diff --git a/camdetect.py b/camdetect.py
index 1865b10..b571235 100755
--- a/camdetect.py
+++ b/camdetect.py
@@ -56,6 +56,9 @@ CLOCK_SKEW_TOLERANCE = timedelta(seconds=3)
 # Percentage of blocks active to consider movement in whole frame
 THRESHOLD_RATIO = int(os.getenv("THRESHOLD_RATIO", "5"))
 
+# Days to keep events
+TTL_DAYS = int(os.getenv("TTL_DAYS", "3"))
+
 CHUNK_BOUNDARY = b"\n--frame\nContent-Type: image/jpeg\n\n"
 
 hist_active_blocks_ratio = Histogram(
@@ -560,6 +563,8 @@ async def setup_db(app, loop):
     app.ctx.coll.create_index([
         ("source", pymongo.ASCENDING),
         ("@timestamp", pymongo.ASCENDING)], unique=True)
+    app.ctx.coll.create_index(
+        "@timestamp", expireAfterSeconds=TTL_DAYS*60*60*24)
     app.ctx.last_frame = None
     app.ctx.event_frame = asyncio.Event()
     app.ctx.event_id = None