From c9710c3d67738ad0d761ae8b8aacda20e6fffc84 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=20Kl=C3=ADma?= <tom.k@skaut.cz>
Date: Wed, 16 Oct 2019 14:34:48 +0200
Subject: [PATCH 1/2] added Air Pollution API

---
 Cmfcmf/OpenWeatherMap.php                  | 65 +++++++++++++++++-
 Cmfcmf/OpenWeatherMap/AirPollution.php     | 73 ++++++++++++++++++++
 Cmfcmf/OpenWeatherMap/AirPollutionData.php | 79 ++++++++++++++++++++++
 tests/OpenWeatherMapTest.php               | 11 +++
 4 files changed, 227 insertions(+), 1 deletion(-)
 create mode 100644 Cmfcmf/OpenWeatherMap/AirPollution.php
 create mode 100644 Cmfcmf/OpenWeatherMap/AirPollutionData.php

diff --git a/Cmfcmf/OpenWeatherMap.php b/Cmfcmf/OpenWeatherMap.php
index 1490280..9e73e64 100644
--- a/Cmfcmf/OpenWeatherMap.php
+++ b/Cmfcmf/OpenWeatherMap.php
@@ -18,10 +18,11 @@
 
 namespace Cmfcmf;
 
+use Cmfcmf\OpenWeatherMap\AirPollution;
 use Cmfcmf\OpenWeatherMap\CurrentWeather;
-use Cmfcmf\OpenWeatherMap\UVIndex;
 use Cmfcmf\OpenWeatherMap\CurrentWeatherGroup;
 use Cmfcmf\OpenWeatherMap\Exception as OWMException;
+use Cmfcmf\OpenWeatherMap\UVIndex;
 use Cmfcmf\OpenWeatherMap\WeatherForecast;
 use Psr\Cache\CacheItemPoolInterface;
 use Psr\Http\Client\ClientInterface;
@@ -67,6 +68,11 @@ class OpenWeatherMap
      */
     private $uvIndexUrl = 'https://api.openweathermap.org/data/2.5/uvi';
 
+    /**
+     * @var string The basic api url to fetch air pollution data from.
+     */
+    private $airPollutionUrl = 'https://api.openweathermap.org/pollution/v1/co';
+
     /**
      * @var CacheItemPoolInterface|null $cache The cache to use.
      */
@@ -336,6 +342,31 @@ public function getHistoricUVIndex($lat, $lon, $start, $end)
         }, $data);
     }
 
+    /**
+     * Returns atmosferic pollution by Carbon Monoxie
+     *
+     * @param float $lat The location's latitude.
+     * @param float $lon The location's longitude.
+     * @param ?DateTime|string $dateTime Time of the measurement. Set null for "current"
+     *
+     * @return AirPollution
+     *
+     * @api
+     * @throws \Exception
+     */
+    public function getAirPollution($lat, $lon, $dateTime = null)
+    {
+        if ($dateTime === null) {
+            $dateTime = 'current';
+        }
+
+        $answer = $this->getRawAirPollutionData($lat, $lon, $dateTime);
+        
+        $json = $this->parseJson($answer);
+
+        return new AirPollution($json);
+    }
+
     /**
      * Directly returns the xml/json/html string returned by OpenWeatherMap for the current weather.
      *
@@ -471,6 +502,20 @@ public function getRawUVIndexData($mode, $lat, $lon, $cnt = null, $start = null,
         return $this->cacheOrFetchResult($url);
     }
 
+    /**
+     * @param $lat
+     * @param $lon
+     * @param $dateTime
+     * @return bool|string Returns the fetched data.
+     * @throws OWMException
+     */
+    public function getRawAirPollutionData($lat, $lon, $dateTime)
+    {
+        $url = $this->buildAirPollutionUrl($lat, $lon, $dateTime, $this->airPollutionUrl);
+        
+        return $this->cacheOrFetchResult($url);
+    }
+
     /**
      * Returns whether or not the last result was fetched from the cache.
      *
@@ -505,6 +550,9 @@ private function cacheOrFetchResult($url)
         $response = $this->httpClient->sendRequest($this->httpRequestFactory->createRequest("GET", $url));
         $result = $response->getBody()->getContents();
         if ($response->getStatusCode() !== 200) {
+            if ($result === '{"message":"not found"}' && $response->getStatusCode() === 404) {
+                throw new OWMException('OpenWeatherMap returned that air pollution data for this location cannot be found - try less precision location.');
+            }
             throw new OWMException('OpenWeatherMap returned a response with status code ' . $response->getStatusCode() . ' and the following content '. $result);
         }
 
@@ -606,6 +654,21 @@ private function buildQueryUrlParameter($query)
         }
     }
 
+    /**
+     * Build the url to fetch air pollution data from.
+     *
+     * @param        $lat
+     * @param        $lon
+     * @param        $dateTime
+     * @param string $url The url to prepend.
+     *
+     * @return string The fetched url
+     */
+    private function buildAirPollutionUrl($lat, $lon, $dateTime, $url)
+    {
+        return $url."/$lat,$lon/$dateTime.json?appid=" . $this->apiKey;
+    }
+
     /**
      * @param string $answer The content returned by OpenWeatherMap.
      *
diff --git a/Cmfcmf/OpenWeatherMap/AirPollution.php b/Cmfcmf/OpenWeatherMap/AirPollution.php
new file mode 100644
index 0000000..8e24015
--- /dev/null
+++ b/Cmfcmf/OpenWeatherMap/AirPollution.php
@@ -0,0 +1,73 @@
+<?php
+
+/*
+ * OpenWeatherMap-PHP-API — A PHP API to parse weather data from https://OpenWeatherMap.org.
+ *
+ * @license MIT
+ *
+ * Please see the LICENSE file distributed with this source code for further
+ * information regarding copyright and licensing.
+ *
+ * Please visit the following links to read about the usage policies and the license of
+ * OpenWeatherMap data before using this library:
+ *
+ * @see https://OpenWeatherMap.org/price
+ * @see https://OpenWeatherMap.org/terms
+ * @see https://OpenWeatherMap.org/appid
+ */
+
+namespace Cmfcmf\OpenWeatherMap;
+
+use Cmfcmf\OpenWeatherMap\Util\Location;
+
+/**
+ * AirPollution class used to hold the air pollution and time of measurement
+ */
+class AirPollution
+{
+    /**
+     * @var \DateTime
+     */
+    public $dateTime;
+
+    /**
+     * @var Location
+     */
+    public $location;
+
+    /**
+     * @var AirPollutionData[]
+     */
+    public $data;
+
+    /**
+     * Create a new air pollution object.
+     *
+     * @param object $json
+     *
+     * @throws \Exception
+     * @internal
+     */
+    public function __construct($json)
+    {
+        $this->dateTime = new \DateTime($json->time, new \DateTimeZone('UTC'));
+        $this->location = new Location($json->location->latitude, $json->location->longitude);
+        $airPollutionData = [];
+        foreach ($json->data as $measurement) {
+            $airPollutionData[] = new AirPollutionData($measurement);
+        }
+        $this->data = $airPollutionData;
+    }
+
+    /**
+     * @return AirPollutionData|null
+     */
+    public function getLastAirPollutionData()
+    {
+        if (count($this->data) === 0) {
+            return null;
+        }
+
+        return reset($this->data);
+    }
+}
diff --git a/Cmfcmf/OpenWeatherMap/AirPollutionData.php b/Cmfcmf/OpenWeatherMap/AirPollutionData.php
new file mode 100644
index 0000000..9772cd6
--- /dev/null
+++ b/Cmfcmf/OpenWeatherMap/AirPollutionData.php
@@ -0,0 +1,79 @@
+<?php
+
+/*
+ * OpenWeatherMap-PHP-API — A PHP API to parse weather data from https://OpenWeatherMap.org.
+ *
+ * @license MIT
+ *
+ * Please see the LICENSE file distributed with this source code for further
+ * information regarding copyright and licensing.
+ *
+ * Please visit the following links to read about the usage policies and the license of
+ * OpenWeatherMap data before using this library:
+ *
+ * @see https://OpenWeatherMap.org/price
+ * @see https://OpenWeatherMap.org/terms
+ * @see https://OpenWeatherMap.org/appid
+ */
+
+namespace Cmfcmf\OpenWeatherMap;
+
+/**
+ * AirPollution class used to hold the air pollution and time of measurement
+ */
+class AirPollutionData
+{
+    /**
+     * @var float measurement precision
+     */
+    public $precision;
+
+    /**
+     * @var float atmospheric pressure at the point of measurement in hPa
+     */
+    public $pressure;
+
+    /**
+     * @var float volume mixing ratio
+     */
+    public $value;
+
+    /**
+     * Create a new air pollution data object.
+     *
+     * @param object $json
+     *
+     * @internal
+     */
+    public function __construct($json)
+    {
+        $this->precision = (float)$json->precision;
+        $this->pressure = (float)$json->pressure;
+        $this->value = (float)$json->value;
+    }
+
+    /**
+     * @return float
+     */
+    public function getPrecision(): float
+    {
+        return $this->precision;
+    }
+
+    /**
+     * @return float
+     */
+    public function getPressure(): float
+    {
+        return $this->pressure;
+    }
+
+    /**
+     * @return float
+     */
+    public function getValue(): float
+    {
+        return $this->value;
+    }
+    
+}
diff --git a/tests/OpenWeatherMapTest.php b/tests/OpenWeatherMapTest.php
index c5d3607..f816c38 100644
--- a/tests/OpenWeatherMapTest.php
+++ b/tests/OpenWeatherMapTest.php
@@ -167,6 +167,17 @@ public function testGetDailyWeatherForecast()
 
         $this->assertInstanceOf('\Cmfcmf\OpenWeatherMap\WeatherForecast', $dailyForecast);
     }
+    
+    public function testGetAirPollution() 
+    {
+        $airPollutionCurrent = $this->owm->getAirPollution(40, -74, null);
+        
+        $this->assertInstanceOf(OpenWeatherMap\AirPollution::class, $airPollutionCurrent);
+
+        $airPollutionPast = $this->owm->getAirPollution(40, -74, new \DateTime('now - 2 months'));
+        
+        $this->assertInstanceOf(OpenWeatherMap\AirPollution::class, $airPollutionPast);
+    }
 
     public function testWasCached()
     {

From 941af8d1b35e1c98368b46b77e68f72db469d2fc Mon Sep 17 00:00:00 2001
From: Christian Flach <cmfcmf.flach@gmail.com>
Date: Thu, 31 Oct 2019 20:11:41 +0100
Subject: [PATCH 2/2] Implement other air pollution apis

---
 Cmfcmf/OpenWeatherMap.php                     | 104 +++++++++++-------
 .../BaseAirPollution.php}                     |  35 +-----
 .../AirPollution/COAirPollution.php           |  23 ++++
 .../AirPollution/NO2AirPollution.php          |  49 +++++++++
 .../AirPollution/O3AirPollution.php           |  37 +++++++
 .../PrecisionPressureValueAirPollution.php    |  43 ++++++++
 .../AirPollution/SO2AirPollution.php          |  23 ++++
 Cmfcmf/OpenWeatherMap/AirPollutionData.php    |   1 -
 Cmfcmf/OpenWeatherMap/NotFoundException.php   |  26 +++++
 Cmfcmf/OpenWeatherMap/Util/Unit.php           |  23 +++-
 Examples/AirPollution.php                     |  81 ++++++++++++++
 README.md                                     |   1 +
 tests/FakeData.php                            |   4 +
 tests/OpenWeatherMapTest.php                  |  15 +--
 tests/TestHttpClient.php                      |   2 +
 15 files changed, 381 insertions(+), 86 deletions(-)
 rename Cmfcmf/OpenWeatherMap/{AirPollution.php => AirPollution/BaseAirPollution.php} (53%)
 create mode 100644 Cmfcmf/OpenWeatherMap/AirPollution/COAirPollution.php
 create mode 100644 Cmfcmf/OpenWeatherMap/AirPollution/NO2AirPollution.php
 create mode 100644 Cmfcmf/OpenWeatherMap/AirPollution/O3AirPollution.php
 create mode 100644 Cmfcmf/OpenWeatherMap/AirPollution/PrecisionPressureValueAirPollution.php
 create mode 100644 Cmfcmf/OpenWeatherMap/AirPollution/SO2AirPollution.php
 create mode 100644 Cmfcmf/OpenWeatherMap/NotFoundException.php
 create mode 100644 Examples/AirPollution.php

diff --git a/Cmfcmf/OpenWeatherMap.php b/Cmfcmf/OpenWeatherMap.php
index 9e73e64..7e21f4d 100644
--- a/Cmfcmf/OpenWeatherMap.php
+++ b/Cmfcmf/OpenWeatherMap.php
@@ -22,6 +22,7 @@
 use Cmfcmf\OpenWeatherMap\CurrentWeather;
 use Cmfcmf\OpenWeatherMap\CurrentWeatherGroup;
 use Cmfcmf\OpenWeatherMap\Exception as OWMException;
+use Cmfcmf\OpenWeatherMap\NotFoundException as OWMNotFoundException;
 use Cmfcmf\OpenWeatherMap\UVIndex;
 use Cmfcmf\OpenWeatherMap\WeatherForecast;
 use Psr\Cache\CacheItemPoolInterface;
@@ -71,7 +72,7 @@ class OpenWeatherMap
     /**
      * @var string The basic api url to fetch air pollution data from.
      */
-    private $airPollutionUrl = 'https://api.openweathermap.org/pollution/v1/co';
+    private $airPollutionUrl = 'https://api.openweathermap.org/pollution/v1/';
 
     /**
      * @var CacheItemPoolInterface|null $cache The cache to use.
@@ -343,28 +344,42 @@ public function getHistoricUVIndex($lat, $lon, $start, $end)
     }
 
     /**
-     * Returns atmosferic pollution by Carbon Monoxie
+     * Returns air pollution data
      *
-     * @param float $lat The location's latitude.
-     * @param float $lon The location's longitude.
-     * @param ?DateTime|string $dateTime Time of the measurement. Set null for "current"
+     * @param string $type One of CO, O3, SO2, and NO2.
+     * @param string $lat The location's latitude.
+     * @param string $lon The location's longitude.
+     * @param string $date The date to gather data from. If you omit this parameter or supply "current", returns current data.
+     *
+     * @return AirPollution\COAirPollution|AirPollution\NO2AirPollution|AirPollution\O3AirPollution|AirPollution\SO2AirPollution|null The air pollution data or null if no data was found.
+     *
+     * We use strings as $lat and $lon, since the exact number of digits in $lat and $lon determines the search range.
+     * For example, there is a difference between using "1.5" and "1.5000".
+     * We also use a string for $date, since it may either be "current" or an (abbreviated) ISO 8601 timestamp like 2016Z.
      *
-     * @return AirPollution
+     * @throws OWMException|\Exception
      *
      * @api
-     * @throws \Exception
      */
-    public function getAirPollution($lat, $lon, $dateTime = null)
+    public function getAirPollution($type, $lat, $lon, $date = "current")
     {
-        if ($dateTime === null) {
-            $dateTime = 'current';
+        $answer = $this->getRawAirPollutionData($type, $lat, $lon, $date);
+        if ($answer === null) {
+            return null;
         }
-
-        $answer = $this->getRawAirPollutionData($lat, $lon, $dateTime);
-        
         $json = $this->parseJson($answer);
-
-        return new AirPollution($json);
+        switch ($type) {
+            case "O3":
+                return new AirPollution\O3AirPollution($json);
+            case "NO2":
+                return new AirPollution\NO2AirPollution($json);
+            case "SO2":
+                return new AirPollution\SO2AirPollution($json);
+            case "CO":
+                return new AirPollution\COAirPollution($json);
+            default:
+                throw new \LogicException();
+        }
     }
 
     /**
@@ -503,17 +518,37 @@ public function getRawUVIndexData($mode, $lat, $lon, $cnt = null, $start = null,
     }
 
     /**
-     * @param $lat
-     * @param $lon
-     * @param $dateTime
-     * @return bool|string Returns the fetched data.
-     * @throws OWMException
+     * Fetch raw air pollution data
+     *
+     * @param  string $type One of CO, O3, SO2, and NO2.
+     * @param  string $lat  The location's latitude.
+     * @param  string $lon  The location's longitude.
+     * @param  string $date The date to gather data from. If you omit this parameter or supply "current", returns current data.
+     *
+     * @return string|null The air pollution data or null if no data was found.
+     *
+     * We use strings as $lat and $lon, since the exact number of digits in $lat and $lon determines the search range.
+     * For example, there is a difference between using "1.5" and "1.5000".
+     * We also use a string for $date, since it may either be "current" or an (abbreviated) ISO 8601 timestamp like 2016Z.
+     *
+     * @api
      */
-    public function getRawAirPollutionData($lat, $lon, $dateTime)
+    public function getRawAirPollutionData($type, $lat, $lon, $date = "current")
     {
-        $url = $this->buildAirPollutionUrl($lat, $lon, $dateTime, $this->airPollutionUrl);
-        
-        return $this->cacheOrFetchResult($url);
+        if (!in_array($type, ["CO", "O3", "SO2", "NO2"])) {
+            throw new \InvalidArgumentException('Invalid $type received.');
+        }
+        if (!is_string($lat) || !is_string($lon) || !is_string($date)) {
+            throw new \InvalidArgumentException('$lat, $lon and $date all must be strings.');
+        }
+
+        $url = $this->airPollutionUrl . strtolower($type) . "/$lat,$lon/$date.json?appid=" . $this->apiKey;
+
+        try {
+            return $this->cacheOrFetchResult($url);
+        } catch (OWMNotFoundException $e) {
+            return null;
+        }
     }
 
     /**
@@ -550,10 +585,10 @@ private function cacheOrFetchResult($url)
         $response = $this->httpClient->sendRequest($this->httpRequestFactory->createRequest("GET", $url));
         $result = $response->getBody()->getContents();
         if ($response->getStatusCode() !== 200) {
-            if ($result === '{"message":"not found"}' && $response->getStatusCode() === 404) {
-                throw new OWMException('OpenWeatherMap returned that air pollution data for this location cannot be found - try less precision location.');
+            if ($result === "{\"message\":\"not found\"}\n" && $response->getStatusCode() === 404) {
+                throw new OWMNotFoundException();
             }
-            throw new OWMException('OpenWeatherMap returned a response with status code ' . $response->getStatusCode() . ' and the following content '. $result);
+            throw new OWMException('OpenWeatherMap returned a response with status code ' . $response->getStatusCode() . ' and the following content `'. $result . '`');
         }
 
         if ($this->cache !== null) {
@@ -654,21 +689,6 @@ private function buildQueryUrlParameter($query)
         }
     }
 
-    /**
-     * Build the url to fetch air pollution data from.
-     *
-     * @param        $lat
-     * @param        $lon
-     * @param        $dateTime
-     * @param string $url The url to prepend.
-     *
-     * @return string The fetched url
-     */
-    private function buildAirPollutionUrl($lat, $lon, $dateTime, $url)
-    {
-        return $url."/$lat,$lon/$dateTime.json?appid=" . $this->apiKey;
-    }
-
     /**
      * @param string $answer The content returned by OpenWeatherMap.
      *
diff --git a/Cmfcmf/OpenWeatherMap/AirPollution.php b/Cmfcmf/OpenWeatherMap/AirPollution/BaseAirPollution.php
similarity index 53%
rename from Cmfcmf/OpenWeatherMap/AirPollution.php
rename to Cmfcmf/OpenWeatherMap/AirPollution/BaseAirPollution.php
index 8e24015..e9f4bd0 100644
--- a/Cmfcmf/OpenWeatherMap/AirPollution.php
+++ b/Cmfcmf/OpenWeatherMap/AirPollution/BaseAirPollution.php
@@ -16,19 +16,16 @@
  * @see https://OpenWeatherMap.org/appid
  */
 
-namespace Cmfcmf\OpenWeatherMap;
+namespace Cmfcmf\OpenWeatherMap\AirPollution;
 
 use Cmfcmf\OpenWeatherMap\Util\Location;
 
-/**
- * AirPollution class used to hold the air pollution and time of measurement
- */
-class AirPollution
+abstract class BaseAirPollution
 {
     /**
      * @var \DateTime
      */
-    public $dateTime;
+    public $time;
 
     /**
      * @var Location
@@ -36,13 +33,6 @@ class AirPollution
     public $location;
 
     /**
-     * @var AirPollutionData[]
-     */
-    public $data;
-
-    /**
-     * Create a new air pollution object.
-     *
      * @param object $json
      *
      * @throws \Exception
@@ -50,24 +40,7 @@ class AirPollution
      */
     public function __construct($json)
     {
-        $this->dateTime = new \DateTime($json->time, new \DateTimeZone('UTC'));
+        $this->time = new \DateTime($json->time, new \DateTimeZone('UTC'));
         $this->location = new Location($json->location->latitude, $json->location->longitude);
-        $airPollutionData = [];
-        foreach ($json->data as $measurement) {
-            $airPollutionData[] = new AirPollutionData($measurement);
-        }
-        $this->data = $airPollutionData;
-    }
-
-    /**
-     * @return AirPollutionData|null
-     */
-    public function getLastAirPollutionData()
-    {
-        if (count($this->data) === 0) {
-            return null;
-        }
-
-        return reset($this->data);
     }
 }
diff --git a/Cmfcmf/OpenWeatherMap/AirPollution/COAirPollution.php b/Cmfcmf/OpenWeatherMap/AirPollution/COAirPollution.php
new file mode 100644
index 0000000..b37e429
--- /dev/null
+++ b/Cmfcmf/OpenWeatherMap/AirPollution/COAirPollution.php
@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * OpenWeatherMap-PHP-API — A PHP API to parse weather data from https://OpenWeatherMap.org.
+ *
+ * @license MIT
+ *
+ * Please see the LICENSE file distributed with this source code for further
+ * information regarding copyright and licensing.
+ *
+ * Please visit the following links to read about the usage policies and the license of
+ * OpenWeatherMap data before using this library:
+ *
+ * @see https://OpenWeatherMap.org/price
+ * @see https://OpenWeatherMap.org/terms
+ * @see https://OpenWeatherMap.org/appid
+ */
+
+namespace Cmfcmf\OpenWeatherMap\AirPollution;
+
+class COAirPollution extends PrecisionPressureValueAirPollution
+{
+}
diff --git a/Cmfcmf/OpenWeatherMap/AirPollution/NO2AirPollution.php b/Cmfcmf/OpenWeatherMap/AirPollution/NO2AirPollution.php
new file mode 100644
index 0000000..fdfa8b3
--- /dev/null
+++ b/Cmfcmf/OpenWeatherMap/AirPollution/NO2AirPollution.php
@@ -0,0 +1,49 @@
+<?php
+
+/*
+ * OpenWeatherMap-PHP-API — A PHP API to parse weather data from https://OpenWeatherMap.org.
+ *
+ * @license MIT
+ *
+ * Please see the LICENSE file distributed with this source code for further
+ * information regarding copyright and licensing.
+ *
+ * Please visit the following links to read about the usage policies and the license of
+ * OpenWeatherMap data before using this library:
+ *
+ * @see https://OpenWeatherMap.org/price
+ * @see https://OpenWeatherMap.org/terms
+ * @see https://OpenWeatherMap.org/appid
+ */
+
+namespace Cmfcmf\OpenWeatherMap\AirPollution;
+
+use Cmfcmf\OpenWeatherMap\Util\Unit;
+
+class NO2AirPollution extends BaseAirPollution
+{
+
+    /**
+     * @var Unit
+     */
+    public $value;
+
+    /**
+     * @var Unit
+     */
+    public $valueStratosphere;
+
+    /**
+     * @var Unit
+     */
+    public $valueTroposphere;
+
+    public function __construct($json)
+    {
+        parent::__construct($json);
+
+        $this->value = new Unit($json->data->no2->value, "g/m³", "", $json->data->no2->precision);
+        $this->valueStratosphere = new Unit($json->data->no2_strat->value, "g/m³", "", $json->data->no2_strat->precision);
+        $this->valueTroposphere = new Unit($json->data->no2_trop->value, "g/m³", "", $json->data->no2_trop->precision);
+    }
+}
diff --git a/Cmfcmf/OpenWeatherMap/AirPollution/O3AirPollution.php b/Cmfcmf/OpenWeatherMap/AirPollution/O3AirPollution.php
new file mode 100644
index 0000000..c745903
--- /dev/null
+++ b/Cmfcmf/OpenWeatherMap/AirPollution/O3AirPollution.php
@@ -0,0 +1,37 @@
+<?php
+
+/*
+ * OpenWeatherMap-PHP-API — A PHP API to parse weather data from https://OpenWeatherMap.org.
+ *
+ * @license MIT
+ *
+ * Please see the LICENSE file distributed with this source code for further
+ * information regarding copyright and licensing.
+ *
+ * Please visit the following links to read about the usage policies and the license of
+ * OpenWeatherMap data before using this library:
+ *
+ * @see https://OpenWeatherMap.org/price
+ * @see https://OpenWeatherMap.org/terms
+ * @see https://OpenWeatherMap.org/appid
+ */
+
+namespace Cmfcmf\OpenWeatherMap\AirPollution;
+
+use Cmfcmf\OpenWeatherMap\Util\Unit;
+
+class O3AirPollution extends BaseAirPollution
+{
+
+    /**
+     * @var Unit
+     */
+    public $value;
+
+    public function __construct($json)
+    {
+        parent::__construct($json);
+
+        $this->value = new Unit($json->data, "DU");
+    }
+}
diff --git a/Cmfcmf/OpenWeatherMap/AirPollution/PrecisionPressureValueAirPollution.php b/Cmfcmf/OpenWeatherMap/AirPollution/PrecisionPressureValueAirPollution.php
new file mode 100644
index 0000000..ac4d246
--- /dev/null
+++ b/Cmfcmf/OpenWeatherMap/AirPollution/PrecisionPressureValueAirPollution.php
@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * OpenWeatherMap-PHP-API — A PHP API to parse weather data from https://OpenWeatherMap.org.
+ *
+ * @license MIT
+ *
+ * Please see the LICENSE file distributed with this source code for further
+ * information regarding copyright and licensing.
+ *
+ * Please visit the following links to read about the usage policies and the license of
+ * OpenWeatherMap data before using this library:
+ *
+ * @see https://OpenWeatherMap.org/price
+ * @see https://OpenWeatherMap.org/terms
+ * @see https://OpenWeatherMap.org/appid
+ */
+
+namespace Cmfcmf\OpenWeatherMap\AirPollution;
+
+use Cmfcmf\OpenWeatherMap\Util\Unit;
+
+class PrecisionPressureValueAirPollution extends BaseAirPollution
+{
+
+    /**
+     * @var object[]
+     */
+    public $values;
+
+    public function __construct($json)
+    {
+        parent::__construct($json);
+
+        $this->values = [];
+        foreach ($json->data as $data) {
+            $this->values[] = [
+                "value" => new Unit($data->value, "g/m³", "", $data->precision),
+                "pressure" => new Unit($data->pressure, "hPa"),
+            ];
+        }
+    }
+}
diff --git a/Cmfcmf/OpenWeatherMap/AirPollution/SO2AirPollution.php b/Cmfcmf/OpenWeatherMap/AirPollution/SO2AirPollution.php
new file mode 100644
index 0000000..aa7de23
--- /dev/null
+++ b/Cmfcmf/OpenWeatherMap/AirPollution/SO2AirPollution.php
@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * OpenWeatherMap-PHP-API — A PHP API to parse weather data from https://OpenWeatherMap.org.
+ *
+ * @license MIT
+ *
+ * Please see the LICENSE file distributed with this source code for further
+ * information regarding copyright and licensing.
+ *
+ * Please visit the following links to read about the usage policies and the license of
+ * OpenWeatherMap data before using this library:
+ *
+ * @see https://OpenWeatherMap.org/price
+ * @see https://OpenWeatherMap.org/terms
+ * @see https://OpenWeatherMap.org/appid
+ */
+
+namespace Cmfcmf\OpenWeatherMap\AirPollution;
+
+class SO2AirPollution extends PrecisionPressureValueAirPollution
+{
+}
diff --git a/Cmfcmf/OpenWeatherMap/AirPollutionData.php b/Cmfcmf/OpenWeatherMap/AirPollutionData.php
index 9772cd6..15cca86 100644
--- a/Cmfcmf/OpenWeatherMap/AirPollutionData.php
+++ b/Cmfcmf/OpenWeatherMap/AirPollutionData.php
@@ -75,5 +75,4 @@ public function getValue(): float
     {
         return $this->value;
     }
-    
 }
diff --git a/Cmfcmf/OpenWeatherMap/NotFoundException.php b/Cmfcmf/OpenWeatherMap/NotFoundException.php
new file mode 100644
index 0000000..b7fdbe6
--- /dev/null
+++ b/Cmfcmf/OpenWeatherMap/NotFoundException.php
@@ -0,0 +1,26 @@
+<?php
+
+/*
+ * OpenWeatherMap-PHP-API — A PHP API to parse weather data from https://OpenWeatherMap.org.
+ *
+ * @license MIT
+ *
+ * Please see the LICENSE file distributed with this source code for further
+ * information regarding copyright and licensing.
+ *
+ * Please visit the following links to read about the usage policies and the license of
+ * OpenWeatherMap data before using this library:
+ *
+ * @see https://OpenWeatherMap.org/price
+ * @see https://OpenWeatherMap.org/terms
+ * @see https://OpenWeatherMap.org/appid
+ */
+
+namespace Cmfcmf\OpenWeatherMap;
+
+/**
+ * @internal
+ */
+class NotFoundException extends Exception
+{
+}
diff --git a/Cmfcmf/OpenWeatherMap/Util/Unit.php b/Cmfcmf/OpenWeatherMap/Util/Unit.php
index 76652b2..9ad7a76 100644
--- a/Cmfcmf/OpenWeatherMap/Util/Unit.php
+++ b/Cmfcmf/OpenWeatherMap/Util/Unit.php
@@ -44,20 +44,27 @@ class Unit
      */
     private $description;
 
+    /**
+     * @var float|null The value's measurement precision. Can be null if unknown.
+     */
+    private $precision;
+
     /**
      * Create a new unit object.
      *
-     * @param float  $value       The value.
-     * @param string $unit        The unit of the value.
+     * @param float $value The value.
+     * @param string $unit The unit of the value.
      * @param string $description The description of the value.
+     * @param float|null $precision The precision of the value, or null if unknown.
      *
      * @internal
      */
-    public function __construct($value = 0.0, $unit = "", $description = "")
+    public function __construct($value = 0.0, $unit = "", $description = "", $precision = null)
     {
         $this->value = (float)$value;
         $this->unit = (string)$unit;
         $this->description = (string)$description;
+        $this->precision = $precision === null ? null : (float)$precision;
     }
 
     /**
@@ -112,6 +119,16 @@ public function getDescription()
         return $this->description;
     }
 
+    /**
+     * Get the value's precision.
+     *
+     * @return float|null The value's precision. Can be null if unknown.
+     */
+    public function getPrecision()
+    {
+        return $this->precision;
+    }
+
     /**
      * Get the value as formatted string with unit.
      *
diff --git a/Examples/AirPollution.php b/Examples/AirPollution.php
new file mode 100644
index 0000000..1ca9db5
--- /dev/null
+++ b/Examples/AirPollution.php
@@ -0,0 +1,81 @@
+<?php
+
+/*
+ * OpenWeatherMap-PHP-API — A PHP API to parse weather data from https://OpenWeatherMap.org.
+ *
+ * @license MIT
+ *
+ * Please see the LICENSE file distributed with this source code for further
+ * information regarding copyright and licensing.
+ *
+ * Please visit the following links to read about the usage policies and the license of
+ * OpenWeatherMap data before using this library:
+ *
+ * @see https://OpenWeatherMap.org/price
+ * @see https://OpenWeatherMap.org/terms
+ * @see https://OpenWeatherMap.org/appid
+ */
+
+use Cmfcmf\OpenWeatherMap;
+use Http\Factory\Guzzle\RequestFactory;
+use Http\Adapter\Guzzle6\Client as GuzzleAdapter;
+
+require_once __DIR__ . '/bootstrap.php';
+
+$cli = false;
+$lf = '<br>';
+if (php_sapi_name() === 'cli') {
+    $lf = "\n";
+    $cli = true;
+}
+
+// Language of data (try your own language here!):
+$lang = 'de';
+
+// Units (can be 'metric' or 'imperial' [default]):
+$units = 'metric';
+
+// You can use every PSR-17 compatible HTTP request factory
+// and every PSR-18 compatible HTTP client.
+$httpRequestFactory = new RequestFactory();
+$httpClient = GuzzleAdapter::createWithConfig([]);
+
+$owm = new OpenWeatherMap($myApiKey, $httpClient, $httpRequestFactory);
+
+// Example 1: Get current uv index in Berlin.
+$o3 = $owm->getAirPollution("O3", "52", "13");
+$no2 = $owm->getAirPollution("NO2", "52", "13");
+$so2 = $owm->getAirPollution("SO2", "52", "13");
+$co = $owm->getAirPollution("CO", "52", "13");
+
+echo "O3: ";
+if ($o3 === null) {
+    echo "no data" . $lf;
+} else {
+    echo $o3->value . $lf;
+}
+
+echo "NO2: ";
+if ($no2 === null) {
+    echo "no data" . $lf;
+} else {
+    echo $no2->value;
+}
+
+echo "SO2: ";
+if ($so2 === null) {
+    echo "no data" . $lf;
+} else {
+    foreach ($so2->values as $data) {
+        echo "value: " . $data["value"] . " (precision: " . $data["value"]->getPrecision() . ", pressure: " . $data["pressure"] . ")" . $lf;
+    }
+}
+
+echo "CO: ";
+if ($co === null) {
+    echo "no data" . $lf;
+} else {
+    foreach ($co->values as $data) {
+        echo "value: " . $data["value"] . " (precision: " . $data["value"]->getPrecision() . ", pressure: " . $data["pressure"] . ")" . $lf;
+    }
+}
diff --git a/README.md b/README.md
index a8c6c37..e8cbae9 100644
--- a/README.md
+++ b/README.md
@@ -75,6 +75,7 @@ http://home.openweathermap.org/ and put it into `Examples/ApiKey.ini`.
 - `CurrentWeather.php` shows how to receive the current weather.
 - `WeatherForecast.php` shows how to receive weather forecasts.
 - `UVIndex.php` shows how to receive uv index data.
+- `AirPollution.php` show how to receive air pollution data.
 
 Contributing
 ============
diff --git a/tests/FakeData.php b/tests/FakeData.php
index c7aa35c..3d090c4 100644
--- a/tests/FakeData.php
+++ b/tests/FakeData.php
@@ -127,4 +127,8 @@ public static function forecastXML()
     <lastupdate value="2017-01-02T12:20:00"></lastupdate>
 </current>
 XML;
+
+    const AIR_POLLUTION_CO = <<<JSON
+{"time":"2019-10-26T18:15:01Z","location":{"latitude":40.0013,"longitude":-74.5899},"data":[{"precision":-4.999999987376214e-07,"pressure":1000,"value":1.3621800576402165e-07},{"precision":-4.999999987376214e-07,"pressure":681.2920532226562,"value":1.1375255581924648e-07},{"precision":-4.999999987376214e-07,"pressure":464.15887451171875,"value":1.038646146866995e-07},{"precision":4.547785792397008e-08,"pressure":316.2277526855469,"value":1.7132454388502083e-07},{"precision":2.0379493648192692e-08,"pressure":215.44346618652344,"value":1.1696990753762293e-07},{"precision":1.3544046773006357e-08,"pressure":146.77992248535156,"value":6.227620730214767e-08},{"precision":1.1640130637147195e-08,"pressure":100,"value":4.9975231064536274e-08},{"precision":1.0211765655299132e-08,"pressure":68.12920379638672,"value":5.12039584066315e-08},{"precision":8.732828682411764e-09,"pressure":46.415889739990234,"value":3.545491722434235e-08},{"precision":9.014621049630023e-09,"pressure":31.62277603149414,"value":1.8382916522341475e-08},{"precision":9.907536124842409e-09,"pressure":21.544347763061523,"value":1.8576894467159377e-09},{"precision":1.2424509421293806e-08,"pressure":14.677992820739746,"value":-9.168636516676543e-09},{"precision":1.5284239651691678e-08,"pressure":10,"value":2.2812981725905956e-08},{"precision":2.1570169650431126e-08,"pressure":6.812920570373535,"value":5.2754966617385435e-08},{"precision":2.913583330155234e-08,"pressure":4.6415886878967285,"value":6.849927558505442e-08},{"precision":3.875063470104578e-08,"pressure":3.1622776985168457,"value":-1.6690947290953773e-08},{"precision":5.409619419083356e-08,"pressure":2.1544346809387207,"value":-2.6772934091923162e-08},{"precision":7.21046475860021e-08,"pressure":1.4677993059158325,"value":1.0366177605192206e-07},{"precision":9.633781417051068e-08,"pressure":1,"value":4.523308305692808e-08},{"precision":1.4515163115902396e-07,"pressure":0.6812920570373535,"value":7.092549481058086e-08},{"precision":2.062685240389328e-07,"pressure":0.46415889263153076,"value":6.615503878037998e-08},{"precision":2.907468115154188e-07,"pressure":0.3162277638912201,"value":-3.38239033226273e-07},{"precision":4.297635598504712e-07,"pressure":0.2154434621334076,"value":1.6955895034698187e-06},{"precision":6.078225851524621e-07,"pressure":0.14677992463111877,"value":2.2467602889264526e-07},{"precision":6.833994916632946e-07,"pressure":0.10000000149011612,"value":7.392927159344254e-07},{"precision":1.017242993839318e-06,"pressure":0.04641588777303696,"value":2.740956688285223e-06},{"precision":1.8878859009419102e-06,"pressure":0.02154434658586979,"value":2.360790404054569e-06},{"precision":3.784052296396112e-06,"pressure":0.009999999776482582,"value":8.210285159293562e-06},{"precision":6.664358807029203e-06,"pressure":0.004641588777303696,"value":1.6543688616366126e-05},{"precision":-1.0293148989148904e-05,"pressure":0.002154434798285365,"value":4.2166899220319465e-05},{"precision":-1.5317784345825203e-05,"pressure":0.0010000000474974513,"value":4.3754778744187206e-05},{"precision":-1.9999999494757503e-05,"pressure":0.00046415888937190175,"value":1.658740802668035e-05},{"precision":-1.9999999494757503e-05,"pressure":0.00021544346236623824,"value":1.658740802668035e-05},{"precision":-1.9999999494757503e-05,"pressure":9.999999747378752e-05,"value":1.658740802668035e-05},{"precision":-1.9999999494757503e-05,"pressure":4.641588748199865e-05,"value":1.658740802668035e-05},{"precision":-1.9999999494757503e-05,"pressure":2.1544346964219585e-05,"value":1.658740802668035e-05},{"precision":-1.9999999494757503e-05,"pressure":9.999999747378752e-06,"value":1.658740802668035e-05}]}
+JSON;
 }
diff --git a/tests/OpenWeatherMapTest.php b/tests/OpenWeatherMapTest.php
index f816c38..bf4f173 100644
--- a/tests/OpenWeatherMapTest.php
+++ b/tests/OpenWeatherMapTest.php
@@ -167,16 +167,13 @@ public function testGetDailyWeatherForecast()
 
         $this->assertInstanceOf('\Cmfcmf\OpenWeatherMap\WeatherForecast', $dailyForecast);
     }
-    
-    public function testGetAirPollution() 
-    {
-        $airPollutionCurrent = $this->owm->getAirPollution(40, -74, null);
-        
-        $this->assertInstanceOf(OpenWeatherMap\AirPollution::class, $airPollutionCurrent);
 
-        $airPollutionPast = $this->owm->getAirPollution(40, -74, new \DateTime('now - 2 months'));
-        
-        $this->assertInstanceOf(OpenWeatherMap\AirPollution::class, $airPollutionPast);
+    public function testGetAirPollution()
+    {
+        $airPollutionCurrent = $this->owm->getAirPollution("CO", "40", "-74", "current");
+        $this->assertInstanceOf(OpenWeatherMap\AirPollution\COAirPollution::class, $airPollutionCurrent);
+        $airPollutionPast = $this->owm->getAirPollution("CO", "40", "-74", "2016Z");
+        $this->assertInstanceOf(OpenWeatherMap\AirPollution\COAirPollution::class, $airPollutionPast);
     }
 
     public function testWasCached()
diff --git a/tests/TestHttpClient.php b/tests/TestHttpClient.php
index 7e5fea3..253598c 100644
--- a/tests/TestHttpClient.php
+++ b/tests/TestHttpClient.php
@@ -51,6 +51,8 @@ public function sendRequest(RequestInterface $request): ResponseInterface
             $content = $this->forecast($format);
         } elseif (strpos($url, 'group') !== false) {
             $content = $this->group($format);
+        } elseif (strpos($url, "pollution") !== false) {
+            $content = FakeData::AIR_POLLUTION_CO;
         } else {
             $content = $this->currentWeather($format);
         }