Cardiovascular and Cerebrovascular Emergency Department Visits Associated With Wildfire Smoke Exposure in California in 2015

Illuminating Stakeholder Perspectives at the Intersection of Air Quality Health Risk Communication and Cardiac Rehabilitation

There is ample evidence of adverse cardiovascular health outcomes associated with exposure to air pollution and cardiac rehabilitation patients are at increased risk for future adverse health events related to air quality. Risk communication and health messaging about recommended behaviors to reduce exposure to air pollution can be integrated into existing care routines and structures. How this can be achieved most appropriately and effectively is not well understood. A focus group design is used to investigate cardiovascular patient and provider experiences, attitudes and beliefs about the risks of air pollution, related health risk messaging and factors that may influence integrating that topic into patient care and communication. Three discussions were hosted, one with cardiac patients, a second with non-physician cardiac rehabilitation providers and a third with physicians who treat cardiac patients. A within-case thematic inductive analysis of each discussion is used to understand the nature of communication, logistics, guidance and overall substance of the cardiac rehabilitation educational experience. Results suggest that air pollution may be an unrecognized risk factor for cardiac patients and cardiac rehabilitation is a prime setting for communicating air pollution health risk messaging. However, to effectively integrate air quality health risk messaging into cardiac rehabilitation, it is critical to account for the existing knowledge-base and behaviors of both providers and patients.

Mapping Modeled Exposure of Wildland Fire Smoke for Human Health Studies in California

Wildland fire smoke exposure affects a broad proportion of the U.S. population and is increasing due to climate change, settlement patterns and fire seclusion. Significant public health questions surrounding its effects remain, including the impact on cardiovascular disease and maternal health. Using atmospheric chemical transport modeling, we examined general air quality with and without wildland fire smoke PM2.5. The 24-h average concentration of PM2.5 from all sources in 12-km gridded output from all sources in California (2007-2013) was 4.91 μg/m3. The average concentration of fire-PM2.5 in California by year was 1.22 μg/m3 (~25% of total PM2.5). The fire-PM2.5 daily mean was estimated at 4.40 μg/m3 in a high fire year (2008). Based on the model-derived fire-PM2.5 data, 97.4% of California's population lived in a county that experienced at least one episode of high smoke exposure ("smokewave") from 2007-2013. Photochemical model predictions of wildfire impacts on daily average PM2.5 carbon (organic and elemental) compared to rural monitors in California compared well for most years but tended to over-estimate wildfire impacts for 2008 (2.0 μg/m3 bias) and 2013 (1.6 μg/m3 bias) while underestimating for 2009 (-2.1 μg/m3 bias). The modeling system isolated wildfire and PM2.5 from other sources at monitored and unmonitored locations, which is important for understanding population exposure in health studies. Further work is needed to refine model predictions of wildland fire impacts on air quality in order to increase confidence in the model for future assessments. Atmospheric modeling can be a useful tool to assess broad geographic scale exposure for epidemiologic studies and to examine scenario-based health impacts.

The Associations Between Clinical Respiratory Outcomes and Ambient Wildfire Smoke Exposure Among Pediatric Asthma Patients at National Jewish Health, 2012-2015

Wildfires are a growing threat in the United States. At a population level, exposure to ambient wildfire smoke is known to be associated with severe asthma outcomes such as hospitalizations. However, little work has been done on subacute clinical asthma outcomes, especially in sensitive populations. This study retrospectively investigated associations between ambient wildfire smoke exposure and measures of lung function and asthma control, Forced Expiratory Volume in 1 Second (FEV1) and the Asthma Control Test (ACT) and Children's Asthma Control Test (CACT) test scores, during nonurgent clinic visits. The study population consisted of pediatric asthma patients (ages 4-21; n = 1,404 for FEV1 and n = 395 for ACT/CACT) at National Jewish Health, a respiratory referral hospital in Denver, Colorado, and therefore represents a more severe asthma phenotype than the general pediatric asthma population. Wildfire smoke-related PM2.5 at patients' residential ZIP codes was characterized using satellite-derived smoke polygons from NOAA's Hazard Mapping System combined with kriging of ground-based U.S. EPA monitors. Mixed effect models were used to estimate associations between clinical outcomes and smoke PM2.5 exposure, controlling for known risk factors and confounders. Among older children aged 12-21 we found that wildfire PM2.5 was associated with lower FEV1 the next day but higher FEV1 the day after. We found no associations between wildfire PM2.5 and FEV1 in younger children or between wildfire PM2.5 and asthma control measured by the ACT/CACT in all ages. We speculate that rescue medication usage by older children may decrease respiratory symptoms caused by wildfire smoke.

Hospital, health, and community burden after oil refinery fires, Richmond, California 2007 and 2012

INTRODUCTION

Emergency Departments experience a significant census burst after disasters. The aim of this study is to describe patient presentations at Emergency Departments in Contra Costa County, California following chemical release incidents at an oil refinery in 2007 and 2012. Specific areas of focus include hospital and community burden with an emphasis on disease classes.

METHODS

Searching 4 weeks before through 4 weeks after each event, Emergency Department abstracts identified patients living in Contra Costa County and seeking care there or in neighboring Alameda County. City and ZIP-code of residence established proximity to the refinery. This provided the following contrast groups: Event (2007, 2012), time (before, after), location (bayside, rest of county), and within bayside, warned or not warned to shelter in place. Using the Multi-Level Clinical Classification Software, we classified primary health groups recorded 4 weeks before and after the events, then summarized the data, calculated rates, and made tables, graphs, and maps to highlight findings.

RESULTS

Number of visits meeting selection criteria totalled 105020 records. Visits increased modestly but statistically significantly after the 2007 incident. After the 2012 incident, two Emergency Departments took the brunt of the surge. Censuses increased from less than 600 a week each to respectively 5719 and 3072 the first week, with the greatest number 2 days post-event. It took 4 weeks for censuses to return to normal. The most common diagnosis groups that spiked were nervous/sensory, respiratory, circulatory, and injury. Bayside communities had statistically significant increases in residents seeking care. Specifically, visits of residents in warned communities nearest the refinery increased by a factor of 3.7 while visits of residents in other nearby un-warned communities increased by a factor of 1.5.

CONCLUSIONS

The 2012 Emergency Department census peaked in the first week and did not return to normal for 4 weeks. Diagnoses changed to reflect conditions associated with reactions to chemical exposures. Surrounding communities and nearby hospitals experienced significant emergent burdens. In addition to changes from such events in patient diagnoses and community burden, the discussion highlights the long-term implications of failures to require adequate monitoring and warning systems and failures of health planning.

Femoral Artery Sclerosis Evaluation by Tissue Doppler in Patients with Hypertension

Background

The aim of this study was to evaluate the early femoral sclerosis in hypertensive patients by using tissue Doppler imaging (TDI).

Material/Methods

One hundred patients with hypertension were recruited and divided into group A (femoral artery intima-media thicknesses (IMT) ≥1.0 mm) and group B (femoral artery IMT <1.0 mm) with 50 cases in each group based on the femoral IMT. In addition, 50 healthy controls were also included in this study. Femoral wall structure and femoral artery IMT were examined by using high frequency ultrasound. Pulsed wave (PW)-TDI was used to obtain the motion curve of the posterior wall of the femoral artery. First (T1) and second (T2) peak duration were also obtained.

Results

The IMT of group A, group B, and the healthy control group were 1.17±0.12 mm, 0.74±0.11 mm, and 0.71±0.09 mm respectively with significant statistical difference (P<0.05). The first peak duration (T1) of the 3 groups (group A, group B, and healthy control group) were 135.6±16.6 ms, 134.5±18.5 ms, and 129.8±12.4 ms, respectively without statistical difference (F=1.868 P=0.158). The second peak duration (T2) of group A, group B, and the healthy control group were 234.7±39.8 ms, 209.3±34.9 ms, and 169.8±19.5 ms respectively with statistically significant difference (F=50.411 P=0.000). The diagnostic sensitivity, specificity area under the curve (AUC) and cutoff value for early arteriosclerosis diagnosis of femoral artery by T1 was 56.0% (95% CI: 41.3–70.0%), 66.0% (95% CI: 51.2–78.8%), AUC=0.54 (95% CI: 0.42–0.66) and 130.5 ms respectively. And it was 64.0% (95% CI: 49.2–77.1%), 62.0% (95% CI: 47.2–75.4%), AUC=0.69 (95% CI: 0.59–0.80) and 214.5 ms respectively for T2.

Conclusions

TDI can be used as an effective index for early femoral artery sclerosis before femoral artery IMT changes.

Prevalence and profile of "seasonal frequent flyers" with chronic heart disease: Analysis of 1598 patients and 4588 patient-years follow-up

BACKGROUND

Peaks and troughs in cardiovascular events correlated with seasonal change is well established from an epidemiological perspective but not a clinical one.

METHODS

Retrospective analysis of the recruitment, baseline characteristics and outcomes during minimum 12-month exposure to all four seasons in 1598 disease-management trial patients hospitalised with chronic heart disease. Seasonality was prospectively defined as ≥4 hospitalisations (all-cause) AND >45% of related bed-days occurring in any one season during median 988 (IQR 653, 1394) days follow-up.

RESULTS

Patients (39% female) were aged 70 ± 12 years and had a combination of coronary artery disease (58%), heart failure (54%), atrial fibrillation (50%) and multimorbidity. Overall, 29.9% of patients displayed a pattern of seasonality. Independent correlates of seasonality were female gender (adjusted OR 1.27, 95% CI 1.01-1.61; p = 0.042), mild cognitive impairment (adjusted OR 1.51, 95% CI 1.16-1.97; p = 0.002), greater multimorbidity (OR 1.20, 95% CI 1.15-1.26 per Charlson Comorbidity Index Score; p < 0.001), higher systolic (OR 1.01, 95%CI 1.00-1.01 per 1 mmHg; p = 0.002) and lower diastolic (OR 0.99, 95% CI 0.98-1.00 per 1 mmHg; p = 0.002) blood pressure. These patients were more than two-fold more likely to die (adjusted HR 2.16, 95% CI 1.60-2.90; p < 0.001) with the highest and lowest number of deaths occurring during spring (31.7%) and summer (19.9%), respectively.

CONCLUSIONS

Despite high quality care and regardless of their diagnosis, we identified a significant proportion of "seasonal frequent flyers" with concurrent poor survival in this real-world cohort of patients with chronic heart disease.

Wildfire smoke exposure under climate change: impact on respiratory health of affected communities

PURPOSE OF REVIEW

In this review, we describe the current status of the literature regarding respiratory health related to wildfire smoke exposure, anticipated future impacts under a changing climate, and strategies to reduce respiratory health impacts of wildfire smoke.

RECENT FINDINGS

Recent findings confirm associations between wildfire smoke exposure and respiratory health outcomes, with the clearest evidence for exacerbations of asthma. Although previous evidence showed a clear association between wildfire smoke and chronic obstructive pulmonary disease, findings from recent studies are more mixed. Current evidence in support of an association between respiratory infections and wildfire smoke exposure is also mixed. Only one study has investigated long-term respiratory health impacts of wildfire smoke, and few studies have estimated future health impacts of wildfires under likely climate change scenarios.

SUMMARY

Wildfire activity has been increasing over the past several decades and is likely to continue to do so as climate change progresses, which, combined with a growing population, means that population exposure to and respiratory health impacts of wildfire smoke is likely to grow in the future. More research is needed to understand which population subgroups are most vulnerable to wildfire smoke exposure and the long-term respiratory health impacts of these high pollution events.

Cardiopulmonary Effects of Fine Particulate Matter Exposure among Older Adults, during Wildfire and Non-Wildfire Periods, in the United States 2008-2010

BACKGROUND

The effects of exposure to fine particulate matter ([Formula: see text]) during wildland fires are not well understood in comparison with [Formula: see text] exposures from other sources.

OBJECTIVES

We examined the cardiopulmonary effects of short-term exposure to [Formula: see text] on smoke days in the United States to evaluate whether health effects are consistent with those during non-smoke days.

METHODS

We examined cardiopulmonary hospitalizations among adults [Formula: see text] y of age, in U.S. counties ([Formula: see text]) within [Formula: see text] of 123 large wildfires during 2008-2010. We evaluated associations during smoke and non-smoke days and examined variability with respect to modeled and observed exposure metrics. Poisson regression was used to estimate county-specific effects at lag days 0-6 (L0-6), adjusted for day of week, temperature, humidity, and seasonal trend. We used meta-analyses to combine county-specific effects and estimate overall percentage differences in hospitalizations expressed per [Formula: see text] increase in [Formula: see text].

RESULTS

Exposure to [Formula: see text], on all days and locations, was associated with increased hospitalizations on smoke and non-smoke days using modeled exposure metrics. The estimated effects persisted across multiple lags, with a percentage increase of 1.08% [95% confidence interval (CI): 0.28, 1.89] on smoke days and 0.67% (95% CI: [Formula: see text], 1.44) on non-smoke days for respiratory and 0.61% (95% CI: 0.09, 1.14) on smoke days and 0.69% (95% CI: 0.19, 1.2) on non-smoke days for cardiovascular outcomes on L1. For asthma-related hospitalizations, the percentage increase was greater on smoke days [6.9% (95% CI: 3.71, 10.11)] than non-smoke days [1.34% (95% CI: [Formula: see text], 3.77)] on L1.

CONCLUSIONS

The increased risk of [Formula: see text]-related cardiopulmonary hospitalizations was similar on smoke and non-smoke days across multiple lags and exposure metrics, whereas risk for asthma-related hospitalizations was higher during smoke days. https://doi.org/10.1289/EHP3860.

Contribution of Wildland-Fire Smoke to US PM2.5 and Its Influence on Recent Trends

Seasonal-mean concentrations of particulate matter with diameters smaller than 2.5 μm (PM_2.5) have been decreasing across the United States (US) for several decades, with large reductions in spring and summer in the eastern US. In contrast, summertime-mean PM_2.5 in the western US has not significantly decreased. Wildfires, a large source of summertime PM_2.5 in the western US, have been increasing in frequency and burned area in recent decades. Increases in extreme PM_2.5 events attributable to wildland fires have been observed in wildfire-prone regions, but it is unclear how these increases impact trends in seasonal-mean PM_2.5. Using two distinct methods, (1) interpolated surface observations combined with satellite-based smoke plume estimates and (2) the GEOS-Chem chemical transport model (CTM), we identify recent trends (2006-2016) in summer smoke, nonsmoke, and total PM_2.5 across the US. We observe significant decreases in nonsmoke influenced PM_2.5 in the western US and find increases in summer-mean smoke PM_2.5 in fire-prone regions, although these are not statistically significant due to large interannual variability in the abundance of smoke. These results indicate that without the influence of wildland fires, we would expect to have observed improvements in summer fine particle pollution in the western US but likely weaker improvements than those observed in the eastern US.

High-Throughput Video Processing of Heart Rate Responses in Multiple Wild-type Embryonic Zebrafish per Imaging Field

Heart rate assays in wild-type zebrafish embryos have been limited to analysis of one embryo per video/imaging field. Here we present for the first time a platform for high-throughput derivation of heart rate from multiple zebrafish (Danio rerio) embryos per imaging field, which is capable of quickly processing thousands of videos and ideal for multi-well platforms with multiple fish/well. This approach relies on use of 2-day post fertilization wild-type embryos, and uses only bright-field imaging, circumventing requirement for anesthesia or restraint, costly software/hardware, or fluorescently-labeled animals. Our original scripts (1) locate the heart and record pixel intensity fluctuations generated by each cardiac cycle using a robust image processing routine, and (2) process intensity data to derive heart rate. To demonstrate assay utility, we exposed embryos to the drugs epinephrine and clonidine, which increased or decreased heart rate, respectively. Exposure to organic extracts of air pollution-derived particulate matter, including diesel or biodiesel exhausts, or wood smoke, all complex environmental mixtures, decreased heart rate to varying degrees. Comparison against an established lower-throughput method indicated robust assay fidelity. As all code and executable files are publicly available, this approach may expedite cardiotoxicity screening of compounds as diverse as small molecule drugs and complex chemical mixtures.

Stress Testing the Capacity of Health Systems to Manage Climate Change-Related Shocks and Stresses

Vulnerability and adaptation assessments can provide valuable input to foster climate-resilient health systems. However, these assessments often do not explore the potential health risks of climate change far outside the range of recent experience with extreme weather events and other climate-related hazards. Climate and health stress tests are designed to increase the capacity of health systems and related sectors to manage potentially disruptive climate-related shocks and stresses. Stress tests focus on hypothetical scenarios, during which it would be difficult for the health system to maintain its essential function of providing services to protect population health. The stress test explores approaches to effectively manage acute and chronic climate-related events and conditions that could directly impact health systems, and climate-related events in non-health sectors that can indirectly impact health outcomes and/or health system function. We provide detailed methods and guidance for conducting climate and health stress tests, centering on three primary activities: (1) preparing and scoping the stress test; (2) successfully conducting the stress test; and (3) communicating the results to key stakeholders to facilitate policy and programmatic reforms.

The San Diego 2007 wildfires and Medi-Cal emergency department presentations, inpatient hospitalizations, and outpatient visits: An observational study of smoke exposure periods and a bidirectional case-crossover analysis

BACKGROUND

The frequency and intensity of wildfires is anticipated to increase as climate change creates longer, warmer, and drier seasons. Particulate matter (PM) from wildfire smoke has been linked to adverse respiratory and possibly cardiovascular outcomes. Children, older adults, and persons with underlying respiratory and cardiovascular conditions are thought to be particularly vulnerable. This study examines the healthcare utilization of Medi-Cal recipients during the fall 2007 San Diego wildfires, which exposed millions of persons to wildfire smoke.

METHODS AND FINDINGS

Respiratory and cardiovascular International Classification of Diseases (ICD)-9 codes were identified from Medi-Cal fee-for-service claims for emergency department presentations, inpatient hospitalizations, and outpatient visits. For a respiratory index and a cardiovascular index of key diagnoses and individual diagnoses, we calculated rate ratios (RRs) for the study population and different age groups for 3 consecutive 5-day exposure periods (P1 [October 22-26], P2 [October 27-31], and P3 [November 1-5]) versus pre-fire comparison periods matched on day of week (5-day periods starting 3, 4, 5, 6, 8, and 9 weeks before each exposed period). We used a bidirectional symmetric case-crossover design to examine emergency department presentations with any respiratory diagnosis and asthma specifically, with exposure based on modeled wildfire-derived fine inhalable particles that are 2.5 micrometers and smaller (PM2.5). We used conditional logistic regression to estimate odds ratios (ORs), adjusting for temperature and relative humidity, to assess same-day and moving averages. We also evaluated the United States Environmental Protection Agency (EPA)'s Air Quality Index (AQI) with this conditional logistic regression method. We identified 21,353 inpatient hospitalizations, 25,922 emergency department presentations, and 297,698 outpatient visits between August 16 and December 15, 2007. During P1, total emergency department presentations were no different than the reference periods (1,071 versus 1,062.2; RR 1.01; 95% confidence interval [CI] 0.95-1.08), those for respiratory diagnoses increased by 34% (288 versus 215.3; RR 1.34; 95% CI 1.18-1.52), and those for asthma increased by 112% (58 versus 27.3; RR 2.12; 95% CI 1.57-2.86). Some visit types continued to be elevated in later time frames, e.g., a 72% increase in outpatient visits for acute bronchitis in P2. Among children aged 0-4, emergency department presentations for respiratory diagnoses increased by 70% in P1, and very young children (0-1) experienced a 243% increase for asthma diagnoses. Associated with a 10 μg/m3 increase in PM2.5 (72-hour moving average), we found 1.08 (95% CI 1.04-1.13) times greater odds of an emergency department presentation for asthma. The AQI level "unhealthy for sensitive groups" was associated with significantly elevated odds of an emergency department presentation for respiratory conditions the day following exposure, compared to the AQI level "good" (OR 1.73; 95% CI 1.18-2.53). Study limitations include the use of patient home address to estimate exposures and demographic differences between Medi-Cal beneficiaries and the general population.

CONCLUSIONS

Respiratory diagnoses, especially asthma, were elevated during the wildfires in the vulnerable population of Medi-Cal beneficiaries. Wildfire-related healthcare utilization appeared to persist beyond the initial high-exposure period. Increased adverse health events were apparent even at mildly degraded AQI levels. Significant increases in health events, especially for respiratory conditions and among young children, are expected based on projected climate scenarios of wildfire frequency in California and globally.