Spatial and Statistical Analysis of High Risk Chloroprene Emissions in Laplace, Louisiana

Abstract

Objective: High concentrations of chloroprene, which is a monomer used to produce synthetic rubber and is classified as likely to be carcinogenic to humans, have been measured in the vicinity of the Denka Performance Elastomer facility in LaPlace, LA. New emission reduction projects were implemented by the company to reduce chloroprene emissions in 2018. This project explores the relationships between chloroprene concentrations and multiple geospatial and meteorological factors through spatial and statistical analyses. Methods: Multiple geospatial factors, including distance from the facility to monitoring sites and main roads and land use types around the monitoring sites and the facility, were determined by ArcGIS Pro. A chloroprene mapping tool was created to interpolate chloroprene levels based on ambient air monitoring data. Correlation tests and linear regression models were conducted to investigate correlations between chloroprene concentrations and meteorological factors, including wind speed and wind direction. Results: There is an inverse correlation between mean chloroprene concentration and distance from the facility to the monitoring sites. The land cover types around each monitoring site differ from each other and may influence the chloroprene concentrations. Wind speed was inversely correlated with chloroprene concentrations in five out of six monitoring sites, while temperature was also inversely correlated with chloroprene concentrations in two out of six sites. Wind direction also shows an effect on chloroprene concentration. The dominant wind directions are from the south and the east in LaPlace. Chloroprene concentrations tend to be higher at the monitoring sites to the west of the facility when the wind is blowing from the east, i.e., from the facility and toward a residential area. Chloroprene concentrations were statistically significantly decreased after the emission reduction projects were implemented. Conclusions: Even though there is a substantial decrease in chloroprene concentrations in the vicinity of the facility as a result of the emission reduction projects, mean chloroprene concentrations at the six monitoring sites still far exceed concentrations estimated to produce a 1 in 10,000 cancer risk by inhalation. It is recommended that Denka Performance Elastomer improve the effectiveness of their emission reduction projects and also consider limiting chloroprene emitting operations when meteorological factors such as low wind speed and winds from the east present a higher level of chloroprene concentrations in residential areas near the facility.