The weather system that would become history-making Hurricane Laura spun out of a tropical wave that moved into the Atlantic Ocean off the West African coast on Aug. 16. Five days later the system strengthened into a tropical storm, with sustained winds of 45 miles per hour. Passing over the island of Hispaniola, Laura killed at least 31 people in Haiti and four in the Dominican Republic before moving across Cuba and into the Gulf of Mexico, still as a tropical storm.

By Aug. 25, Laura was a Category 1 hurricane with sustained winds of 75 mph. But over the next 24 hours, the storm underwent a process known as "rapid intensification": Feeding off of abnormally warm water temperatures in the Gulf, the storm exploded into a Category 4 monster with sustained winds of nearly 145 mph — almost a catastrophic Category 5. Laura's intensification is one of the fastest on record in the region. Scientists say such events, which complicate evacuation plans, are likely to become more common as much of the atmospheric heat trapped by rising greenhouse gas levels ends up in the oceans. This has important implications for Southern states along the Gulf and Atlantic coasts, where ocean waters tend to be warmer and where most hurricanes strike.

Laura was a record-breaking storm in what's already been an unusually active hurricane season — the first in which nine tropical storms formed before August and 13 before September. The first major hurricane of the 2020 Atlantic season and the strongest storm to hit Louisiana since 1856, Laura was also the earliest 12th-named storm on record in the North Atlantic basin, the first Category 4 storm on record to hit that part of the Gulf, and the fifth-strongest storm on record to hit the U.S. For a moment, it even appeared that Laura and another hurricane might hit along the Gulf Coast at the same time, but then Marco weakened, making landfall on Aug. 24 near the mouth of the Mississippi River as a weak tropical storm. As Laura approached the U.S., the country was grappling with another major climate-related disaster: raging wildfires in California, the worst in the state's history.

Laura hit land near Cameron, Louisiana, at about 1 a.m. on Aug. 27. The seat of Cameron Parish, Cameron is a census-designated place near the Texas border that's been repeatedly leveled by hurricanes. In 1957, Audrey killed 300 people there. In 2005, Rita destroyed much of the community, which had been evacuated, preventing massive loss of lives. Residents were still rebuilding from that disaster when Ike hit in 2008. As some storm-battered residents gave up and moved, Cameron's population fell from about 1,965 people in 2000 to just 406 by 2010, many of them living in RVs that they can drive away at a moment's notice.

Warned that Laura's storm surge would be "unsurvivable," Cameron residents evacuated ahead of the hurricane, which came ashore with 150 mph winds and a surge of 9 to 12 feet — less than the 20 feet that had been predicted. There have been no reported deaths in Cameron Parish directly related to Laura. But reporters who visited the community since the storm have emerged to tell stories of widespread devastation, with boats blocking streets, every cell tower in the parish down, and caskets disinterred from cemeteries. After witnessing the destruction in hard-hit Lake Charles, Louisiana, one local business owner told a Texas TV station, "I lost my mind."

So far, 27 deaths along the Gulf Coast — 22 in Louisiana and five in Texas — have been attributed to Hurricane Laura. Six of the deaths in Louisiana came after the storm passed and were classified as heat-related. Others have been blamed on carbon monoxide poisoning from the improper use of generators amid widespread and continuing power outages, including five people killed in a single home in Louisiana. In all, about 600,000 homes lost power in the storm, and all nine transmission lines that deliver power into southwestern Louisiana were catastrophically damaged. A week after Laura hit, more than 300,000 people were still without power across Louisiana and Texas as those states experienced dangerous levels of heat and humidity — all in the midst of the deadly COVID-19 respiratory pandemic that's hit Louisiana especially hard. In Lake Charles and surrounding Calcasieu Parish, which bore the storm's brunt, 90% of households remain without power.

People in storm-affected areas are also contending with another problem worsened by a warming climate and intensified flooding: clouds of mosquitos so thick they're being blamed for the deaths of hundreds of cattle and some horses. That's led to spraying of chemical pesticides, which have their own health drawbacks. Calcasieu Parish is among the communities that began spraying for mosquitos since Laura; its spray program typically uses synthetic pyrethroids. While these chemicals are widely used and less toxic than some insecticides, they can cause respiratory, eye, and skin irritation. Epidemiological studies have also raised concerns about pyrethroids' potentially harmful effects on sperm, reproductive hormones, pregnancy outcomes, and early neurobehavioral development after in utero exposure; other studies have pointed to adverse effects on the immune system, heart, liver, kidneys, and blood. In addition, the spraying can have an effect on the local ecology, since pyrethroids kill insects other than mosquitos. And while they were once thought not to bioaccumulate, more recent research has found pyrethroids build up in the bodies of some species of dolphins and fish, and pass on to human babies through their mothers' milk.

Unknown toxic threats

While Florida is the state that's been hit by the most hurricanes since record keeping began, Texas and Louisiana are also among the top four most storm-vulnerable states, along with North Carolina. That matters for the entire nation, since the Gulf Coast is home to about half of all U.S. oil refining capacity. But it has particular implications for communities near those refineries and the region's other petrochemical and industrial facilities — communities that are disproportionately non-white and low-income.

The Gulf of Mexico off the Louisiana and Texas coasts is a center of the offshore oil and gas industry, and there were about 1,400 active wells along the path Laura took through the Gulf. SkyTruth, a West Virginia-based group that uses satellite imagery for environmental monitoring, has reported seeing no signs so far of any large-scale leaks or spills. "This is a vast improvement over Hurricane Katrina, when hundreds of offshore pipelines were damaged by mobile drilling rigs that had been blown loose from their moorings, and dragged their anchors across miles of seafloor," the group noted in a Facebook post. The Louisiana Mid-Continent Oil & Gas Association, an industry group, said in a statement that "building upon lessons learned from past storms, like Katrina, Ike and Rita, companies are continuously improving preparation and response plans to lessen storm impacts and shorten the time it takes to recover."

But that doesn't mean Laura didn't cause spills. Julie Dermansky, a New Orleans-based photographer and reporter, flew over at least 20 miles of storm-affected areas and documented extensive oil sheens in wetlands for the Louisiana Environmental Action Network and DeSmogBlog. "For miles along the western Louisiana coastline near the Texas border, I spotted large swathes of land and water that appeared coated with oil, visible as the floodwaters receded between the small communities of Grand Chenier and Cameron," Dermansky wrote at DeSmogBlog. "On September 2 and 3, I also documented oil sheen in waterways along the bayous from Cameron north to the city of Lake Charles and as far east as New Iberia, roughly 130 miles west of New Orleans."

In all, 31 oil and chemical spills were reported after Laura to the Coast Guard's National Response Center, the federal agency responsible for recording and monitoring such incidents. One of the spills was connected to a fire at BioLab, a pool chemical company in Westlake, Louisiana, near Lake Charles, that sent black clouds of smoke and chlorine gas into the sky and forced nearby residents in homes without power to shelter in place for more than a day. Of all the reported spills, 20 appear to have involved coastal waters. Another involved a spill into a marsh of an unknown quantity of crude oil from a storage tank containing up to 40,000 barrels owned by Plains All American, an oil pipeline and storage company based in Houston. In past disasters, these initial reports have sometimes underestimated the size of spills.

Hurricanes bring significant air pollution as well. Before Laura made landfall, as is normal practice, refineries and petrochemical plants went into shutdown mode; that involves burning off excess chemicals in pipes in a process called "flaring," which also occurs at fracking sites. In the two days before the storm hit, Texas facilities doing this released more than 4 million pounds of extra air pollution, according to reports companies made to state environmental regulators that were analyzed by the nonprofit Environmental Defense Fund for NPR. Much of that was a single release of carbon dioxide, a greenhouse gas, from a methanol production facility in Beaumont, Texas, according to the Houston Chronicle. Other pollutants released included cancer-causing benzene, and nitrogen oxides that can trigger respiratory problems. Similar data does not exist for Louisiana. But residents of the historically African American community of Mossville, Louisiana, a petrochemical center on the outskirts of Lake Charles, returned to their homes days after the storm only to report suffering from headaches that they suspect are tied to pollution releases.

Studies have linked flaring to adverse health effects in nearby communities, including premature births. Environmental advocates in Texas are currently organizing to get the state to ban routine flaring by 2025, and in fact held an online forum about flaring the day Laura hit. The pre-storm releases and storm-related spills come on top of the chronic pollution from refineries, limits on which have been relaxed under the Trump administration. And while spikes in air pollution are likely as a hurricane arrives, monitoring it can be difficult as states take air quality monitors offline to keep them from being damaged; the environmental departments in both Louisiana and Texas informed the Environmental Protection Agency (EPA) they would be doing so. Pollution monitors also failed due to power loss, the Associated Press reported.

It could take awhile to understand just how toxic Laura was. After Hurricane Harvey hit Houston in 2017, it took months for the public to learn about some of the hundreds of spills that occurred, according to a report by the EPA's Inspector General. A Louisiana Department of Natural Resources spokesperson told DeSmogBlog this week that it's still too early to assess the storm's damage. But residents say the dearth of information is business as usual. As Carla Chrisco, a Lake Charles lawyer who evacuated the city before Laura, told the Associated Press, residents "generally don't get any information except what the industry puts out."