AQI

Air Quality Index

I’v been experimenting to fetch data related to AQI in China recently.

A good resource is http://aqicn.org, which provides air pollution data in a good way by city, and I try to write a python script to crawl the data from it.

	#-*-coding: utf-8 -*-
	#!/usr/bin/python
	from datetime import datetime
	import pytz
	import requests
	from bs4 import BeautifulSoup
	class NetworkException(Exception):
	pass
	def get_aqi(city):
	base_url = 'http://aqicn.org/city/'
	city_url = base_url + city
	headers = {
	'User-Agent': 'Mozilla/5.0'
	}
	r = requests.get(city_url, headers=headers)
	if r.status_code == 200:
	html_doc = r.content
	soup = BeautifulSoup(html_doc, 'html.parser')
	aqi = soup.find(id='aqiwgtvalue').string
	pm25 = soup.find(id='cur_pm25').string
	pm10 = soup.find(id='cur_pm10').string
	o3 = soup.find(id='cur_o3').string
	no2 = soup.find(id='cur_no2').string
	so2 = soup.find(id='cur_so2').string
	co = soup.find(id='cur_co').string
	temp = soup.find(id='cur_t').string
	dew = soup.find(id='cur_d').string
	pressure = soup.find(id='cur_p').string
	humidity = soup.find(id='cur_h').string
	wind = soup.find(id='cur_w').string
	tz = pytz.timezone(pytz.country_timezones('cn')[0])
	d = datetime.now(tz)
	timestamp = d.strftime("%Y-%m-%d %H:%M:%S")
	return dict(aqi=aqi, pm25=pm25, pm10=pm10, o3=o3, no2=no2, so2=so2, co=co, temp=temp, dew=dew, pressure=pressure, humidity=humidity, wind=wind, timestamp=timestamp)
	else:
	raise NetworkException

view raw aqicn.py hosted with ❤ by GitHub

Another website is http://www.stateair.net/, it reports AQI from US consulate in Chinese major cities, i.e. Beijing, Shanghai, Guangzhou, Chengdu and Shenyang. Similarly, the code to fetch data from it shown below.

	import requests
	from bs4 import BeautifulSoup
	class NetworkException(Exception):
	pass
	cities = {'beijing': '1', 'chengdu': '2', 'guangzhou': '3', 'shanghai': '4', 'shenyang': '5'}
	def get_pm25_24h(city):
	city_code = cities.get(city.lower())
	if not city_code:
	return city + " not available."
	base_url = 'http://www.stateair.net/web/rss/1/'
	r = requests.get(base_url + city_code + '.xml')
	if r.status_code == 200:
	data = []
	xml_doc = r.content
	soup = BeautifulSoup(xml_doc, 'xml')
	items = soup.find_all('item')
	for item in items:
	title = item.title.string
	link = item.link.string
	description = item.description.string
	param = item.Param.string
	conc = item.Conc.string
	aqi = item.AQI.string
	desc = item.Desc.string
	reading_date_time = item.ReadingDateTime.string
	d = {
	'title': title,
	'link': link,
	'description': description,
	'Param': param,
	'Conc': conc,
	'AQI': aqi,
	'Desc': desc,
	'ReadingDateTime': reading_date_time
	}
	data.append(d)
	return data
	else:
	raise NetworkException

view raw pm25.py hosted with ❤ by GitHub

Both of the code above are using Python and handy packages like requests and Beautiful Soup.

The stateair website also provides historical data for download in CSV format, therefore I use those data to create a simple visulization page. Check it from https://chuanjin.github.io/pm25/ and source code is availabe from Github repo.

Last but not least, I found pm25.in website, and they provide real time data for all Chinese cities, even better, they have opened their API for develper and I also created a Python library based on their API. Code available from https://github.com/chuanjin/python-aqi-zh