diff --git a/README.md b/README.md
index 349e915..3200042 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,7 @@ Optional environment variables:
 * `EXTERNAL_PROTOCOL` - typically http when running locally, can be https when deployed if the gateway is behind a load balancer or reverse proxy that performs https termination. Default value "http"
 * `GATEWAY_IP` - ip addess of instance gateway is running on, mostly used to display SSH instructions. Defaults to `socket.gethostbyname(socket.gethostname())`
 * `GATEWAY_PORT` - local port that the gateway should bind to, defaults to 5005
+* `GATEWAY_EXPIRE_SECONDS` - time in seconds that a cellxgene process will remain idle before being terminated. Defaults to 3600 (one hour)
 * `GATEWAY_EXTRA_SCRIPTS` - JSON array of script paths, will be embedded into each page and forwarded with `--scripts` to cellxgene server
 * `GATEWAY_ENABLE_ANNOTATIONS` - Set to `true` or to `1` to enable cellxgene annotations. 
 * `GATEWAY_ENABLE_BACKED_MODE` - Set to `true` or to `1` to load AnnData in file-backed mode. This saves memory and speeds up launch time but may reduce overall performance.
diff --git a/cellxgene_gateway/env.py b/cellxgene_gateway/env.py
index 26288c4..5cf0c1b 100644
--- a/cellxgene_gateway/env.py
+++ b/cellxgene_gateway/env.py
@@ -23,7 +23,9 @@ external_protocol = os.environ.get(
 )
 ip = os.environ.get("GATEWAY_IP")
 extra_scripts = os.environ.get("GATEWAY_EXTRA_SCRIPTS")
-ttl = os.environ.get("GATEWAY_TTL")
+expire_seconds = int(
+    os.environ.get("GATEWAY_EXPIRE_SECONDS", os.environ.get("GATEWAY_TTL", "3600"))
+)
 enable_annotations = os.environ.get("GATEWAY_ENABLE_ANNOTATIONS", "").lower() in [
     "true",
     "1",
@@ -50,7 +52,7 @@ optional_env_vars = {
     "GATEWAY_IP": ip,
     "GATEWAY_PORT": gateway_port,
     "GATEWAY_EXTRA_SCRIPTS": extra_scripts,
-    "GATEWAY_TTL": ttl,
+    "GATEWAY_EXPIRE_SECONDS": expire_seconds,
     "GATEWAY_ENABLE_ANNOTATIONS": enable_annotations,
     "GATEWAY_ENABLE_BACKED_MODE": enable_backed_mode,
     "GATEWAY_LOG_LEVEL": log_level,
diff --git a/cellxgene_gateway/prune_process_cache.py b/cellxgene_gateway/prune_process_cache.py
index 29eafb4..b22b80e 100644
--- a/cellxgene_gateway/prune_process_cache.py
+++ b/cellxgene_gateway/prune_process_cache.py
@@ -18,7 +18,7 @@ logger = logging.getLogger(__name__)
 class PruneProcessCache:
     def __init__(self, cache):
         self.cache = cache
-        self.expire_seconds = 3600 if env.ttl is None else int(env.ttl)
+        self.expire_seconds = env.expire_seconds
 
     def __call__(self):
         while True:
diff --git a/tests/test_prune_process_cache.py b/tests/test_prune_process_cache.py
index b500007..00b9321 100644
--- a/tests/test_prune_process_cache.py
+++ b/tests/test_prune_process_cache.py
@@ -15,7 +15,7 @@ key = CacheKey(
 
 class TestPruneProcessCache(unittest.TestCase):
     @patch("cellxgene_gateway.util.current_time_stamp", new=lambda: 0)
-    @patch("cellxgene_gateway.env.ttl", new="10")
+    @patch("cellxgene_gateway.env.expire_seconds", new=10)
     @patch("cellxgene_gateway.cache_entry.CacheEntry")
     @patch("cellxgene_gateway.cache_entry.CacheEntry")
     def test_GIVEN_one_old_one_new_THEN_prune_old(self, old, new):