Social Vulnerability in US Communities Affected by Wildfire Smoke, 2011 to 2021

Jason Vargo, PhD, MPH; Brooke Lappe, MPH; Maria C. Mirabelli, PhD, MPH; Kathryn C. Conlon, PhD, MPH


Am J Public Health. 2023;113(7):759-767. 

In This Article

Abstract and Introduction


Objectives: To describe demographic and social characteristics of US communities exposed to wildfire smoke.

Methods: Using satellite-collected data on wildfire smoke with the locations of population centers in the coterminous United States, we identified communities potentially exposed to light-, medium-, and heavy-density smoke plumes for each day from 2011 to 2021. We linked days of exposure to smoke in each category of smoke plume density with 2010 US Census data and community characteristics from the Centers for Disease Control and Prevention's Social Vulnerability Index to describe the co-occurrence of smoke exposure and social disadvantage.

Results: During the 2011-to-2021 study period, increases in the number of days of heavy smoke were observed in communities representing 87.3% of the US population, with notably large increases in communities characterized by racial or ethnic minority status, limited English proficiency, lower educational attainment, and crowded housing conditions.

Conclusions: From 2011 to 2021, wildfire smoke exposures in the United States increased. As smoke exposure becomes more frequent and intense, interventions that address communities with social disadvantages might maximize their public health impact.


In recent years, wildfires have, on average, burned more than double the acreage per year compared with earlier decades. In the 1990s, 3.3 million acres were burned per year, while in 2021, 7.1 million acres were burned.[1] Smoke from wildfires compromises air quality by increasing concentrations of particulate matter (PM), ozone, polycyclic aromatic hydrocarbons, volatile organic compounds, and other harmful air pollutants[2–4] that have well-described impacts on respiratory disease and all-cause mortality.[5,6] Projected wildfire trends in the United States predict in-creasing risk of exposure to wildfire smoke[7] because of increases in weather- and climate-related factors associated with wildfire risk, including heat, drought, and wind speed.[8]

Smoke, also referred to as wildland or wildfire smoke, can travel thousands of miles, potentially exposing distant populations, including communities less prepared for smoke.[9,10] The movement and coverage of wildfire smoke over large areas may result in similar exposures for neighboring communities; however, wildfire risk can vary spatially by population susceptibility and adaptive capacity, or the ability to absorb, recover, and modify exposure to wildfires.[10–15] As with other ambient climate hazards, such as extreme heat, the social and community characteristics that determine adaptive capacity may play an important role in explaining health disparities related to wildfire smoke.[16,17]

Wildfire smoke exposure is associated with asthma exacerbations, chronic obstructive pulmonary disease, respiratory infections, myocardial infarction, ischemic heart disease, heart failure, dysrhythmia, pulmonary embolism, ischemic stroke and transient ischemic attack, out-of-hospital cardiac arrests, and all-cause mortality.[18–20] Public health recommendations to reduce exposure to wildfire smoke currently include recommendations to stay indoors in places with adequate air filtration, reduce activity during smoke events, reduce other sources of indoor air pollution, use air filters, and, for those who cannot stay indoors (e.g., agricultural and outdoor workers),[21] wear suitable respiratory protection when outdoors.[22]

Making these types of changes can be especially difficult for people with limited resources.[11,15,23,24] For example, people without high-quality indoor air filtration at home, those without access to clean air spaces, and people experiencing homelessness might be particularly challenged to make these changes to reduce their personal exposure to wildfire smoke. Recent work shows that wealthier households are more aware of wildfire smoke, allowing them to take protective actions such as closing windows and doors or wearing respirators, seeking out protective devices such as air filters, adjusting their lifestyles to avoid exposures, or more easily temporarily evacuating.[25] Many of the self-protective actions are costly and, therefore, unlikely to benefit some populations.

Demographic, economic, institutional, and sociocultural characteristics such as socioeconomic status, household composition, racial or ethnic minority status, language, and housing type may affect an individual's ability to prepare for, respond to, and recover from wildfire smoke. If these characteristics are associated with an unequal risk of exposure, then these individuals face greater risk of respiratory, cardiovascular, and other adverse health outcomes. We conducted this study to describe wildfire smoke exposure from January 2011 to December 2021 across the United States and to assess the extent to which wildfire smoke exposures overlap with social and community characteristics that might affect adaptive capacity and, as a result, health.