diff --git a/sumo_project/SUMOFactory.py b/sumo_project/SUMOFactory.py
index 8f529db..80c9444 100644
--- a/sumo_project/SUMOFactory.py
+++ b/sumo_project/SUMOFactory.py
@@ -14,10 +14,9 @@ class SUMOFactory(object):
         traci.vehicle.remove(veh_id, traci.constants.REMOVE_PARKING)
 
     def lanes_in_area(self, area):
-        polygon_area = area.rectangle
         for lane_id in traci.lane.getIDList():
             polygon_lane = LineString(traci.lane.getShape(lane_id))
-            if polygon_area.intersects(polygon_lane):
+            if area.rectangle.intersects(polygon_lane):
                 yield lane_id
            
     def lock_area(self, area):
diff --git a/sumo_project/area.py b/sumo_project/area.py
index 7f41202..b552aee 100644
--- a/sumo_project/area.py
+++ b/sumo_project/area.py
@@ -12,13 +12,13 @@ class Area:
     def __eq__(self, other):
         return self.rectangle.__eq__(other)
 
+    def __contains__(self, item):
+        return self.rectangle.contains(Point(item))
+
     @property
     def bounds(self):
         return self.rectangle.bounds
 
-    def contains(self, other):
-        return self.rectangle.contains(Point(other))
-
     @classmethod
     def from_bounds(cls, xmin, ymin, xmax, ymax):
         return cls((
diff --git a/sumo_project/emissions.py b/sumo_project/emissions.py
index 7766ade..276dbb8 100644
--- a/sumo_project/emissions.py
+++ b/sumo_project/emissions.py
@@ -26,7 +26,7 @@ def emission_for_area(area):
     # retrieve all vehicles into this area
     for veh_id in traci.vehicle.getIDList():
         pos = traci.vehicle.getPosition(veh_id)
-        if area.contains(pos):
+        if pos in area:
             area.emissions += traci.vehicle.getCO2Emission(veh_id)