Air Quality

{
  "dominant_pollutant": "pm2_5",
  "european_aqi": 37,
  "health_note": "air quality is satisfactory",
  "location": {
    "elevation_m": 27,
    "lat": 40.71,
    "lon": -74.01,
    "timezone": "America/New_York"
  },
  "next_24h": {
    "min_us_aqi": 33,
    "peak_at": "2026-10-13T17:00",
    "peak_category": "moderate",
    "peak_us_aqi": 77,
    "trend": "worsening"
  },
  "observed_at": "2026-10-12T18:00",
  "pollen_grains_m3": null,
  "pollen_note": "pollen is modelled for Europe only",
  "pollutants_ugm3": {
    "carbon_monoxide": 291,
    "nitrogen_dioxide": 22.6,
    "ozone": 56,
    "pm10": 6.8,
    "pm2_5": 6.8,
    "sulphur_dioxide": 0.9
  },
  "source": "Open-Meteo air quality (CAMS)",
  "us_aqi": 33,
  "us_aqi_by_pollutant": {
    "carbon_monoxide": 2,
    "nitrogen_dioxide": 11,
    "ozone": 33,
    "pm10": 6,
    "pm2_5": 33,
    "sulphur_dioxide": 0
  },
  "us_aqi_category": "good",
  "uv_index": 0
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://saylorinnovations.com/api/air/quality?lat=40.71&lon=-74.01'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://saylorinnovations.com/api/air/quality?lat=40.71&lon=-74.01' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.01 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.01" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.01 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fsaylorinnovations.com%2Fapi%2Fair%2Fquality
const res = await pay("https://saylorinnovations.com/api/air/quality?lat=40.71&lon=-74.01");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.01 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.01"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://saylorinnovations.com/api/air/quality?lat=40.71&lon=-74.01")
    print(res.status_code, res.text)