Wildfires and the Changing Landscape of Air Pollution-related Health Burden in California

Where There is Smoke: An Updated Review of Environmental Contributions to Chronic Rhinosinusitis

PURPOSE

The pathogenesis of chronic rhinosinusitis (CRS) is thought to include a complex interaction between environmental exposures and host immune responses that generates a self-perpetuating inflammatory process. As molecular pathways continue to be explored, the impact of environmental exposures on CRS pathogenesis and exacerbation must not be overlooked. This review will explore the association between environmental exposures and CRS, specifically focusing on tobacco smoke, occupational inhalational exposures, air pollution, particulate matter, and wildfire smoke.

MAJOR FINDINGS

Tobacco smoke is associated with increased prevalence of CRS symptoms and formal diagnosis with worse surgical outcomes observed in both adults and children exposed to tobacco smoke. Numerous occupational exposures have been associated with increased sinonasal symptoms, though exposures and disease definitions are often poorly characterized. Pollution and microparticle exposure has been associated with an increased likelihood of CRS diagnosis, as well as increased need for surgery. Last, while wildfire smoke has been attributed to increased hospital and emergency room visits for respiratory-related complaints, no primary research has yet been performed regarding CRS and wildfire smoke, though in-vitro studies support an association.

CONCLUSIONS

Population-based studies bolstered by in-vitro mechanistic data support an association between numerous environmental exposures and the onset and severity of CRS.

Intra-Continental Transport of Western Wildfire Smoke Heightens Health Risks Across North America

Wildfires in North America, particularly in western states, have caused widespread environmental, economic, social, and health impacts. Smoke from these fires travels long distances, spreading pollutants and worsening the air quality across continents. Vulnerable groups, such as children, the elderly, and those with preexisting conditions, face heightened health risks, as do firefighters working in extreme conditions. Wildfire firefighters are of particular concern as they are fighting fires in extreme conditions with minimal protective equipment. This study examined wildfire smoke during July-August 2021, when intense fires in Canada and the western U.S. led to cross-continental smoke transport and caused significant impacts on the air quality across North America. Using the GEOS-Chem model, we simulated the transport and distribution of PM2.5 (particulate matter with a diameter of 2.5 μm or smaller), identifying significant carcinogenic risks for adults, children, and firefighters using dosimetry risk methodologies established by the U.S. EPA. Significant carcinogenic risks for adult, child, and firefighter populations due to exposure to PM2.5 were identified over the two-month period of evaluation. The findings emphasize the need for future studies to assess the toxic chemical mixtures in wildfire smoke and consider the risks to underrepresented communities.

Navigating Threats of Wildfires and Individual Rights to Adopt 100% Tobacco-Free Policy in Rural California Community Colleges

BACKGROUND

In California, all four-year public colleges have adopted 100% smoke-/tobacco-free policies (TFP) whereas community colleges (CCs), particularly rural CCs, are less likely to have tobacco-free environments. This raises concerns about health equity, particularly because smoking prevalence is higher in rural areas compared to urban. We examined policy adoption barriers and facilitators for rural California CCs with the aim of providing lessons learned to support TFP adoption by rural CCs and improve conditions for student health and well-being.

METHODS

A multiple case study of four CCs in California with (n = 2) and without (n = 2) TFPs was conducted. Semi-structured interviews with 12 campus and community stakeholders, school administrative data, and policy-relevant documents were analyzed at the case level with comparison across cases to identify key barriers, facilitators and campus-specific experiences.

RESULTS

All four CCs shared similar barriers to policy adoption including concerns about wildfires, individual rights, and fear of marginalizing people who smoke on campus. These CCs have experienced serious wildfires in the last ten years, have high community smoking prevalence, and fewer school resources for student health. For the two tobacco-free CCs, long-term wildfire mitigation efforts along with leadership support, campus/community partnerships and a collective approach involving diverse campus sectors were essential facilitators in successful TFP adoption.

CONCLUSION

Study results underscore contextual pressures and campus dynamics that impact tobacco control efforts at colleges in rural communities. Strategies to advance college TFP adoption and implementation should recognize rural cultural and community priorities.

PM2.5 associates with blood pressure: a Mendelian randomization analysis

The relationship between fine particulate matter (PM2.5) and blood pressure (BP) is a controversial issue. We conducted a two-sample Mendelian randomization (MR) analysis and identified 58 genome-wide significant single-nucleotide polymorphisms associated with PM2.5 as instrument variables. Inverse-variance weighted (IVW) was used as the primary analysis approach. MR-Egger, weighted median, simple model, and weighted model methods were selected for quality control. We found a significant negative causal association of higher genetically predicted PM2.5 levels with lower systolic BP (SBP), while no causal relationship was identified between PM2.5 and diastolic BP (DBP). For each 1 standard deviation increase in genetically predicted PM2.5 levels, the beta value (95% CI) of SBP was -0.14 (-0.25, -0.03) for IVW (p=0.02), and -0.13 (-0.22, -0.04) for weighted median (p=0.005). Increased PM2.5 concentrations can lead to decreased SBP levels. Our findings provided novel insights into the controversial topic on the causal relationship between PM2.5 and BP.

A scoping review of the impact of extreme weather events on health outcomes and healthcare utilization in rural and remote areas

BACKGROUND

Extreme weather events affect health by directly and indirectly increasing illness burdens and changing healthcare usage patterns. These effects can be especially severe in rural and remote areas, exacerbating existing health disparities, and necessitating urgent mitigation or adaptation strategies. Despite increased research on health and climate change, studies focusing on rural and remote populations remain limited. This study aimed to review the relationships among extreme weather events, healthcare utilization, and health outcomes in rural and remote populations, identify research gaps, and inform policy development for adaptation and disaster management in these settings.

METHODS

A systematic scoping review was registered and conducted following the PRISMA-ScR guidelines. The search databases included PubMed, Web of Science, Scopus, the Cochrane Library, ProQuest, and the WHO IRIS. The included studies were primary research, focused on rural or remote areas, and investigated the effects of extreme weather events on either health outcomes or healthcare utilization. There were no methodological, date or language restrictions. We excluded protocols, reviews, letters, editorials, and commentaries. Two reviewers screened and extracted all data, other reviewers were invited to resolve conflicts. Findings are presented numerically or narratively as appropriate.

RESULTS

The review included 135 studies from 31 countries, with most from high-income countries. Extreme weather events exacerbate communicable and noncommunicable diseases, including cardiorespiratory, mental health, and malnutrition, and lead to secondary impacts such as mass migration and increased poverty. Healthcare utilization patterns changed during these events, with increased demand for emergency services but reduced access to routine care due to disrupted services and financial constraints.

CONCLUSIONS

The results highlighted the essential role of community and social support in rural and remote areas during extreme weather events and the importance of primary healthcare services in disaster management. Future research should focus on developing and implementing effective mitigation and adaptation programs tailored to the unique challenges faced by these populations.

Challenges posed by climate hazards to cardiovascular health and cardiac intensive care: implications for mitigation and adaptation

Global warming, driven by increased greenhouse gas emissions, has led to unprecedented extreme weather events, contributing to higher morbidity and mortality rates from a variety of health conditions, including cardiovascular disease (CVD). The disruption of multiple planetary boundaries has increased the probability of connected, cascading, and catastrophic disasters with magnified health impacts on vulnerable populations. While the impact of climate change can be manifold, non-optimal air temperatures (NOTs) pose significant health risks from cardiovascular events. Vulnerable populations, especially those with pre-existing CVD, face increased risks of acute cardiovascular events during NOT. Factors such as age, socio-economic status, minority populations, and environmental conditions (especially air pollution) amplify these risks. With rising global surface temperatures, the frequency and intensity of heatwaves and cold spells are expected to increase, emphasizing the need to address their health impacts. The World Health Organization recommends implementing heat-health action plans, which include early warning systems, public education on recognizing heat-related symptoms, and guidelines for adjusting medications during heatwaves. Additionally, intensive care units must be prepared to handle increased patient loads and the specific challenges posed by extreme heat. Comprehensive and proactive adaptation and mitigation strategies with health as a primary consideration and measures to enhance resilience are essential to protect vulnerable populations and reduce the health burden associated with NOTs. The current educational review will explore the impact on cardiovascular events, future health projections, pathophysiology, drug interactions, and intensive care challenges and recommend actions for effective patient care.

Inhaled Pollutants of the Gero-Exposome and Later-Life Health

Inhaled air pollutants (AirP) comprise extraordinarily diverse particles, volatiles, and gases from traffic, wildfire, cigarette smoke, dust, and various other sources. These pollutants contain numerous toxic components, which collectively differ in relative levels of components, but broadly share chemical classes. Exposure and health outcomes from AirP are complex, depending on pollutant source, duration of exposure, and socioeconomic status. We discuss examples in the current literature on organ responses to AirP, with a focus on lung, arteries, and brain. Some transcriptional responses are shared. It is well accepted that AirP contributes to Alzheimer's disease and other neurodegenerative conditions in the Gero-Exposome. However, we do not know which chemical compounds initiate these changes and how activation of these transcriptional pathways is further modified by genetics and prenatal development.

Association of Short-Term Increases in Ambient Fine Particulate Matter With Hospitalization for Asthma or COPD During Wildfire Season and Other Time Periods

BACKGROUND

Short-term increases in air pollution are associated with poor asthma and COPD outcomes. Short-term elevations in fine particulate matter (PM2.5) due to wildfire smoke are becoming more common.

RESEARCH QUESTION

Are short-term increases in PM2.5 and ozone in wildfire season and in winter inversion season associated with a composite of emergency or inpatient hospitalization for asthma and COPD?

STUDY DESIGN AND METHODS

Case-crossover analyses evaluated 63,976 and 18,514 patients hospitalized for primary discharge diagnoses of asthma and COPD, respectively, between January 1999 and March 2022. Patients resided on Utah's Wasatch Front where PM2.5 and ozone were measured by Environmental Protection Agency-based monitors. ORs were calculated using Poisson regression adjusted for weather variables.

RESULTS

Asthma risk increased on the same day that PM2.5 increased during wildfire season (OR, 1.057 per + 10 μg/m3; 95% CI, 1.019-1.097; P = .003) and winter inversions (OR, 1.023 per +10 μg/m3; 95% CI, 1.010-1.037; P = .0004). Risk decreased after 1 week, but during wildfire season risk rebounded at a 4-week lag (OR, 1.098 per +10 μg/m3; 95% CI, 1.033-1.167). Asthma risk for adults during wildfire season was highest in the first 3 days after PM2.5 increases, but for children, the highest risk was delayed by 3 to 4 weeks. PM2.5 exposure was weakly associated with COPD hospitalization. Ozone exposure was not associated with elevated risks.

INTERPRETATION

In a large urban population, short-term increases in PM2.5 during wildfire season were associated with asthma hospitalization, and the effect sizes were greater than for PM2.5 during inversion season.

Measuring long-term exposure to wildfire PM2.5 in California: Time-varying inequities in environmental burden

Wildfires have become more frequent and intense due to climate change and outdoor wildfire fine particulate matter (PM2.5) concentrations differ from relatively smoothly varying total PM2.5. Thus, we introduced a conceptual model for computing long-term wildfire PM2.5 and assessed disproportionate exposures among marginalized communities. We used monitoring data and statistical techniques to characterize annual wildfire PM2.5 exposure based on intermittent and extreme daily wildfire PM2.5 concentrations in California census tracts (2006 to 2020). Metrics included: 1) weeks with wildfire PM2.5 < 5 μg/m3; 2) days with non-zero wildfire PM2.5; 3) mean wildfire PM2.5 during peak exposure week; 4) smoke waves (≥2 consecutive days with <15 μg/m3 wildfire PM2.5); and 5) mean annual wildfire PM2.5 concentration. We classified tracts by their racial/ethnic composition and CalEnviroScreen (CES) score, an environmental and social vulnerability composite measure. We examined associations of CES and racial/ethnic composition with the wildfire PM2.5 metrics using mixed-effects models. Averaged 2006 to 2020, we detected little difference in exposure by CES score or racial/ethnic composition, except for non-Hispanic American Indian and Alaska Native populations, where a 1-SD increase was associated with higher exposure for 4/5 metrics. CES or racial/ethnic × year interaction term models revealed exposure disparities in some years. Compared to their California-wide representation, the exposed populations of non-Hispanic American Indian and Alaska Native (1.68×, 95% CI: 1.01 to 2.81), white (1.13×, 95% CI: 0.99 to 1.32), and multiracial (1.06×, 95% CI: 0.97 to 1.23) people were over-represented from 2006 to 2020. In conclusion, during our study period in California, we detected disproportionate long-term wildfire PM2.5 exposure for several racial/ethnic groups.

Clearing the Air: Understanding the Impact of Wildfire Smoke on Asthma and COPD

Wildfires are a global natural phenomenon. In North America, wildfires have not only become more frequent, but also more severe and longer in duration, a trend ascribed to climate change combined with large fuel stores left from modern fire suppression. The intensification of wildfire activity has significant implications for planetary health and public health, as exposure to fine particulate matter (PM2.5) in wildfire smoke is linked to adverse health effects. This review focuses on respiratory morbidity from wildfire smoke exposure. Inhalation of wildfire PM2.5 causes lung injury via oxidative stress, local and systemic inflammation, airway epithelium compromise, and increased vulnerability to infection. Wildfire PM2.5 exposure results in exacerbations of pre-existing asthma and chronic obstructive pulmonary disease, with an escalation in healthcare utilization, including emergency department visits and hospitalizations. Wildfire smoke exposure may be associated with asthma onset, long-term impairment of lung function, and increased all-cause mortality. Children, older adults, occupationally-exposed groups, and possibly women are the most at risk from wildfire smoke. Future research is needed to clarify best practices for risk mitigation and wildfire management.

The Effects of Wildfire Smoke on Asthma and Allergy

PURPOSE OF REVIEW

To review the recent literature on the effects of wildfire smoke (WFS) exposure on asthma and allergic disease, and on potential mechanisms of disease.

RECENT FINDINGS

Spatiotemporal modeling and increased ground-level monitoring data are allowing a more detailed picture of the health effects of WFS exposure to emerge, especially with regard to asthma. There is also epidemiologic and some experimental evidence to suggest that WFS exposure increases allergic predisposition and upper airway or sinonasal disease, though much of the literature in this area is focused more generally on PM2.5 and is not specific for WFS. Experimental evidence for mechanisms includes disruption of epithelial integrity with downstream effects on inflammatory or immune pathways, but experimental models to date have not consistently reflected human disease in this area. Exposure to WFS has an acute detrimental effect on asthma. Potential mechanisms are suggested by in vitro and animal studies.