diff --git a/.github/workflows/coding-standard.yml b/.github/workflows/coding-standard.yml
index ecb82bf..ccd5f45 100644
--- a/.github/workflows/coding-standard.yml
+++ b/.github/workflows/coding-standard.yml
@@ -11,8 +11,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        operating-system: [ ubuntu-latest, windows-latest, macOS-latest ]
-        php-versions: [ '8.0', '8.1', '8.2' ]
+        operating-system: [ubuntu-latest, windows-latest, macOS-latest]
+        php-versions: ["8.2", "8.3"]
 
     steps:
       - name: Set git to use LF
@@ -21,9 +21,7 @@ jobs:
           git config --global core.eol lf
 
       - name: Checkout
-        uses: actions/checkout@v2.3.4
-        with:
-          fetch-depth: 1
+        uses: actions/checkout@v3
 
       - name: Install PHP
         uses: shivammathur/setup-php@v2
@@ -36,7 +34,7 @@ jobs:
         run: echo "::set-output name=dir::$(composer config cache-files-dir)"
 
       - name: Cache Composer dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: ${{ steps.composer-cache.outputs.dir }}
           key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
diff --git a/.github/workflows/mutation-tests.yml b/.github/workflows/mutation-tests.yml
index 45bb3ba..5df8b8b 100644
--- a/.github/workflows/mutation-tests.yml
+++ b/.github/workflows/mutation-tests.yml
@@ -11,8 +11,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        operating-system: [ ubuntu-latest ]
-        php-versions: [ '8.0', '8.1', '8.2' ]
+        operating-system: [ubuntu-latest]
+        php-versions: ["8.2", "8.3"]
 
     steps:
       - name: Set git to use LF
@@ -21,9 +21,7 @@ jobs:
           git config --global core.eol lf
 
       - name: Checkout
-        uses: actions/checkout@v2.3.4
-        with:
-          fetch-depth: 1
+        uses: actions/checkout@v3
 
       - name: Install PHP
         uses: shivammathur/setup-php@v2
@@ -36,7 +34,7 @@ jobs:
         run: echo "::set-output name=dir::$(composer config cache-files-dir)"
 
       - name: Cache Composer dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: ${{ steps.composer-cache.outputs.dir }}
           key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
diff --git a/.github/workflows/stale.yml b/.github/workflows/stale.yml
index 93f0cd0..710271f 100644
--- a/.github/workflows/stale.yml
+++ b/.github/workflows/stale.yml
@@ -10,7 +10,6 @@ env:
 
 jobs:
   stale:
-
     runs-on: "ubuntu-latest"
 
     steps:
diff --git a/.github/workflows/static-analysis.yml b/.github/workflows/static-analysis.yml
index 62f0c14..b280b6c 100644
--- a/.github/workflows/static-analysis.yml
+++ b/.github/workflows/static-analysis.yml
@@ -11,8 +11,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        operating-system: [ ubuntu-latest, windows-latest, macOS-latest ]
-        php-versions: ['8.0', '8.1', '8.2' ]
+        operating-system: [ubuntu-latest, windows-latest, macOS-latest]
+        php-versions: ["8.2", "8.3"]
 
     steps:
       - name: Set git to use LF
@@ -21,9 +21,7 @@ jobs:
           git config --global core.eol lf
 
       - name: Checkout
-        uses: actions/checkout@v2.3.4
-        with:
-          fetch-depth: 1
+        uses: actions/checkout@v3
 
       - name: Install PHP
         uses: shivammathur/setup-php@v2
@@ -36,7 +34,7 @@ jobs:
         run: echo "::set-output name=dir::$(composer config cache-files-dir)"
 
       - name: Cache Composer dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: ${{ steps.composer-cache.outputs.dir }}
           key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index fc5f94c..08403c3 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -11,8 +11,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        operating-system: [ ubuntu-latest, windows-latest, macOS-latest ]
-        php-versions: [ '8.0', '8.1', '8.2' ]
+        operating-system: [ubuntu-latest, windows-latest, macOS-latest]
+        php-versions: ["8.2", "8.3"]
 
     steps:
       - name: Set git to use LF
@@ -21,9 +21,7 @@ jobs:
           git config --global core.eol lf
 
       - name: Checkout
-        uses: actions/checkout@v2.3.4
-        with:
-          fetch-depth: 1
+        uses: actions/checkout@v3
 
       - name: Install PHP
         uses: shivammathur/setup-php@v2
@@ -36,7 +34,7 @@ jobs:
         run: echo "::set-output name=dir::$(composer config cache-files-dir)"
 
       - name: Cache Composer dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: ${{ steps.composer-cache.outputs.dir }}
           key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
diff --git a/.gitignore b/.gitignore
index 9aeb980..09b36b9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 .idea/
 .php-cs-fixer.cache
+.phpactor.json
 .phpunit.cache
 .phpunit.result.cache
 composer.lock
diff --git a/.phan/config.php b/.phan/config.php
index 6e546fd..e791ec6 100644
--- a/.phan/config.php
+++ b/.phan/config.php
@@ -51,7 +51,7 @@
     // Note that the **only** effect of choosing `'5.6'` is to infer that functions removed in php 7.0 exist.
     // (See `backward_compatibility_checks` for additional options)
     // Automatically inferred from composer.json requirement for "php" of "^7.4 || ^8.0"
-    'target_php_version' => '8.0',
+    'target_php_version' => '8.2',
 
     // If enabled, missing properties will be created when
     // they are first seen. If false, we'll report an
diff --git a/.php-cs-fixer.dist.php b/.php-cs-fixer.dist.php
new file mode 100644
index 0000000..2f04070
--- /dev/null
+++ b/.php-cs-fixer.dist.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * This file is part of the WAQI (World Air Quality Index) package.
+ *
+ * Copyright (c) 2017 - 2024 AzuyaLabs
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * @author Sacha Telgenhof <me at sachatelgenhof dot com>
+ */
+
+$finder = PhpCsFixer\Finder::create()->in(__DIR__)->notPath('var');
+
+$config = new PhpCsFixer\Config();
+$config->setRiskyAllowed(true)->setRules([
+  '@Symfony' => true,
+  '@PER' => true,
+  'combine_consecutive_issets' => true,
+  'combine_consecutive_unsets' => true,
+  'ordered_class_elements' => true,
+  'no_superfluous_elseif' => true,
+  'no_superfluous_phpdoc_tags' => ['remove_inheritdoc' => true],
+  'not_operator_with_successor_space' => true,
+
+  // Risky
+  'declare_strict_types' => true,
+  'dir_constant' => true,
+  'get_class_to_class_keyword' => true,
+  'is_null' => true,
+  'modernize_strpos' => true,
+  'modernize_types_casting' => true,
+  'native_constant_invocation' => ['strict' => false],
+  'self_accessor' => true,
+])->setFinder($finder);
+
+return $config;
diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
deleted file mode 100644
index b6fec6f..0000000
--- a/.php-cs-fixer.php
+++ /dev/null
@@ -1,32 +0,0 @@
-<?php
-
-declare(strict_types=1);
-/**
- * This file is part of the WAQI (World Air Quality Index) package.
- *
- * Copyright (c) 2017 - 2023 AzuyaLabs
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- *
- * @author Sacha Telgenhof <me at sachatelgenhof dot com>
- */
-
-$finder = PhpCsFixer\Finder::create()->in(__DIR__)->notPath('var');
-
-$config = new PhpCsFixer\Config();
-$config->setRiskyAllowed(true)->setRules([
-    '@Symfony' => true,
-    'blank_line_after_opening_tag' => true,
-    'is_null' => true,
-    'modernize_types_casting' => true,
-    'self_accessor' => true,
-    'dir_constant' => true,
-    'ordered_class_elements' => true,
-    'declare_strict_types' => true,
-    'no_superfluous_elseif' => true,
-    'combine_consecutive_issets' => true,
-    'combine_consecutive_unsets' => true,
-])->setFinder($finder);
-
-return $config;
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 26f0c90..ab3b90e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,9 +1,9 @@
-# Change Log
+# Changelog
 
 All notable changes to this project will be documented in this file.
 
-The format is based on [Keep a Changelog](http://keepachangelog.com/) and this project adheres
-to [Semantic Versioning](http://semver.org).
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
@@ -15,6 +15,22 @@ to [Semantic Versioning](http://semver.org).
 
 ### Removed
 
+## [1.2.1] - 2024-01-03
+
+### Added
+
+- PHP 8.3 Support.
+
+### Changed
+
+- Updated copyright year.
+- Simplify the code making it more concise and readable.
+- Refactor code for improved readability and consistency.
+
+### Removed
+
+- PHP 8.1 Support.
+
 ## [1.2.0] 2023-02-23
 
 ### Added
@@ -88,7 +104,7 @@ to [Semantic Versioning](http://semver.org).
   monitoring station doesn't measure these.
 - Minimum requirement for PHP to 7.1.0
 - Updated package versions for PHPStan, Mockery and PHPUnit.
-- Updated inline documentation (various).
+- Updated in-line documentation (various).
 
 ### Fixed
 
@@ -97,18 +113,15 @@ to [Semantic Versioning](http://semver.org).
 ### Removed
 
 - Removed type casting as variables are already of proper data type.
-- Removed invalid syntaxCheck parameter from the PHPUnit XML configuration.
+- Removed invalid `syntaxCheck` parameter from the PHPUnit XML configuration.
 
 ## [1.0.0] 2017-02-15
 
 - Initial release
 
-[Unreleased]: https://github.com/azuyalabs/waqi/compare/1.2.0...HEAD
-
+[Unreleased]: https://github.com/azuyalabs/waqi/compare/1.2.1...HEAD
+[1.2.1]: https://github.com/azuyalabs/waqi/compare/1.2.0...1.2.1
 [1.2.0]: https://github.com/azuyalabs/waqi/compare/1.1.0...1.2.0
-
 [1.1.0]: https://github.com/azuyalabs/waqi/compare/1.0.1...1.1.0
-
 [1.0.1]: https://github.com/azuyalabs/waqi/compare/1.0.0...1.0.1
-
 [1.0.0]: https://github.com/azuyalabs/waqi/releases/tag/1.0.0
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 1037943..2e2b552 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -10,8 +10,8 @@ When contributing there are a few guidelines I would like you to keep in mind:
 - **[PSR-12 Coding Standard](https://www.php-fig.org/psr/psr-12/)**
   Please use the following command after you have completed your work:
 
-  ``` bash
-  $ composer format
+  ```shell
+  composer format
   ```
 
   This will check/correct all the code for the PSR-12 Coding Standard using the
@@ -31,12 +31,12 @@ When contributing there are a few guidelines I would like you to keep in mind:
 
 ## Running Tests
 
-``` bash
-$ composer test
+```shell
+composer test
 ```
 
-or alternatively run with:
+,or alternatively run with:
 
-``` bash
-$ vendor/bin/phpunit
+```shell
+vendor/bin/phpunit
 ```
diff --git a/LICENSE b/LICENSE
index e927677..6dc9f4f 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2017 - 2023 AzuyaLabs
+Copyright (c) 2017 - 2024 AzuyaLabs
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/README.md b/README.md
index 85c73f5..f7721a0 100644
--- a/README.md
+++ b/README.md
@@ -12,23 +12,23 @@ This packages makes it easy to retrieve the Air Quality Index for your area and
 data feed (API) of the WAQI project.
 
 Note: To make use of this package (and the underlying AQI API) an access token is required. You can acquire your token
-here: https://aqicn.org/data-platform/token.
+here: [https://aqicn.org/data-platform/token.](https://aqicn.org/data-platform/tokeni).
 
 ## System Requirements
 
-You need *PHP >= 8.0* to use 'azuyalabs/waqi'.
+You need _PHP >= 8.2_ to use `azuyalabs/waqi`.
 
 ## Installation
 
 You can pull in this package via composer:
 
-``` bash
-$ composer require azuyalabs/waqi
+```shell
+composer require azuyalabs/waqi
 ```
 
 ## Usage
 
-Start with including the Composer autoload file in your project:
+Start with including the Composer `autoload` file in your project:
 
 ```php
 <?php
@@ -71,7 +71,7 @@ measurement. It contains 4 elements:
 
 Example output (for 'New York'):
 
-```
+```shell
  - 'aqi': 15
  - 'pollution_level': Good
  - 'health_implications': Air quality is considered satisfactory, and air pollution poses little or no risk.
@@ -109,7 +109,7 @@ Secondly, the API method `getAttributions()` will return a list of EPA attributi
 
 Other API methods that provide additional information, are:
 
-- `getMeasurementTime()`: returns the date/time the last measurement was taken. (as a DateTime object).
+- `getMeasurementTime()`: returns the date/time the last measurement was taken. (as a `DateTime` object).
 - `getHumidity()`: returns the humidity (in %) measured at this monitoring station at the time of measurement.
 - `getTemperature()`: returns the temperature (in degrees Celsius) measured at this monitoring station at the time of
   measurement.
@@ -127,20 +127,20 @@ Please see [CHANGELOG](CHANGELOG.md) for more information what has changed.
 This package comes with a [PHPUnit](https://phpunit.de) test suite. To run the tests, run the following command from the
 project directory:
 
-``` bash
-$ composer test
+```shell
+composer test
 ```
 
-or alternatively run with:
+,or alternatively run with:
 
-``` bash
-$ vendor/bin/phpunit
+```shell
+vendor/bin/phpunit
 ```
 
 ## Contributing
 
 Contributions are encouraged and welcome; I am always happy to get feedback or pull requests on GitHub :)
-Create [Github Issues](https://github.com/azuyalabs/waqi/issues) for bugs and new features and comment on the ones you
+Create [GitHub Issues](https://github.com/azuyalabs/waqi/issues) for bugs and new features and comment on the ones you
 are interested in.
 
 If you enjoy what I am making, an extra cup of coffee is very much appreciated :). Your support helps me to put more
diff --git a/SECURITY.md b/SECURITY.md
index ee351c2..cf33ea5 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -11,7 +11,7 @@ Please refer to the below table for the supported versions of this project.
 | < 1.0   | :x:                |
 
 As for supported PHP versions, this project only supports the actively supported versions of PHP. Currently, that is PHP
-8.0, 8.1 and 8.2. Please refer to the [supported versions](https://www.php.net/supported-versions.php) page, to find
+8.2 and 8.3. Please refer to the [supported versions](https://www.php.net/supported-versions.php) page, to find
 more details. When a version of PHP becomes EOL, generally a new release of this project will be issued that sunsets the
 support of that retired PHP version.
 
diff --git a/composer.json b/composer.json
index 7a59ce2..cadd017 100644
--- a/composer.json
+++ b/composer.json
@@ -1,6 +1,8 @@
 {
   "name": "azuyalabs/waqi",
   "description": "Simple PHP Wrapper for the World Air Quality Index API",
+  "license": "MIT",
+  "type": "library",
   "keywords": [
     "air quality",
     "AQI",
@@ -10,9 +12,7 @@
     "WAQI",
     "air"
   ],
-  "type": "library",
-  "homepage": "https://github.com/azuyalabs/waqi",
-  "license": "MIT",
+  "readme": "README.md",
   "authors": [
     {
       "name": "Sacha Telgenhof",
@@ -21,7 +21,7 @@
       "role": "Maintainer"
     }
   ],
-  "readme": "README.md",
+  "homepage": "https://github.com/azuyalabs/waqi",
   "support": {
     "issues": "https://gitlab.com/azuyalabs/waqi/-/issues",
     "source": "https://gitlab.com/azuyalabs/waqi",
@@ -33,22 +33,22 @@
       "url": "https://www.buymeacoffee.com/sachatelgenhof"
     }
   ],
-  "minimum-stability": "dev",
-  "prefer-stable": true,
   "require": {
-    "php": "^8.0",
-    "guzzlehttp/guzzle": "^7.4",
-    "ext-json": "*"
+    "php": "^8.2",
+    "ext-json": "*",
+    "guzzlehttp/guzzle": "^7.8"
   },
   "require-dev": {
-    "mockery/mockery": "^1.3",
-    "friendsofphp/php-cs-fixer": "^v3.14",
-    "phpunit/phpunit": "^9.5",
-    "phpstan/phpstan": "^1.4",
-    "fakerphp/faker": "^1.15",
-    "infection/infection": "^0.26.1",
-    "vimeo/psalm": "^5.7"
+    "fakerphp/faker": "^1.23",
+    "friendsofphp/php-cs-fixer": "^v3.15",
+    "infection/infection": "^0.26",
+    "mockery/mockery": "^1.6",
+    "phpstan/phpstan": "^1.10",
+    "phpunit/phpunit": "^9.6",
+    "vimeo/psalm": "^5.18"
   },
+  "minimum-stability": "dev",
+  "prefer-stable": true,
   "autoload": {
     "psr-4": {
       "Azuyalabs\\WAQI\\": "src"
@@ -59,23 +59,23 @@
       "Azuyalabs\\WAQI\\Test\\": "tests"
     }
   },
+  "config": {
+    "allow-plugins": {
+      "infection/extension-installer": true,
+      "composer/package-versions-deprecated": true
+    },
+    "sort-packages": true
+  },
   "scripts": {
-    "format": "vendor/bin/php-cs-fixer fix",
-    "phpstan": "vendor/bin/phpstan analyse",
-    "psalm": "vendor/bin/psalm --threads=2",
-    "test": "vendor/bin/phpunit",
-    "infection": "vendor/bin/infection run -j 2",
     "analyse": [
       "@phpstan",
       "@psalm",
       "@infection"
-    ]
-  },
-  "config": {
-    "sort-packages": true,
-    "allow-plugins": {
-      "infection/extension-installer": true,
-      "composer/package-versions-deprecated": true
-    }
+    ],
+    "format": "vendor/bin/php-cs-fixer fix",
+    "infection": "vendor/bin/infection run -j 2",
+    "phpstan": "vendor/bin/phpstan analyse",
+    "psalm": "vendor/bin/psalm --threads=2",
+    "test": "vendor/bin/phpunit"
   }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 1eda452..6dda623 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -2,33 +2,34 @@
 <!--
   ~ This file is part of the WAQI (World Air Quality Index) package.
   ~
-  ~ Copyright (c) 2017 - 2023 AzuyaLabs
+  ~ Copyright (c) 2017 - 2024 AzuyaLabs
   ~
   ~ For the full copyright and license information, please view the LICENSE
   ~ file that was distributed with this source code.
   ~
   ~ @author Sacha Telgenhof <me@sachatelgenhof.com>
   -->
-
-<phpunit bootstrap="vendor/autoload.php"
-         backupGlobals="false"
-         backupStaticAttributes="false"
-         colors="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         processIsolation="false"
-         stopOnError="false"
-         stopOnFailure="false"
-         verbose="true">
-    <testsuites>
-        <testsuite name="WAQI Test Suite">
-            <directory>tests</directory>
-        </testsuite>
-    </testsuites>
-    <filter>
-        <whitelist>
-            <directory suffix=".php">src/</directory>
-        </whitelist>
-    </filter>
+  <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    bootstrap="vendor/autoload.php"
+    backupGlobals="false"
+    backupStaticAttributes="false"
+    colors="true"
+    convertErrorsToExceptions="true"
+    convertNoticesToExceptions="true"
+    convertWarningsToExceptions="true"
+    processIsolation="false"
+    stopOnError="false"
+    stopOnFailure="false"
+    verbose="true"
+    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+  <coverage>
+    <include>
+      <directory suffix=".php">src/</directory>
+    </include>
+  </coverage>
+  <testsuites>
+    <testsuite name="WAQI Test Suite">
+      <directory>tests</directory>
+    </testsuite>
+  </testsuites>
 </phpunit>
diff --git a/psalm.xml.dist b/psalm.xml.dist
index c152451..e356627 100644
--- a/psalm.xml.dist
+++ b/psalm.xml.dist
@@ -2,7 +2,7 @@
 <!--
   ~ This file is part of the Yasumi package.
   ~
-  ~ Copyright (c) 2015 - 2023 AzuyaLabs
+  ~ Copyright (c) 2017 - 2023 AzuyaLabs
   ~
   ~ For the full copyright and license information, please view the LICENSE
   ~ file that was distributed with this source code.
diff --git a/rector.php b/rector.php
index a75a58a..2a3ac7d 100644
--- a/rector.php
+++ b/rector.php
@@ -4,12 +4,13 @@
 
 use Rector\CodeQuality\Rector\Class_\InlineConstructorDefaultToPropertyRector;
 use Rector\Config\RectorConfig;
+use Rector\Set\ValueObject\LevelSetList;
 use Rector\Set\ValueObject\SetList;
 
 return static function (RectorConfig $rectorConfig): void {
     $rectorConfig->paths([
-        __DIR__.'/src',
-        __DIR__.'/tests',
+        __DIR__ . '/src',
+        __DIR__ . '/tests',
     ]);
 
     // single rules
@@ -20,7 +21,7 @@
         SetList::CODE_QUALITY,
         SetList::DEAD_CODE,
         SetList::EARLY_RETURN,
-        SetList::PHP_80,
+        LevelSetList::UP_TO_PHP_82,
         SetList::TYPE_DECLARATION,
     ]);
 };
diff --git a/src/AirQuality.php b/src/AirQuality.php
new file mode 100644
index 0000000..c6ef2b5
--- /dev/null
+++ b/src/AirQuality.php
@@ -0,0 +1,203 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of the WAQI (World Air Quality Index) package.
+ *
+ * Copyright (c) 2017 - 2024 AzuyaLabs
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * @author Sacha Telgenhof <me@sachatelgenhof.com>
+ */
+
+namespace Azuyalabs\WAQI;
+
+use Azuyalabs\WAQI\Exceptions\InvalidAccessToken;
+use Azuyalabs\WAQI\Exceptions\QuotaExceeded;
+use Azuyalabs\WAQI\Exceptions\UnknownStation;
+
+interface AirQuality
+{
+    /**
+     * Retrieves the real-time Air Quality Index observation monitoring station name (or city name).
+     *
+     * If the $station argument is left out, the Air Quality Index observation is obtained of the nearest monitoring
+     * station close to the user location (based on the user's public IP address)
+     *
+     * @param ?string $station name of the monitoring station (or city name). This parameter can be left blank to get
+     *                         the observation of the nearest monitoring station close to the user location (based on
+     *                         the  user's public IP address)
+     *
+     * @throws QuotaExceeded
+     * @throws InvalidAccessToken
+     * @throws UnknownStation
+     */
+    public function getObservationByStation(string $station = null): void;
+
+    /**
+     * Retrieves the real-time Air Quality Index observation monitoring station name (or city name)
+     * by the given geographical coordinates.
+     *
+     * @throws QuotaExceeded
+     * @throws InvalidAccessToken
+     * @throws UnknownStation
+     */
+    public function getObservationByGeoLocation(float $latitude, float $longitude): void;
+
+    /**
+     * Returns information about the Air Quality Index measured at this monitoring station at the time of measurement.
+     *
+     * The array returned contains 4 elements:
+     *  - 'aqi': the AQI level (which is defined by the monitoring stations' dominant pollution type)
+     *  - 'pollution_level': a narrative describing the air pollution level
+     *  - 'health_implications': a narrative describing the health implications associated with the measured pollution
+     *                           level
+     *  - 'cautionary_statement': a cautionary statement associated with the measured pollution level (only for PM2.5)
+     *
+     * @return array{aqi: float, pollution_level: string, health_implications: string, cautionary_statement: string} structure containing the Air Quality Index measured at this monitoring station at
+     *                                                                                                               the time of measurement
+     */
+    public function getAQI(): array;
+
+    /**
+     * Returns the date/time the last measurement was taken.
+     *
+     * @return \DateTime the date/time the last measurement was taken
+     *
+     * @throws \Exception
+     */
+    public function getMeasurementTime(): \DateTime;
+
+    /**
+     * Returns information about this monitoring station.
+     *
+     * The array returned contains 4 elements:
+     *  - 'id': the unique ID for this monitoring station
+     *  - 'name': the name (or description) of this monitoring station
+     *  - 'coordinates': the geographical coordinates of this monitoring station ('longitude' and 'latitude')
+     *  - 'url': the URL of this monitoring station
+     *
+     * @return array{id: int, name: string, coordinates: array{latitude: float, longitude: float}, url: string} structure containing information about this monitoring station
+     */
+    public function getMonitoringStation(): array;
+
+    /**
+     * Returns a list of EPA attributions for this monitoring station.
+     *
+     * A list of one or more attributions is returned, of which each contains a name and a URL attribute.
+     *
+     * @return array<string, string> list of EPA attributions for this monitoring station
+     *
+     * @throws \JsonException
+     */
+    public function getAttributions(): array;
+
+    /**
+     * Returns the humidity (in %) measured at this monitoring station at the time of measurement.
+     *
+     * @return float|null the humidity (in %) measured at this monitoring station at the time of measurement.
+     *                    If the monitoring station does not measure humidity levels, a 'null' value is returned.
+     */
+    public function getHumidity(): ?float;
+
+    /**
+     * Returns the temperature (in degrees Celsius) measured at this monitoring station at the time of measurement.
+     *
+     * @return float|null the temperature (in degrees Celsius) measured at this monitoring station at the time of
+     *                    measurement. If the monitoring station does not measure temperature levels, a 'null' value is
+     *                    returned.
+     */
+    public function getTemperature(): ?float;
+
+    /**
+     * Returns the barometric pressure (in millibars) measured at this monitoring station at the time of measurement.
+     *
+     * @return float|null the barometric pressure (in millibars) measured at this monitoring station at the time of
+     *                    measurement. If the monitoring station does not barometric pressure levels, a 'null' value
+     *                    is returned.
+     */
+    public function getPressure(): ?float;
+
+    /**
+     * Returns the carbon monoxide (CO) level measured at this monitoring station at the time of measurement.
+     *
+     * CO concentration levels are typically expressed in Parts per million (PPM) or density, however the World Air
+     * Quality levels is using the US EPA 0-500 AQI scale.
+     *
+     * @return float|null the carbon monoxide (CO) level measured at this monitoring station at the time of measurement.
+     *                    If the monitoring station does not measure PM10 levels, a 'null' value is returned.
+     */
+    public function getCO(): ?float;
+
+    /**
+     * Returns the nitrogen dioxide (NO2) level measured at this monitoring station at the time of measurement.
+     *
+     * NO2 concentration levels are typically expressed in Parts per million (PPM) or density, however the World Air
+     * Quality levels is using the US EPA 0-500 AQI scale.
+     *
+     * @return float|null the nitrogen dioxide (NO2) level measured at this monitoring station at the time of
+     *                    measurement. If the monitoring station does not measure PM10 levels, a 'null' value is
+     *                    returned.
+     */
+    public function getNO2(): ?float;
+
+    /**
+     * Returns the ozone (O3) level measured at this monitoring station at the time of measurement.
+     *
+     * O3 concentration levels are typically expressed in Parts per million (PPM) or density, however the World Air
+     * Quality levels is using the US EPA 0-500 AQI scale.
+     *
+     * @return float|null the ozone (O3) level measured at this monitoring station at the time of measurement. If the
+     *                    monitoring station does not measure PM10 levels, a 'null' value is returned
+     */
+    public function getO3(): ?float;
+
+    /**
+     * Returns the level of respirable particulate matter, 10 micrometers or fewer (PM10), measured at this monitoring
+     * station at the time of measurement.
+     *
+     * PM10 levels are typically expressed in Parts per million (PPM) or density, however the World Air
+     * Quality levels is using the US EPA 0-500 AQI scale.
+     *
+     * @return float|null the level of particulate matter 10 micrometers or fewer (PM10), measured at this monitoring
+     *                    station at the time of measurement. If the monitoring station does not measure PM10 levels,
+     *                    a 'null' value is returned
+     */
+    public function getPM10(): ?float;
+
+    /**
+     * Returns the level of fine particulate matter, 2.5 micrometers or fewer (PM2.5), measured at this monitoring
+     * station at the time of measurement.
+     *
+     * PM2.5 levels are typically expressed in Parts per million (PPM) or density, however the World Air
+     * Quality levels is using the US EPA 0-500 AQI scale.
+     *
+     * @return float|null the level of particulate matter 2.5 micrometers or fewer (PM2.5), measured at this monitoring
+     *                    station at the time of measurement. If the monitoring station does not measure PM10 levels,
+     *                    a 'null' value is returned
+     */
+    public function getPM25(): ?float;
+
+    /**
+     * Returns the sulfur dioxide (SO2) level measured at this monitoring station at the time of measurement.
+     *
+     * SO2 concentration levels are typically expressed in Parts per million (PPM) or density, however the World Air
+     * Quality levels is using the US EPA 0-500 AQI scale.
+     *
+     * @return float|null the sulfur dioxide (SO2) level measured at this monitoring station at the time of measurement.
+     *                    If the monitoring station does not measure PM10 levels, a 'null' value is returned
+     */
+    public function getSO2(): ?float;
+
+    /**
+     * Returns the name of the primary pollutant at this monitoring station at the time of measurement.
+     *
+     * For example if the primary pollutant is PM2.5, the value of 'pm25' will be returned.
+     *
+     * @return string name of the primary pollutant at this monitoring station at the time of measurement
+     */
+    public function getPrimaryPollutant(): string;
+}
diff --git a/src/Exceptions/InvalidAccessToken.php b/src/Exceptions/InvalidAccessToken.php
index b69f22b..9a2746e 100644
--- a/src/Exceptions/InvalidAccessToken.php
+++ b/src/Exceptions/InvalidAccessToken.php
@@ -5,7 +5,7 @@
 /**
  * This file is part of the WAQI (World Air Quality Index) package.
  *
- * Copyright (c) 2017 - 2023 AzuyaLabs
+ * Copyright (c) 2017 - 2024 AzuyaLabs
  *
  * For the full copyright and license information, please view the LICENSE
  * file that was distributed with this source code.
@@ -15,12 +15,10 @@
 
 namespace Azuyalabs\WAQI\Exceptions;
 
-use Exception;
-
 /**
  * Class for representing the exception that an invalid access token has been given.
  */
-class InvalidAccessToken extends \Exception
+final class InvalidAccessToken extends \Exception
 {
     public function __construct()
     {
diff --git a/src/Exceptions/QuotaExceeded.php b/src/Exceptions/QuotaExceeded.php
index c373526..d277235 100644
--- a/src/Exceptions/QuotaExceeded.php
+++ b/src/Exceptions/QuotaExceeded.php
@@ -5,7 +5,7 @@
 /**
  * This file is part of the WAQI (World Air Quality Index) package.
  *
- * Copyright (c) 2017 - 2023 AzuyaLabs
+ * Copyright (c) 2017 - 2024 AzuyaLabs
  *
  * For the full copyright and license information, please view the LICENSE
  * file that was distributed with this source code.
@@ -15,8 +15,6 @@
 
 namespace Azuyalabs\WAQI\Exceptions;
 
-use Exception;
-
 /**
  * Class for representing the exception that the use of the WAQI API usage quota has been exceeded.
  *
@@ -24,7 +22,7 @@
  *
  * @see http://aqicn.org/api
  */
-class QuotaExceeded extends \Exception
+final class QuotaExceeded extends \Exception
 {
     public function __construct()
     {
diff --git a/src/Exceptions/UnknownStation.php b/src/Exceptions/UnknownStation.php
index 7ea0145..2ba82d0 100644
--- a/src/Exceptions/UnknownStation.php
+++ b/src/Exceptions/UnknownStation.php
@@ -5,7 +5,7 @@
 /**
  * This file is part of the WAQI (World Air Quality Index) package.
  *
- * Copyright (c) 2017 - 2023 AzuyaLabs
+ * Copyright (c) 2017 - 2024 AzuyaLabs
  *
  * For the full copyright and license information, please view the LICENSE
  * file that was distributed with this source code.
@@ -15,12 +15,10 @@
 
 namespace Azuyalabs\WAQI\Exceptions;
 
-use Exception;
-
 /**
  * Class for representing the exception that the WAQI API does not know the given monitoring station or city name.
  */
-class UnknownStation extends \Exception
+final class UnknownStation extends \Exception
 {
     public function __construct()
     {
diff --git a/src/WAQI.php b/src/WAQI.php
index a6ad273..f1ab084 100644
--- a/src/WAQI.php
+++ b/src/WAQI.php
@@ -5,7 +5,7 @@
 /**
  * This file is part of the WAQI (World Air Quality Index) package.
  *
- * Copyright (c) 2017 - 2023 AzuyaLabs
+ * Copyright (c) 2017 - 2024 AzuyaLabs
  *
  * For the full copyright and license information, please view the LICENSE
  * file that was distributed with this source code.
@@ -25,7 +25,7 @@
 use GuzzleHttp\Psr7\Message;
 use GuzzleHttp\Psr7\Utils;
 
-class WAQI
+final class WAQI implements AirQuality
 {
     /** The endpoint URL of the World Quality Index API. */
     private const API_ENDPOINT = 'https://api.waqi.info/api';
@@ -42,8 +42,7 @@ class WAQI
     public function __construct(
         /** World Air Quality access token. */
         private string $token
-    ) {
-    }
+    ) {}
 
     /**
      * Retrieves the real-time Air Quality Index observation monitoring station name (or city name).
@@ -59,10 +58,10 @@ public function __construct(
      * @throws InvalidAccessToken
      * @throws UnknownStation
      */
-    public function getObservationByStation(?string $station = null): void
+    public function getObservationByStation(string $station = null): void
     {
         try {
-            $this->request('feed/'.($station ?? 'here').'/');
+            $this->request('feed/' . ($station ?? 'here') . '/');
         } catch (GuzzleException|\JsonException $e) {
             throw new \RuntimeException($e->getMessage(), $e->getCode(), $e);
         }
@@ -79,7 +78,7 @@ public function getObservationByStation(?string $station = null): void
     public function getObservationByGeoLocation(float $latitude, float $longitude): void
     {
         try {
-            $this->request('feed/geo:'.$latitude.';'.$longitude.'/');
+            $this->request('feed/geo:' . $latitude . ';' . $longitude . '/');
         } catch (GuzzleException|\JsonException $e) {
             throw new \RuntimeException($e->getMessage(), $e->getCode(), $e);
         }
@@ -96,7 +95,7 @@ public function getObservationByGeoLocation(float $latitude, float $longitude):
      *  - 'cautionary_statement': a cautionary statement associated with the measured pollution level (only for PM2.5)
      *
      * @return array{aqi: float, pollution_level: string, health_implications: string, cautionary_statement: string} structure containing the Air Quality Index measured at this monitoring station at
-                            the time of measurement
+     *                                                                                                               the time of measurement
      */
     public function getAQI(): array
     {
@@ -197,15 +196,15 @@ public function getMonitoringStation(): array
      *
      * A list of one or more attributions is returned, of which each contains a name and a URL attribute.
      *
-     * @return array<string, mixed> list of EPA attributions for this monitoring station
+     * @return array<string, string> list of EPA attributions for this monitoring station
      *
      * @throws \JsonException
      */
     public function getAttributions(): array
     {
-        $data = \json_encode($this->raw_data->attributions, JSON_THROW_ON_ERROR);
+        $data = \json_encode($this->raw_data->attributions, \JSON_THROW_ON_ERROR);
 
-        if (!$data) {
+        if (! $data) {
             throw new \RuntimeException('unable to process attributions data');
         }
 
@@ -213,7 +212,7 @@ public function getAttributions(): array
             $data,
             true,
             512,
-            JSON_THROW_ON_ERROR
+            \JSON_THROW_ON_ERROR
         );
     }
 
@@ -365,7 +364,7 @@ private function request(string $uri): void
         $client = new Client(['base_uri' => self::API_ENDPOINT]);
 
         try {
-            $response = $client->request('GET', $uri, ['query' => 'token='.$this->token]);
+            $response = $client->request('GET', $uri, ['query' => 'token=' . $this->token]);
         } catch (ClientException|RequestException $e) {
             echo Message::toString($e->getRequest());
 
@@ -379,7 +378,7 @@ private function request(string $uri): void
             Utils::copyToString($response->getBody()),
             false,
             512,
-            JSON_THROW_ON_ERROR
+            \JSON_THROW_ON_ERROR
         );
 
         if ('ok' === $response_body->status) {
diff --git a/tests/WAQITest.php b/tests/WAQITest.php
index ef62147..9febb83 100644
--- a/tests/WAQITest.php
+++ b/tests/WAQITest.php
@@ -5,7 +5,7 @@
 /**
  * This file is part of the WAQI (World Air Quality Index) package.
  *
- * Copyright (c) 2017 - 2023 AzuyaLabs
+ * Copyright (c) 2017 - 2024 AzuyaLabs
  *
  * For the full copyright and license information, please view the LICENSE
  * file that was distributed with this source code.
@@ -35,7 +35,7 @@ protected function setUp(): void
         parent::setUp();
 
         $this->faker = Factory::create();
-        $this->waqi = \Mockery::mock(WAQI::class, [$this->faker->md5()]);
+        $this->waqi = \Mockery::mock(AirQuality::class);
     }
 
     protected function tearDown(): void
@@ -467,7 +467,7 @@ public function shouldRaiseExceptionWhenInvalidTokenByGeoLocation(): void
     private function assertValue(mixed $result, mixed $expectedValue, string $type): void
     {
         $this->assertEquals($expectedValue, $result);
-        $this->{'assertIs'.\ucfirst($type)}($result);
+        $this->{'assertIs' . \ucfirst($type)}($result);
         $this->assertNotEmpty($result);
         $this->assertNotNull($result);
     }