Environmental Monitoring

Maui Wildfire Data: Ash

The Maui wildfires released ash and soot into the air. The ash was produced from the burning of structures, including wood, tiles, insulation, vegetation, and other items. Settled ash can be washed away by rain or become airborne. People could be exposed to ash by breathing it in, ingesting it, or touching it. DOH and partners are working to remove ash and debris and safely store them at the West Maui Temporary Debris Storage site.

Ash Sampling

DOH collected a multi-part ash sample from 100 homes in the Lahaina burn area on November 7 and 8, 2023, and separately collected a multi-part ash sample from eight burned homes in Kula on September 21, 2023 (Figure 1).

DOH collected samples from the foundations of burned homes, including construction materials, furniture, and other objects. DOH used these samples to evaluate levels of harmful fire-related substances and to determine whether additional monitoring and controls are needed to protect the public.

Torrent Laboratory analyzed the samples for heavy metals, dioxins, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), pesticides, and other substances. The primary metals of concern include lead (often from burned wood coated with lead-based paint) and arsenic from treated wood and tiles. DOH compared levels of substances in the ash samples to DOH’s Environmental Action Levels (EALs), which are considered health-based screening levels, to evaluate potential risks to human health.

Ash data provided by DOH in accordance with DOH protocols.
DOH EAL: Hawaii DOH Environmental Action Level for screening. An entry of “—” means the analyte does not have an EAL. 
An entry of “—” for analytical results means the sample was not analyzed for that parameter, and thus, results were not reported.
Bolded numbers indicate exceedances of DOH’s EAL for unrestricted soil use, which assumes a residential exposure scenario.
ND: Non-detect
TEQ Dioxins: “Toxic equivalent concentration” that allows the reporting of multiple dioxin/dioxin-like chemicals as a single value based on their relative toxicities.
¹Screening values represent soil action levels for unrestricted current or future land use that address direct exposure to humans. The EALs are from Table I-1 of DOH’s TGM EAL Surfer (found here: Environmental Hazard Evaluation and Environmental Action Levels – HEER Office (hawaii.gov)) at the time of data release (December 2023). These EALs are toxicity-based and consider bioavailability of substance but do not account for natural background levels.

Ash data provided by DOH in accordance with DOH protocols.
DOH EAL: Hawaii DOH Environmental Action Level for screening. An entry of “—” means the analyte does not have an EAL. 
An entry of “—” for analytical results means the sample was not analyzed for that parameter, and thus, results were not reported.
Bolded numbers indicate exceedances of DOH’s EAL for unrestricted soil use, which assumes a residential exposure scenario.
ND: Non-detect
TEQ Dioxins: “Toxic equivalent concentration” that allows the reporting of multiple dioxin/dioxin-like chemicals as a single value based on their relative toxicities.
¹Screening values represent soil action levels for unrestricted current or future land use that address direct exposure to humans. The EALs are from Table I-1 of DOH’s TGM EAL Surfer (found here: Environmental Hazard Evaluation and Environmental Action Levels – HEER Office (hawaii.gov)) at the time of data release (December 2023). These EALs are toxicity-based and consider bioavailability of substance but do not account for natural background levels.

• Applying Soiltac® (by EPA) to stabilize the ash and prevent it from becoming airborne, as people could breathe, contact, or incidentally ingest airborne dust.
• Removing debris (by USACE) and restricting access to areas where ash and debris are present.

• Collecting samples to confirm fire-related substance levels are below levels of public health concern before allowing public access or issuing completion letters for rebuilding.
• Using air monitoring to make sure debris removal does not affect air quality. Continuing to monitor air across the area.