CHEMICAL OF THE MONTH - Particulate Matter (PM)

By Caitlion O. Hunter, Esq.

A service program of RISE St. James; Caitlion O. Hunter, Esq.; Tim Schütz, PhD Researcher, Anthropology University of California, Irvine; and The Community Scientist (TCS) Research Team

The sight of a huge flare at night or a sugarcane field burning is nothing uncommon in St. James Parish. The clouds of black smoke are full of a pollutant called particulate matter. Particulate matter (PM) is not one specific chemical but rather a term for very small particles that can stay airborne due to their small size. Unlike sand, dust, or soot, PM is not visible to the naked eye. The two common designations are PM2.5 and PM10, where the numbers stand for micrometers (or microns) of size. A grain of sand is about 90 microns, while human hair is about 70 microns in diameter. PM2.5 is therefore about 30 times smaller than the width of a human hair! 

Although small in size, PM2.5 is especially dangerous to human health because it can penetrate deeply into the lungs if inhaled and can also enter the bloodstream. Children are more at risk because of their smaller bodies and developing lungs. Besides lung issues, high PM exposure is linked to type 2 diabetes, heart attacks or irregular heartbeat, and dying from cancer. A 2024 study by Kimberly Terrell and Gianna St. Julien found that “a majority of adverse birth outcomes in Louisiana,” meaning thousands of low birth weight and preterm births, “are linked to air pollution exposure or disadvantage” (i.e., low-income community and/or people of color). Furthermore, at least two recent studies have indicated that environmental pollutants such as PM2.5 increase the susceptibility to COVID‐19 incidences.

While PM10 is not as dangerous as PM2.5, since it cannot be absorbed into the bloodstream, it is physically irritating to the lungs, eyes, and nose. Exposure to high levels of PM2.5 or even smaller particles in early childhood can cause asthma, and asthma attacks can then be triggered by exposure to PM10. While some parents or schools will keep asthmatic kids indoors on days when the PM levels are high, indoor air quality can often be just as bad or worse than outdoors. 

Cancer Alley already suffers from high levels of PM; for example, Koch Methanol’s proposed expansion would result in nearly 150 tons of PM released per year from its plant, and Nucor releases about 145 tons annually. Although petrochemical plants themselves release massive amounts of PM annually, another major source of PM pollution in Cancer Alley is from dock, port, terminal, and rail activities at those plants. 

The combination of high levels of PM in the air with other air pollutants in industrial areas is especially dangerous, since PM2.5 can form from or bind to metals and petrochemical pollution released into the atmosphere. Burning diesel as fuel releases a mix of incredibly small particles as well as carcinogenic chemicals; these two then bind together to make a PM that has been found to cause cancer in humans. 

PM is easy to detect using low-cost air monitors. A company called Purple Air sells PM air monitors for under $300, and the data is reported in real time to their website at map.purpleair.com. In 2022, a small network of Purple Air monitors established by Public Lab throughout St. James Parish was able to track spikes in pollution. 

PM is one of the criteria pollutants that EPA closely regulates for human health. In February of 2024, EPA announced that it was lowering the allowable levels of PM2.5 in ambient air, a measure that would save $77 in health related costs for every $1 spent on the program. EPA has also created the Clean Ports Program and Clean Heavy-Duty Vehicles Grant Program to reduce PM and other pollutants from diesel emissions in industrial areas. 

The new EPA-funded air monitor in the 5th District of St. James Parish tracks both PM2.5 and PM10. We hope that the parish, the state, and LDEQ can use this data to help improve the air quality for St. James Parish and beyond.

HOW TO REDUCE EXPOSURE TO PM POLLUTION

  • Install air purifiers in your home. Indoor air quality can sometimes be worse than outdoor!

  • Avoid exposure to diesel-burning engines.

  • Use the air quality index (AQI) published by LDEQ or weather websites to determine how long it is safe to be outside. You can see the AQI determined by the new air monitor in St. James Parish here: https://airquality.deq.louisiana.gov/Current/Site/STJAMES