The immediate aftermath of Hurricane Katrina brought a tremendous amount of suffering to residents of the Gulf coasts of Louisiana and Mississippi. More than 800 000 homes were destroyed or became uninhabitable, communities were shattered, and families were torn apart as members were relocated to the far corners of the country. Financial and emotional stress escalated, resulting in heart attacks and high blood pressure, which could be measured immediately. Now, more than two years into the recovery period, many residents believe the worst is over, even as their neighbors show signs of suffering from long-term health problems that may be due to Katrina and its aftermath.

Many Gulf Coast residents in FEMA trailers have experienced short-term respiratory problems as a result of excessive formaldehyde exposure (from poor-quality pressed board and particleboard used as building materials). Some residents and volunteers alike have developed infections from post-storm exposures to methicillin-resistant Staphylococcus aureus, often after injuring themselves while clearing debris and rebuilding their communities.

Not surprisingly, the NIMBY (not in my back yard) syndrome has its counterpart in environmental health. The average resident will typically be far more concerned about the relatively benign but jolting visual effects of cloudy drinking water and barren lawns rather than the invisible threats posed by more serious toxins.

What is it that cannot be seen? Sometimes it is the arsenic in the soil that may or may not have been dredged up from the overflowing canals of New Orleans. Sometimes it is other heavy metals that may or may not have infiltrated residential areas when waste ponds of chemical plants overflowed along the Gulf Coast of Mississippi. Sometimes it is the ominous cancer train, trailing behind the short-term respiratory problems induced by exposure to high levels of formaldehyde in the air. Sometimes it is the dioxins that spill into the bays and climb up the food chain, entering the human body through the seafood supply. Sometimes it is the exposure to immeasurable volatile organic vapors through paints, stains, and a host of other solvents used to rebuild. Sometimes it is the E. coli and fecal coliform that regularly crop up in coastal waters when waste treatment plants run over capacity in rainy periods. So many “sometimes” mean that every resident always has at least one dangerous level of exposure in his daily routine. The total cost of these net environmental exposures will not be fully measured or seen for decades to come.

These challenges pose opportunities for innovative work for engineers of every discipline. The multiplicative effects of the environmental impacts through air, soil, and water exposure to toxins demand paradigms that transcend conventional disciplinary lines. Community activists, environmentalists, business owners, engineers, nonprofit groups, and governmental agencies would benefit from working together to create innovative solutions. The impact of these problems and the solutions to them will certainly resonate well beyond the Gulf Coast and the Katrina experience.