Particulate matter from California wildfires linked to cardiovascular and cerebrovascular events – “It’s a local problem, but it’s also a national problem”

Desdemona Despair

By L.A. McKeown
12 April 2018

(TCTMD) – New data show a surprising pattern of increased emergency department (ED) visits for cardiovascular and cerebrovascular problems on days when wildfires are burning in California. Researchers say the fine particulate matter created by the fires poses significant risk beyond the state’s borders, and in particular to people over age 65, who appear to be most greatly affected.

The study adds to accumulating data on the association between air pollution and cardiovascular risk, and highlights the vulnerability of elderly patients with cardiac and vascular risk factors living in areas where the fires are common.

“It’s a local problem, but it’s also a national problem,” said the study’s senior author Ana G. Rappold, PhD (US Environmental Protection Agency, Durham, NC), in an interview with TCTMD. She noted that it is not uncommon for particulate matter from a wildfire in Alaska or the northwest territories to be detectable in the southern region of the United States, for example.

For the study, investigators led by Zachary S. Wettstein (University of California, San Francisco) looked at ED visits from May through September 2015, when intense wildfires were occurring in northern and central California. On days when smoke was most dense, visits for all-cause and individual cardiovascular diagnoses were highest across all age groups. For patients over age 65, this translated to a 42% increase in ED visits for MI, a 22% increase in visits for ischemic heart disease, and a 22% increased risk of heart failure. Visits for hypertension also were increased in elderly patients regardless of the density of the smoke, while increases in pulmonary embolism were greatest with medium and dense smoke.

Elevated risk of cerebrovascular disease was seen for all adults regardless of the condition of the smoke, while ischemic stroke diagnoses were increased only with lengthy exposure to smoky conditions in the age 65 and over group. Respiratory problems as a reason for the ED visit also were increased among all adults on the heavier smoke days, but again were most pronounced in the elderly. [more]

Particulate Matter From California Wildfires Linked to Cardiovascular and Cerebrovascular Events

ABSTRACT: Wildfire smoke is known to exacerbate respiratory conditions; however, evidence for cardiovascular and cerebrovascular events has been inconsistent, despite biological plausibility.

Methods and Results: A population‐based epidemiologic analysis was conducted for daily cardiovascular and cerebrovascular emergency department (ED) visits and wildfire smoke exposure in 2015 among adults in 8 California air basins. A quasi‐Poisson regression model was used for zip code‐level counts of ED visits, adjusting for heat index, day of week, seasonality, and population. Satellite‐imaged smoke plumes were classified as light, medium, or dense based on model‐estimated concentrations of fine particulate matter. Relative risk was determined for smoky days for lag days 0 to 4. Rates of ED visits by age‐ and sex‐stratified groups were also examined. Rates of all‐cause cardiovascular ED visits were elevated across all lags, with the greatest increase on dense smoke days and among those aged ≥65 years at lag 0 (relative risk 1.15, 95% confidence interval [1.09, 1.22]). All‐cause cerebrovascular visits were associated with smoke, especially among those 65 years and older, (1.22 [1.00, 1.49], dense smoke, lag 1). Respiratory conditions were also increased, as anticipated (1.18 [1.08, 1.28], adults >65 years, dense smoke, lag 1). No association was found for the control condition, acute appendicitis. Elevated risks for individual diagnoses included myocardial infarction, ischemic heart disease, heart failure, dysrhythmia, pulmonary embolism, ischemic stroke, and transient ischemic attack.

Conclusions: Analysis of an extensive wildfire season found smoke exposure to be associated with cardiovascular and cerebrovascular ED visits for all adults, particularly for those over aged 65 years.

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