diff --git a/src/sp2xr/calibration.py b/src/sp2xr/calibration.py
index b64deb0..a47f76d 100644
--- a/src/sp2xr/calibration.py
+++ b/src/sp2xr/calibration.py
@@ -228,14 +228,20 @@ def calibrate_single_particle(
     )
     ddf_cal["time_lag"] = ddf_cal["Incand Peak Time"] - ddf_cal["Scatter Peak Time"]
 
-    # Suppress divide by zero warning for log10(0) - expected for particles with no signal
-    import warnings
+    # Calculate ratio using map_partitions to properly suppress warnings in Dask workers
+    def calculate_ratio_with_suppression(df):
+        """Calculate log10 ratio with warning suppression for zero values."""
+        with np.errstate(divide="ignore", invalid="ignore"):
+            df["ratio_inc_scatt"] = np.log10(df["Incand relPeak"]) / np.log10(
+                df["Scatter relPeak"]
+            )
+        return df
 
-    with warnings.catch_warnings():
-        warnings.filterwarnings("ignore", message="divide by zero encountered in log10")
-        ddf_cal["ratio_inc_scatt"] = np.log10(ddf_cal["Incand relPeak"]) / np.log10(
-            ddf_cal["Scatter relPeak"]
-        )
+    meta_with_ratio = ddf_cal._meta.copy()
+    meta_with_ratio["ratio_inc_scatt"] = pd.Series([], dtype="float64")
+    ddf_cal = ddf_cal.map_partitions(
+        calculate_ratio_with_suppression, meta=meta_with_ratio
+    )
 
     ddf_cal = define_flags(ddf_cal, instr_config, run_config)