LaPlace, Louisiana (CNN) St. John the Baptist Parish is a swampy, rural swath of Louisiana that straddles the Mississippi River. It's an unassuming place with one Walmart, a population of about 43,000, and local eateries like BRS Seafood, which had a line out the door on Easter weekend for crawfish. People stood six feet apart.

It also sits among a sprawling collection of chemical plants and oil refineries that snake along the river between Baton Rouge and New Orleans. Because of the air pollution, environmental activists have dubbed St. John and its neighboring river parishes as "Cancer Alley."

And now, the parish is known for something else: the highest death rate per capita for coronavirus in the country, according to analysis by The New York Times . It surpasses even some of the most densely populated urban hotspots that are also being crushed by the deadly virus.

A debate rages over whether there's a correlation between the petrochemical pollution and the coronavirus, which particularly strikes those with weaker immune systems. Regardless, the death toll here in recent weeks is striking by all accounts.

"It feels like what we went through with Katrina," said Geri Broussard, owner of the Baloney Funeral Home in LaPlace, Louisiana -- the main town in the parish. "It fills every space in your life, like the sky is falling."

Broussard said the funeral home is not technically overwhelmed yet but it's seeing twice the intake it normally would in a month.

According to data from the Louisiana Department of Health, 569 people have tested positive for the virus as of Wednesday, and 47 people have died. That includes 16 residents at one facility, the Southeast Louisiana War Veterans Home in Reserve, Louisiana.

The numbers are "tremendous" for a parish this size, said Dr. Christy Montegut, the parish coroner. "This virus is just overwhelming people," he added. Montegut has worked at the coroner's office for 32 years and has run a primary care practice in town for nearly 40 years. "It's just been a real surge, like an onslaught."

Montegut said the vast majority of people who died from coronavirus also had underlying health issues like hypertension, diabetes, kidney disease, and obesity. So far, he said in an interview last week, he had only seen a couple of coronavirus victims who also had cancer.

Still, activists who've been long frustrated by the air pollution here argue the correlation to a high coronavirus death rate couldn't be clearer. They point to a recent nationwide study by Harvard that found a small increase in long-term exposure leads to a large increase in the coronavirus death rate.

"We are suffering at this great percentage because ...(of) the battle we have been in for years in our systems," said Robert Taylor, Jr., who leads the group called Concerned Citizens of St. John, which has been targeting a chemical plant in LaPlace, formerly owned by DuPont for decades and now owned by Denka.

Robert Taylor speaks at a protest on Saturday.

Taylor led a socially-distant protest on Saturday outside a parish government building. Wearing masks and gloves, speakers at the protest wiped down a megaphone in between turns. "We are dying at unprecedented numbers right here in St. John," Taylor said to the crowd of mostly African Americans, which represent the majority here. The group prayed with their gloved hands outstretched and then marched around the parking lot, singing.

"If you're breathing in these chemicals every single day it automatically affects your immune system. COVID attacks mostly people with low immune systems. Those are the people that are dying," said George Handy, Sr., a member of Concerned Citizens of St. John.

The Environmental Protection Agency released a report in 2015 that drew attention to the parish after finding higher than expected levels of chloroprene in LaPlace . Chloroprene is a chemical classified by the EPA as a likely carcinogen in humans. The agency says the chemical in St. John could potentially be of concern, but it's still doing more monitoring in the area.

St. John the Baptist Parish sits among a sprawling collection of chemical plants and oil refineries along the Mississippi River between Baton Rouge and New Orleans.

According to the State of Louisiana, Denka committed $17 million to reduce emissions by 85% by the end of 2017. Denka is the second largest employer in St. John.

"Denka Performance Elastomer's operations do not have any impact on health outcomes or COVID-19 sensitivity," said Jim Harris, spokesperson for Denka. "In this critical time, it is important to look to our state and federal health officials for guidance. Health data suggests illnesses including diabetes, hypertension and obesity to be linked to COVID-19 mortality. DPE's operations are in no way related to these illnesses and health data show no negative health impacts resulting from DPE's operations."

Susan Hassig, an epidemiologist at Tulane University, has been studying the coronavirus data coming out of St. John and other river parishes.

"It certainly gave me pause, because it was so high. And then I looked at all the parishes near it, and they were also elevated," she said. "In epidemiology, we call that an ecologic correlation. So it's a big factor that connects and fits a pattern. But unless we can make the connection at the individual level, it's not something that we can really act upon."

Hassig said it's worth studying whether air pollution in St. John makes people more susceptible to coronavirus, but she noted other factors must also be taken into consideration, like smoking behavior and underlying health conditions related to other behavior.

Others argue that testing was limited in St. John early on and residents were not complying well with social distancing measures -- so much so that the sheriff had to impose a 9 p.m. curfew starting April 1.

LaPlace is the main city in St. John the Baptist Parish, the US county with the highest coronavirus death toll per capita.

Broussard, the funeral home director, described St. John as an incredibly tight-knit community where social gatherings are inherit and where "everybody knows everybody."

"It took a minute for it to set in," she observed. "You had gatherings where people had cookouts and things. I think people are finally getting the message."

Health care facilities are also scant in the parish, and the parish resides in a state well known for its poor health ratings. According to the United Health Foundation, Louisiana ranks 49th in the country in terms of overall health

Sixteen residents at the Southeast Louisiana War Veterans Home in Reserve have died of coronavirus.

Antoine Jasmine, a pastor and traveling speaker based in LaPlace, said some people in the community initially brushed it off as something that would come and go, much like the hurricanes and floods so familiar in this part of the country.

"Then eventually it shot up like a rocket. People started dropping dead. Three peopled turned into 10," he said, sitting in his church where he's been preaching in recent weeks on a livestream to an empty room. "That's when I believe the fear of what's really going on shocked."

Jasmine lost both of his parents to coronavirus on Good Friday; they died within two hours of each other. Jasmine said his family started to socially distance early on, soon after his parents grew ill in mid-March. The last time he saw them, he said, was at a church service in their usual front row seats.

Jasmine listed a range of factors that could be contributing to the high death rate in St. John, including the air pollution, but he conceded he may never know the real reasons.

"It will linger why," he said. "But I think the consolation that will be safe for me would be not to fully go into those theories, but just hold onto the strength of what I built with my parents -- and the life they lived."