diff --git a/homeassistant/components/london_air/sensor.py b/homeassistant/components/london_air/sensor.py
index c7104ac19ad..a8bebc20cf5 100644
--- a/homeassistant/components/london_air/sensor.py
+++ b/homeassistant/components/london_air/sensor.py
@@ -128,19 +128,21 @@ class AirSensor(Entity):
         """Return other details about the sensor state."""
         attrs = {}
         attrs["updated"] = self._updated
-        attrs["sites"] = len(self._site_data)
+        attrs["sites"] = len(self._site_data) if self._site_data is not None else 0
         attrs["data"] = self._site_data
         return attrs
 
     def update(self):
         """Update the sensor."""
-        self._api_data.update()
-        self._site_data = self._api_data.data[self._name]
-        self._updated = self._site_data[0]["updated"]
         sites_status = []
-        for site in self._site_data:
-            if site["pollutants_status"] != "no_species_data":
-                sites_status.append(site["pollutants_status"])
+        self._api_data.update()
+        if self._api_data.data:
+            self._site_data = self._api_data.data[self._name]
+            self._updated = self._site_data[0]["updated"]
+            for site in self._site_data:
+                if site["pollutants_status"] != "no_species_data":
+                    sites_status.append(site["pollutants_status"])
+
         if sites_status:
             self._state = max(set(sites_status), key=sites_status.count)
         else:
diff --git a/tests/components/london_air/test_sensor.py b/tests/components/london_air/test_sensor.py
index 066fc357a50..4ee28c54329 100644
--- a/tests/components/london_air/test_sensor.py
+++ b/tests/components/london_air/test_sensor.py
@@ -1,34 +1,51 @@
-"""The tests for the tube_state platform."""
-import unittest
-
-import requests_mock
-
+"""The tests for the london_air platform."""
 from homeassistant.components.london_air.sensor import CONF_LOCATIONS, URL
-from homeassistant.setup import setup_component
+from homeassistant.const import HTTP_OK, HTTP_SERVICE_UNAVAILABLE
+from homeassistant.setup import async_setup_component
 
-from tests.common import get_test_home_assistant, load_fixture
+from tests.common import load_fixture
 
-VALID_CONFIG = {"platform": "london_air", CONF_LOCATIONS: ["Merton"]}
+VALID_CONFIG = {"sensor": {"platform": "london_air", CONF_LOCATIONS: ["Merton"]}}
 
 
-class TestLondonAirSensor(unittest.TestCase):
-    """Test the tube_state platform."""
+async def test_valid_state(hass, requests_mock):
+    """Test for operational london_air sensor with proper attributes."""
+    requests_mock.get(URL, text=load_fixture("london_air.json"), status_code=HTTP_OK)
+    assert await async_setup_component(hass, "sensor", VALID_CONFIG)
+    await hass.async_block_till_done()
 
-    def setUp(self):
-        """Initialize values for this testcase class."""
-        self.hass = get_test_home_assistant()
-        self.config = VALID_CONFIG
-        self.addCleanup(self.hass.stop)
+    state = hass.states.get("sensor.merton")
+    assert state is not None
+    assert state.state == "Low"
+    assert state.attributes["icon"] == "mdi:cloud-outline"
+    assert state.attributes["updated"] == "2017-08-03 03:00:00"
+    assert state.attributes["sites"] == 2
+    assert state.attributes["friendly_name"] == "Merton"
 
-    @requests_mock.Mocker()
-    def test_setup(self, mock_req):
-        """Test for operational tube_state sensor with proper attributes."""
-        mock_req.get(URL, text=load_fixture("london_air.json"))
-        assert setup_component(self.hass, "sensor", {"sensor": self.config})
-        self.hass.block_till_done()
+    sites = state.attributes["data"]
+    assert sites is not None
+    assert len(sites) == 2
+    assert sites[0]["site_code"] == "ME2"
+    assert sites[0]["site_type"] == "Roadside"
+    assert sites[0]["site_name"] == "Merton Road"
+    assert sites[0]["pollutants_status"] == "Low"
 
-        state = self.hass.states.get("sensor.merton")
-        assert state.state == "Low"
-        assert state.attributes.get("updated") == "2017-08-03 03:00:00"
-        assert state.attributes.get("sites") == 2
-        assert state.attributes.get("data")[0]["site_code"] == "ME2"
+    pollutants = sites[0]["pollutants"]
+    assert pollutants is not None
+    assert len(pollutants) == 1
+    assert pollutants[0]["code"] == "PM10"
+    assert pollutants[0]["quality"] == "Low"
+    assert int(pollutants[0]["index"]) == 2
+    assert pollutants[0]["summary"] == "PM10 is Low"
+
+
+async def test_api_failure(hass, requests_mock):
+    """Test for failure in the API."""
+    requests_mock.get(URL, status_code=HTTP_SERVICE_UNAVAILABLE)
+    assert await async_setup_component(hass, "sensor", VALID_CONFIG)
+    await hass.async_block_till_done()
+
+    state = hass.states.get("sensor.merton")
+    assert state is not None
+    assert state.attributes["updated"] is None
+    assert state.attributes["sites"] == 0