Vulnerability to Respiratory Symptoms Associated with Smoke Exposure from the 2017 Northern California Wildfires

Abstract

The increasing severity and frequency of wildfires poses a significant threat to human health. On October 8th, 2017 multiple fires erupted across Northern California.In response, the UC Davis EHS Center launched “WHAT-Now-CA?”. A survey was conducted on a convenience sample publicized through social and traditional media. Data were collected from one respondent per household. Preliminary results for this study represent 680 households and 1,477 individuals. Prevalence of six respiratory symptoms reported as occurring between Oct 9th and Oct 31st were documented: asthma, bronchitis, wheezing, cough, itchy or irritated eyes, and sneezing. Exposure to wildfire smoke was quantified by the level of PM2.5 at the household level calculated using the Community Multiscale Air Quality Modeling System. Robust Poisson models were fit to analyze whether participants reported any of the three major symptoms (asthma, wheezing, bronchitis). Due to clustering of individuals within households, hierarchical models were fit. The number of days people experienced PM2.5 levels above 30 ug/m3 (the maximum daily average concentration in the region during the days preceding the fires) was significantly associated with greater prevalence for respiratory symptoms (p=0.03). Every day individuals experienced PM2.5 levels above 30 ug/m3 was associated with an increased prevalence of 4%. Prior asthma (PR= 3.54, p under 0.001) and older age (PR= 1.68, p under 0.001) were significantly associated with increased prevalence of major respiratory conditions. Males had a significantly lower prevalence. As neighborhood socioeconomic status increased, respiratory symptoms decreased. These preliminary analyses suggest that increasing PM2.5 levels from wildfires predict increased odds of negative respiratory outcomes. Additionally, they suggest individual demographics (such as race, sex, age) and neighborhood socioeconomic level as well as prior asthma predict who has greater odds of developing respiratory symptoms during wildfire events.