California Air Resources Board

Executive Summary

The 2018 Camp Fire was the deadliest wildfire in California history. At least 85 people died as the catastrophic wildfire burned through Butte County, destroying nearly 19,000 buildings and most of the town of Paradise. The fire generated a large plume of heavy smoke that traveled thousands of miles. The smoke caused dangerously high levels of air pollution in the Sacramento Valley and Bay Area in particular, for a period of about two weeks.

Staff at the California Air Resources Board (CARB) compared air quality data from the Camp Fire with three other large wildfires in 2018 that burned mostly vegetation. When wildfires burn structures, they produce a range of harmful and toxic substances. CARB’s analysis shows this was indeed the case during the Camp Fire, when elevated levels of lead and zinc were detected, as well as calcium, iron and manganese. Some of these metals traveled more than 150 miles, and were detected in the air as far away as San Jose and Modesto.

Particulate matter (PM) is typically the biggest health concern from wildfire smoke. Particles from smoke tend to be very small (with diameters of 2.5 micrometers [μm] and smaller), and can be inhaled into the deepest recesses of the lung. This size of particulate matter is often referred to as PM_2.5. The tiniest, ultrafine particles in PM_2.5 can pass directly into the bloodstream where they can affect the heart and other organs. During the 2018 Camp Fire, maximum PM_2.5 levels for the period from November 8 through November 22
were more than three times the average levels seen during the same time period from 2010 to 2017.

The number of buildings burned during this fire was significant, and not something traditionally seen in California wildfires. The Carr Fire, which burned over 50 percent more acreage in the Shasta-Trinity National Forest in late July and August of 2018, destroyed about 1,600 buildings. The Mendocino Complex Fire, occurring during the same time period, burned almost three times the acreage of the Camp Fire, but destroyed only about 250 buildings. CARB staff used data from these wildfires, as well as that collected during the Ferguson Fire in Mariposa County, which burned mostly inaccessible wildland areas during the same basic time period (late summer 2018). The goal was to better understand the air quality differences that might occur between wildfires that burn primarily vegetation, such as the Ferguson Fire, and those that burn more structures. Staff also examined potential additional health impacts that could arise from structure-burning wildfires in more populated areas.

All four wildfires showed increases in PM_2.5 levels, with higher concentrations measured at sites closer to the fires. Data from all four fires showed increases in the metal composition of PM_2.5 as well. Only the Camp Fire, however, saw significant increases in both lead and zinc. Lead was highest in Chico, which was the closest available monitoring site to the Camp Fire, while zinc levels were slightly higher at the monitoring site in Modesto, roughly 150 miles away. It is unclear if sources other than the Camp Fire may have contributed to the zinc detected in Modesto. Other components, such as organic carbon and potassium ions, used as a way to chemically trace the presence of smoke, were elevated during all the wildfires, with the highest levels also occurring in Chico during the Camp Fire. Data collected during the four wildfires showed no significant differences in other chemical components of PM_2.5.

The health impacts of air pollutants produced by wildfires can be significant. While the elevated levels of lead detected in Chico during the Camp Fire only lasted for about a day, these numbers are still concerning, since lead is considered a toxic air contaminant and any increased exposure can be harmful. Lead exposure has been linked to high blood pressure, reproductive effects and cancer in adults. Infants and young children are especially sensitive to low levels of lead that are known to cause behavioral changes and learning deficits.

The short-term spikes in particulate matter from the Camp Fire and other wildfires included in this analysis were comparable to industrial and mobile source pollution levels seen in countries like China and India. Both countries show subsequent increases in respiratory diseases and infections, and chronic heart and lung disease, resulting in increased medical visits, hospital admissions, and risk
of death.

In general, short-term exposure (days or weeks) to PM_2.5 and wildfire smoke has been strongly linked to increasing severity of asthma; other respiratory disease, such as chronic obstructive pulmonary disease (COPD); inflammation or infections, including bronchitis and pneumonia; emergency department visits; and hospital admissions. Long-term exposure to PM_2.5 is linked to a wide range of human health effects, such as respiratory and heart-related illnesses and hospitalizations, adverse brain effects, depression, memory loss, learning disorders, reduced lung function growth in children and premature death.

CARB is sponsoring several studies that will provide additional insight into both the short-term and long-term health impacts of wildfire smoke. CARB-funded investigators are currently studying the associations between short-term exposure to wildfire PM_2.5 and loss of work days and increases in asthma attacks. CARB is also funding a long-term health effects study in which primates were naturally exposed during infancy to wildfires and continue to be monitored throughout adulthood. Additionally, CARB is pursuing future research to examine the effects of repeated short-term exposures to PM_2.5 that are becoming more common with large wildfires and longer wildfire
seasons in California.

Increased monitoring of wildfire pollution, particularly during fires with higher incidences of structures burning, is paramount to understand the impacts these different types of fires have on air quality as well as the health of California’s citizens. Partly as a result of this analysis, and the recent severity and scale of wildfires in California, CARB is proposing an expansion of monitoring efforts, including an increased response with portable samplers for both particulate matter and air toxics. In addition, CARB will modify sampling frequencies and durations as needed and increase its cooperation with CalOES to better understand the components of each type of wildfire smoke, while also providing the public with more detailed information about smoke impacts.