Researchers Gradually Gain Clarity on the Health Impacts of Wildfire Smoke

The sun as seen in Reno, Nevada on August 23, 2021. The PM 2.5 value: 313, Hazardous, according to AirNow.gov - photo: Brian Bahouth/the Ally

News Brief

Understanding the effects of wildfire smoke exposure on human health is an interdisciplinary scientific challenge. Not surprisingly, according to the U.S. Environmental Protection Agency, wildfire smoke is a multi-faceted health threat and has a direct impact on healthcare providers in persistently smoky areas. 

Wildfire smoke comes with microscopic particles that can harm the lungs, especially those with respiratory or circulatory conditions, diabetes, older adults, children, and pregnant women. 

But wildfire smoke is chemically complex and as fluid as the atmosphere, which makes modeling and forecasting difficult. As scientists have greater opportunity to study wildfire emissions and correlate that information with various health data, more is known about what fire-polluted air means for human wellness, and the news is not good.

In January of this year, the Ally reported on a research effort to better understand the chemical evolution of wildfire smoke.

Late last month it was widely reported that researchers found a correlation between exposure to wildfire smoke and susceptibility to SARS-CoV-2. 

University of Washington scientists have recently identified a link between air pollution and dementia. Scientists based the conclusion on data from a pair of well established research projects in the Seattle area. The core data set is an air quality study that dates to the late 1970s. Researchers began measuring the risk factors for dementia against air pollution maps in 1994 and subsequently found that people who have lived for over a decade where there was a small increase in the average level of fine particle pollution (PM2.5 or smaller) had a greater risk of dementia.

According to the study, daily exposure to even a small amount of wildfire smoke corresponded to a 16 percent greater hazard of “all-cause dementia.” 

Premature Births

In an effort to understand what exposure to wildfire smoke during pregnancy has on birth outcomes, Stanford University researchers analyzed data on every singleton birth (The birth of only one child with a gestation period of 20 weeks or more) in California between 2006–2012.  Researchers combined that data with “satellite-based estimates of wildfire smoke plume boundaries and high-resolution gridded estimates of surface PM2.5 concentrations …”

Results indicate, when compared to a pregnant woman unexposed to wildfire smoke, there is a 3.4 percent increase in risk of premature birth for mothers living with smoke. The research also showed that higher intensity smoke days exacerbated the likelihood of premature birth.

Unlike most pollution data, it is interesting to note that wildfire smoke affects everyone equally. “Neither exposure to smoke nor the relative impact of smoke on preterm birth differed by race/ethnicity or income in our sample.” 

Also worth noting that those who are less accustomed to wildfire smoke are more susceptible to its effects. “Impacts differed greatly by baseline smoke exposure, with mothers in regions with infrequent smoke exposure experiencing substantially larger impacts from an additional smoke-day than mothers in regions where smoke is more common.”

In the final analysis, researchers estimate that wildfire smoke accounted for 6,974 preterm births between 2007 and 2012, 3.7 percent of all early deliveries.

Smoke Forecasting

Scientists and meteorologists have been able to accurately track where wildfire smoke goes in a broad geographic sense but have a more difficult time gauging the altitude or vertical distribution of the smoke, until recently.

University of Utah chemical engineering associate professor Heather A. Holmes has developed a method of combining a meteorological model with NASA satellite data to determine whether wildfire smoke will exist at higher altitudes or down to where it will more directly impact people. More accurate predictions of the presence of smoke could potentially help sensitive groups to mitigate the impacts before they occur.

“Our hope is this technique gets incorporated into smoke forecasting as a way to improve warning systems related to smoke exposure,” Holmes said in a press release.