OpenAQ API

api.openaq.org · Science

Science No Auth Free & Open Environment Air Quality Climate

Real-time and historical air quality data from 30,000+ monitoring stations in 100+ countries. PM2.5, PM10, ozone, NO2, CO, SO2 measurements. Free, no API key.

Authentication

No authentication requiredFree to use with no key needed.

Sample Requests

GET Get locations

Get recently updated air quality stations in the US.

https://api.openaq.org/v3/locations?sort=desc&limit=5&order_by=lastUpdated&country_id=13

Hover any highlighted part to learn what it does

curl -X GET "https://api.openaq.org/v3/locations?sort=desc&limit=5&order_by=lastUpdated&country_id=13"

import requests
params = {
    "sort": "desc",
    "limit": "5",
    "order_by": "lastUpdated",
    "country_id": "13"
}
response = requests.get(
    "https://api.openaq.org/v3/locations",
    params=params,
)
print(response.json())

const url = new URL('https://api.openaq.org/v3/locations');
url.searchParams.set('sort', 'desc');
url.searchParams.set('limit', '5');
url.searchParams.set('order_by', 'lastUpdated');
url.searchParams.set('country_id', '13');

const response = await fetch(url); 
const data = await response.json();
console.log(data);

package main

import (
	"fmt"
	"io"
	"net/http"
	"net/url"
)

func main() {
	baseURL, _ := url.Parse("https://api.openaq.org/v3/locations")
	q := baseURL.Query()
	q.Set("sort", "desc")
	q.Set("limit", "5")
	q.Set("order_by", "lastUpdated")
	q.Set("country_id", "13")
	baseURL.RawQuery = q.Encode()
	targetURL := baseURL.String()
	req, _ := http.NewRequest("GET", targetURL, nil)

	client := &http.Client{}
	resp, _ := client.Do(req)
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	fmt.Println(string(body))
}

require "net/http"
require "json"

uri = URI("https://api.openaq.org/v3/locations")
uri.query = URI.encode_www_form({
  "sort" => "desc",
  "limit" => "5",
  "order_by" => "lastUpdated",
  "country_id" => "13"
})

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"

req = Net::HTTP::Get.new(uri)

res = http.request(req)
puts JSON.parse(res.body)

<?php
$url = "https://api.openaq.org/v3/locations?" . http_build_query([
    "sort" => "desc",
    "limit" => "5",
    "order_by" => "lastUpdated",
    "country_id" => "13"
]);
$opts = ["http" => [
    "method" => "GET",
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

GET Get measurements

Get PM2.5 measurements for a station.

https://api.openaq.org/v3/measurements?limit=10&location_id=1&parameter_id=2

Hover any highlighted part to learn what it does

curl -X GET "https://api.openaq.org/v3/measurements?limit=10&location_id=1&parameter_id=2"

import requests
params = {
    "limit": "10",
    "location_id": "1",
    "parameter_id": "2"
}
response = requests.get(
    "https://api.openaq.org/v3/measurements",
    params=params,
)
print(response.json())

const url = new URL('https://api.openaq.org/v3/measurements');
url.searchParams.set('limit', '10');
url.searchParams.set('location_id', '1');
url.searchParams.set('parameter_id', '2');

const response = await fetch(url); 
const data = await response.json();
console.log(data);

package main

import (
	"fmt"
	"io"
	"net/http"
	"net/url"
)

func main() {
	baseURL, _ := url.Parse("https://api.openaq.org/v3/measurements")
	q := baseURL.Query()
	q.Set("limit", "10")
	q.Set("location_id", "1")
	q.Set("parameter_id", "2")
	baseURL.RawQuery = q.Encode()
	targetURL := baseURL.String()
	req, _ := http.NewRequest("GET", targetURL, nil)

	client := &http.Client{}
	resp, _ := client.Do(req)
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	fmt.Println(string(body))
}

require "net/http"
require "json"

uri = URI("https://api.openaq.org/v3/measurements")
uri.query = URI.encode_www_form({
  "limit" => "10",
  "location_id" => "1",
  "parameter_id" => "2"
})

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"

req = Net::HTTP::Get.new(uri)

res = http.request(req)
puts JSON.parse(res.body)

<?php
$url = "https://api.openaq.org/v3/measurements?" . http_build_query([
    "limit" => "10",
    "location_id" => "1",
    "parameter_id" => "2"
]);
$opts = ["http" => [
    "method" => "GET",
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

Postman Setup Guide

Get Postman ↗

No API key needed
Countries: GET /v3/countries
Locations in country: GET /v3/locations?country_id=13&limit=10 (13=US)
Parameter IDs: 1=PM1, 2=PM2.5, 3=PM10, 4=NO2, 5=CO, 6=SO2, 7=O3
Measurements: GET /v3/measurements?location_id=ID&parameter_id=2&limit=10

What can you build with OpenAQ API?

OpenAQ API is a Science API. Developers commonly use science APIs for:

accessing research datasets and scientific literature
powering academic and R&D applications
running scientific calculations and simulations
visualising experimental and observational data
integrating with research and reference databases

No authentication required. This API is open — no signup or key needed. Ideal for quick prototypes and public-facing features. OpenAQ API is free to use, making it a low-risk choice to experiment with.

New to APIs? Read our beginner's guide

Open documentation ↗