Extreme Heat, Wildfires Pose More Harm When Combined; California Faces Health Hazard From Converging Climate Risks

Extreme heat and wildfire smoke are independently hazardous to the human body. When combined, their effect on cardiovascular and respiratory systems is more dangerous and can affect some communities more than others.

Front Seat View of Climate Change

Of all the states in the US, California has the most wildfires which have been increasing with intense conditions. California is long referred to as an environmental leader since it lies in the front seat of the rotating list of overlapping extreme climatic events.

Between 1992 and 2020, almost all of wildfires in California were triggered by human activities, as reported by the US Forest Service. An increase in extreme temperatures contributes to the amount of wildfires that ignite in the summer months. The rising temperatures, largely due to climate change, has prolonged drought conditions in California in recent years.

A Growing Climate Threat

In a study entitled "Exploring spatial heterogeneity in synergistic effects of compound climate hazards: Extreme heat and wildfire smoke on cardiorespiratory hospitalizations in California", experts reported that climate change is increasing the frequency of both hazards, particularly in California. They found that the combined harm of extreme heat and inhalation of wildfire smoke increased the cases of hospitalizations in the state. Additionally, they also disproportionately impacted low-income communities and racially marginalized communities such as Latino, Black, and Asian residents.

Led by Chen Chen, the research team investigated the number of cardiorespiratory hospitalizations across 995 sites. These areas experience at least one day of increased exposure to wildfire smoke, one day of extremely high temperatures, and one day where both of these events were present. Experts noticed an increase in hospitalizations when both smoke and heat was recorded.

Hospitalizations on days with extreme heat and wildfire smoke events exceeded the combined hospitalizations from days with either hazard alone. This finding motivates the consideration of compound climate hazards in public health planning.

While government officials are becoming more aware of the combined effect of extreme temperatures and wildfire smoke, the researchers noted that a better understanding of the adverse health effects will improve the efforts which can be implemented for enhanced public health management.

Emerging evidence were based on satellite and environmental monitoring data taken between 2006 and 2019. It suggests that the fine particulate matter, referred to as PM2.5, coming from wildfires may be far more harmful than PM2.5 emissions from other sources such as car exhaust.

Throughout the study, the research team found that risks of smoke and heat were higher in less wealthy and more crowded communities. The effects are also more pronounced in areas with higher population of racial and ethnic minority people. Aside from the health risks, being hospitalized has other serious consequences, like losing work or school hours, or being left with costly medical bills.

It has been known that wildfire smoke can cause negative effects on a person's health when it is present for prolonged periods of time. This air pollutant can irritate the nose, throat, and eyes, while those with existing respiratory health conditions such as asthma could also suffer from worsening symptoms.