Chlorinated Paraffins in Global Air: First Results from the GAPS and GAPS-Megacities Networks

This study presents the first global data set of measured
chlorinated
paraffins (CPs), including short-chain (SCCPs), medium-chain (MCCPs),
and long-chain chlorinated paraffins (LCCPs) in ambient air, derived
from a single coordinated sampling network, i.e., the Global Atmospheric
Passive Sampling (GAPS) network, using a passive sampling approach.
Concentrations exhibited pronounced regional disparities, with the
combined levels in two megacitiesLagos, Nigeria (512,000 pg/m3) and Beijing, China (258,000 pg/m3) exceeding
by more than 1.5-fold the combined total levels observed across the
rest of the world (∼459,000 pg/m3). Evidence of
long-range atmospheric transport was observed at remote sites in western
Canada (Little Fox Lake and Whistler), influenced by trans-Pacific
air trajectories during the sampling period. These findings underscore
the substantial global heterogeneity in the spatial distribution of
CPs and the heavily disproportionate contributions of a few regions.
Notably, the major producers/emitters, such as China, had several
years of delay in ratifying the SCCP listing under the Stockholm Convention
(Annex A, elimination since 2017 for congeners with > 48% chlorine
content), and some countries have yet to ratify. Without the timely
implementation of regulatory measures in these jurisdictions, global
concentrations are expected to remain stagnant or even increase if
emissions persist at current levels. These results further suggest
that substantial time lags are likely before measurable declines in
SCCP concentrations, and potentially in recently listed MCCPs, are
observed even in regions where control measures are already in place.
Hence, this global data set serves as a baseline for future assessments
of temporal and spatial trends.