Feel the Air in Beijing and Shanghai

I recently had a trip to two major cities in China from November 28 to December 22, 2016 in Beijing and Shanghai. Unfortunately, Beijing is famous for the air pollution.  A picture at Greenpeace China‘s webpage shows how the city looks like:bj-greenpeace

Photo: Greenpeace

I can’t say it was because of the air in China. But I had allergic reaction two days after I arrived in China. I caught flu at the end of my trip, even I got the flu shot in the U.S. All my personal reaction might just be a coincidence. Is the air really horrible in major cities in China? Is the air better in the U.S? I found the data from Nov. 28 to Dec. 24, 2016 for Beijing and Shanghai.

For people in the U.S. never worried about air quality maybe unfamiliar with the AQI value. EPA scales the air from 0 to 500. The higher the value, the greater the level of air pollution and the greater the health concern. To visualize the effect, the AQI value is divided into six levels/colors. An AQI value below 100 is generally thought of as satisfactory.


Photo: EPA

In a website called AQI Study, a non-profit organization, the 6-color chart clearly indicated the historical Air Quality Index (AQI) in two cities.


Photo: Beijing AQI, Nov. 28 to Dec. 24, 2016, from http://www.aqistudy.cn


Photo: Shanghai AQI, Nov. 28 to Dec. 24, 2016, from http://www.aqistudy.cn

It is clear, 2/3 of the time (by hour) in Beijing is “smoggy”. Sometimes, the AQI value can reach a spike around a terrifying 450. While in Shanghai, 2/3 of the time (by hour) is acceptable, with an AQI value below 100.

Meanwhile in December, how about the air in the U.S.? I found a website called AirNow, where you can find both the real-time and historical AQI data in the U.S. and Canada.

In December, the air in New York City seemed fine, while it was another story in California-Nevada region.

First, let’s see NYC data. Most of the days, the air is “good”, The city had two “moderate days” on Dec. 21st and 22nd. Overall, the air in the Big Apple is accepted by EPA standard.

nyc aqi.png

Photo: NYC AQI, from airnow.gov

California had some unhealthy, very unhealthy and even hazardous days in December. The most polluted areas are near Sacramento/Carson City and San Diego.

CA and NV aqi.png

Photo: California-Nevada AQI, from airnow.gov

For example, December 6, 2016 was not a healthy day. The daily combined data shows a “hazardous spot” near Carson City.

CA and NV one day.png

Photo: Combined daily AQI in California-Nevada, from airnow.gov

In general, people in the U.S. have much better air to breath safely, except a small portion of the country. On the other hand, most of the people in China are still breathing the polluted air.

Winter usually is the worst in China when the northern part of the country starts providing space heating using coal. A real-time national monitoring data shows how the air in most cities are unhealthy on January 2, 2017, 9pm.

real time.png

Photo: Real Time China’s AQI, from http://www.aqistudy.cn

If you’d like to explore more areas in the U.S., feel free to use this map.

I have heard some of my Chinese friends are installing whole-house air purifiers. It is not the regular stand-alone machine, rather something integrated to the air exchanger. When installing a HRV or ERV* to a building or an apartment unit, American think very limited about the air purifier unless they are worried about allergy. However, slowly it becomes popular in China. My friends in China who want to clean all the incoming air told me they would buy the HRV/ERV machines from Korea or Japan where people have the similar concern about the air.

* HRV/ERV: Heat Recovery Ventilator or Enthalpy Recovery Ventilator controls the ventilation in a building where the incoming air is purified and pre-heated/pre-cooling by the exhaust air through a heat/enthalpy exchanger. If the machine can recover the moisture, we call it Enthalpy Recovery Ventilator, otherwise Heat Recovery Ventilator.


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