People returning to what remains of the beachside town of Lahaina, Hawaii, and other Maui communities after one of the nation’s deadliest wildfire disasters face more dangers, beyond the 2,700 buildings destroyed or damaged and dozens of lives lost. The fires also left lingering health risks for humans and wildlife.
Many airborne pollutants fall to the ground, and when debris or dust is stirred up, hazardous particles can enter the air, where people can easily breathe them in.
Chemicals can also contaminate water supplies. On Aug. 11, 2023, Maui County issued an “unsafe water” alert for areas of Lahaina and Upper Kula that were affected by wildfires, warning residents to use only bottled water for drinking and cooking, and not rely on boiling tap water because of the risk of harmful chemicals.
As an environmental engineer, I work with colleagues to help communities respond to and recover from wildfires and other disasters, including the Marshall Fire in Boulder County, Colorado, and the Camp Fire that destroyed Paradise, California. Lahaina and other Maui communities face similar risks ahead.
Chemical hazards in fire debris
Residents returning to their burned neighborhoods will likely find themselves surrounded by hazards. Some are obvious, such as broken glass, nails and damaged natural gas containers. Broken power lines and gas lines may be live or leaking.
Less obvious are the chemical hazards that can reach well beyond the fire zone.
Black smoke from a fire is a sign of incomplete combustion that can produce thousands of chemicals when wood and plastics burn.
Chemicals like benzene, lead, asbestos and polycyclic aromatic hydrocarbons, or PAHs, are common in ash, runoff and sometimes water systems after fires.
Exposure to high levels of chemicals can sometimes cause immediate harm, such as nausea, vomiting, dizziness, rashes and respiratory issues. For these reasons it is critical to protect people, especially children and people with health conditions, from exposure.
Particles and vapors can enter buildings through cracks, doors, windows and other portals. Some of these pollutants settle onto surfaces, while others penetrate fabrics, stick to walls and enter air ducts.
Often buildings must be professionally cleaned or decontaminated by wildfire remediation companies. Cleaning surfaces and ducts, replacing air filters and installing HEPA filters can also help.
Outside, the ground can also become contaminated in a fire. Once the debris is removed, testing is necessary to ensure that the soil where people will replant their gardens, yards and fruit trees is free of hazardous chemicals and safe for humans and pets.
Protecting waterways and aquatic life
During firefighting and clean-up, and when it rains, pollutants can wash into waterways and end up in the ocean.
Lahaina stretches along Maui’s west coast and has long been a popular site for seeing sea turtles and other marine life. That sea life may now be at risk from pollutants from burned coastal buildings and runoff. The fire burned to the shoreline, destroying boats, docks and other vehicles, some of which sank.
Debris and sunken boats will need to be removed from the nearshore waters to protect corals. Similar to wildfires near lakes, rivers and streams, water testing will be necessary.
Communities can avoid more harmful runoff during the cleanup process by placing pollution-control barriers near storm drains, around properties and near waterways. These can help intercept pollutants flowing toward the ocean.
After the 2021 Marshall Fire in Colorado, where about 1,200 structures were destroyed, the cleanup generated 300,000 tons of waste. In Maui, debris may have to be taken off the island for disposal.
Cleanup and recovery from a disaster of this magnitude takes years. In the process, I recommend residents reach out to public health departments for advice to help them stay healthy and safe.
This article was updated Aug. 13, 2023, with new damage estimates from Maui County officials.
Andrew J. Whelton receives funding from the U.S. National Science Foundation, U.S. National Institute for Environmental Health Sciences, U.S. Environmental Protection Agency, U.S. National Institute of Occupational Safety and Health, City of Louisville, Paradise Irrigation District, Paradise Rotary Foundation, the Water Research Foundation, and crowdfunding.