congener concentration of 1047 fg/m3 and an annual mean summation operatorI-TEQ concentration of 15 fg I-TEQ/m3 (16 fg WHO-TEQ/m3). These results, when compared with proximate data from the USEPA National Dioxin Ambient Monitoring Network (NDAMN), revealed significant (at the P0.05 level) differences between Houston and the NDAMN sites, suggesting the existence of local dioxin sources. A temporal analysis of the data showed that the congener concentration distribution varies over time, depending on the level of chlorination, type of congener, and temperature. The results also suggested that the fluctuations of congener concentrations and I-TEQ concentrations are closely correlated with minimum relative humidity, mean temperature, and mean NOx concentration.