Indoor Air Quality

Why does air quality really matter to me in China anyways?

  • The US EPA estimates that people spend more than 90% of their time indoors.  However, indoor air is typically 5-10 times worse than the outdoor air and concentration of individual air pollutants indoors can easily be 100 times higher than outside[1]
  • Asthma rates have doubled since 1980, with indoor air estimated to have a 50% impact
  • Children are more susceptible because their immune systems are not yet fully developed and they breathe in 50 percent more air per pound of body weight than adults
  • Air pollution causes premature births, low-birth weight babies, and depresses lung function.  It has also been blamed for China’s rising rates of cancer. Lung cancer is now the leading cause of death in China, and has risen 18.5 percent to 34 per 100,000 people in just the last five years
  • It is estimated that 26 percent of all deaths in China are caused by respiratory illnesses (compared with 2 or 3 percent in the U.S.).[2] The World Bank and the WHO attribute about 300,000 premature deaths due to indoor air pollution a year in China.

What are the issues around indoor air in China?

One look at the haze outside most fall or winter mornings tells us that the air quality in Shanghai has much to be desired.  The average air quality in terms of particulate level, is often three to four times worse than the WHO standard of 150,000 particles per liter of air (2.5 microns or smaller).  For this reason, most of us try to limit significant exposure outdoors and prefer to stay indoors.  In fact, the according to the EPA, the vast majority of us spend close to 90% of our time indoors.

Ironically, indoor air is often as bad as or worse than outdoor air.  This is because today’s homes are built to be highly efficient, tightly sealed envelopes that continuously circulate the same air.  Without proper ventilation and filtration, pollutants build up in the air that we breathe.

At the same time, there are sources of indoor air pollution unique to China.  The prevalence of new buildings and furnishings, high use of particle board, and lower awareness of healthy construction makes formaldehyde and other VOCs a significant issue.  While the US has passed a domestic bill regulating the amount of formaldehyde emissions in composite wood products, there is no similar regulation for Chinese products.  In addition, homes here have the same pollution sources as they do elsewhere: household cleaning agents, mold, cooking, dust mites, pet dander, just to name a few.  Together, this leads to a level of indoor air quality that poses an unacceptable level of risk to our health as well as our comfort.

Our friends are frequently dismayed when they learn that both outdoor and indoor air quality in China is poor.  Many have been accustomed to improving air quality simply by opening windows and ventilating.  This is not an acceptable option in China, given the outdoor air quality.  What is one to do?  Fortunately, there are solutions available and some are surprisingly simple.

Contact Us about China indoor air

What’s in the air and where is it from?

The air we breathe is infused with particulates and chemical vapors, both organic and inorganic.  A glance under an electron microscope of a sampling of the air in a typical home reveals the presence of a host of particulate matter (PM) :  human skin particles, dust mite body parts and droppings, mold spores, pollen, pet dander, and dust.  Some can be seen with the naked eye, others are so small they are measured in tenths of a micron (one-millionth of a meter) and only visible with the aid of an electron microscope.  The human eye can detect particles about 40 microns in diameter, which is about the width of a human hair.  For the particle size of many airborne particles, see this link.

Particulates larger than 100 microns settle out of the air quickly and are not at risk for inhalation.  Particles that are larger than 10 microns are considered of potential damage to health, but the EPA considers particles of 2.5 microns or less to be of greatest health danger to the general population because they can penetrate through the nose hairs, throat mucous, lungs, and directly into our gas exchange regions and into the bloodstream.  Particulates of this size (called PM 2.5) can cause respiratory disease and infection – asthma, shortness of breath, bronchitis, pneumonia, and lung cancer.  Particulates also increase blood pressure, contributing to heart attacks and strokes.  High levels of airborne lead are usually the result of the resuspension of lead from soil and dust outside the house that is tracked in.

Recent studies have correlated PM 2.5 exposure (75th percentile in level compared to 25th percentile) with birth weight deficit of 189g and 1.1cm smaller birth length in male infants.[1] One of the same studies further concluded that birth weight deficit was not attributable to environmental tobacco smoke, a common belief.


[1] “Gender differences in fetal growth of newborns exposed prenatally to airborne fine particulate matter.” Environmental Research. 3/3/09

Volatile Organic Compounds (VOCs):

In addition to particulates, volatile organic compounds (VOCs) are gases released from solid state during the aging and degradation of materials.  Think of the smell of new cars or a new carpet.  VOCs contribute to sinus and lung irritation and can even compromise the immune system.

Formaldehyde is one of the most common VOCs that you will encounter in China, often when walking through new buildings or market stalls.  Colorless and odorless at low concentrations, it nonetheless can cause burning of the eyes, tightness in the chest, headaches, and can trigger asthmatic attacks and depression.  It is readily found in cabinets, bookcases, textiles, carpets and anywhere that particle or pressboard is found as a binding agent to hold the wood chips or fibers together. Indoor concentrations are dependent on the age of the source, ventilation rate, indoor and outdoor temperatures, and humidity.

Does any of this really matter?

Environmental-related deaths in ChinaMore people die from ambient air pollution (indoors and outdoors) in China than in any other country in the world.  The more particles there are, the more difficult it is for our bodies to process the air and the more likely we may develop an allergic reaction.  Ironically, our body does a fairly good job of dealing with the larger particles, that is those above the size of 3 microns, which is visible to the naked eye.  What is more dangerous are particles below 3 microns which bypass our body’s filters and lodge deep in the lungs or enter in the bloodstream, carrying with them allergens, chemicals, or carcinogens.

Formaldehyde is a known irritant and sensitizer. Symptoms include dry or sore throat, nosebleeds, headaches, fatigue, memory problems, nausea, dizziness, breathlessness, and eye irritation.  Concentrations as low as 0.01 ppm have been reported to affect sensitive individuals.  In June, 2010, the US EPA released a report that upgraded formaldehyde from a suspected to a “known” carcinogen.  “There is sufficient evidence of a causal association between formaldehyde exposure and cancers of the upper respiratory tracts.”[3] As with most air pollutants, children are most at risk.  The EPA investigators demonstrated to a high level of statistical significance that “increased residential formaldehyde exposures were associated with decreased pulmonary function as measured by peak expiratory flow rate in children.”

So what do I need to do to improve my indoor air quality?

1. Assess. The first step is to identify what aspect of air quality may need special attention.  A starting point is to test your home’s air quality.  When testing your home, it is important to request an interpretation of the test results in a format that is meaningful.  We provide all of our clients with a customized test output that not only explains where their home stands against the Chinese national standard, but also against often more rigorous international standards.  In addition to the standards, you should identify areas of unique sensitivities.  Although you may fall within the standards for particulate matter, for instance, if your child is particularly susceptible to asthma or allergies, it may make sense to focus on remediating that aspect of air.Allergies in China

2. Identify the source.  Once we’ve identified which area to remediate, attempt to determine the causes.  For instance, if high levels of VOCs are found, carpets, cabinets, and newly painted items are frequently the sources.  Root cause analysis is included in our assessment services.

3. Remediate.  The general principle is that it is more effective to eliminate the source of the pollutant than to try to remove the aftereffects.  For instance, it is better to keep pets out of the bedroom at night or to remove a formaldehyde-emitting rug than to implement an air filter to passively filter dander and VOCs.  Similarly, instead of using additional chemical sprays to reduce formaldehyde in furnishings, consider limiting your purchases to low formaldehyde products such as solid wood and metal materials instead of pressed board.

A. Source elimination/separation. Cleaning and removal of source
B. Containment of vapors. Ventilation, oxidation sprays, and/or sealants.
C. Filters & air purifiers to condition the air
D. Green plants. Certain plants not only remove toxic VOCs but also exchange carbon dioxide with fresh oxygen that is necessary when windows are shut and purifiers are running continuously.  Here’s something on what plants can achieve: NASA study on house plants that improve air quality

For a real-world large-scale case study of how green plants reduced energy use by 15% and improved employee productivity by 20%, check out this presentation by researcher Kamal Meattle at the 2009 TED Conference.  Watch the video

China air pollution


[1] “A comparison of indoor and outdoor concentrations of hazardous air pollutants,” Inside IAQ (Spring/Summer 1998)
[2] www.epa.gov/iris June 2010
[3] “Air Pollution in China,” The Washington Post, 8/4/2008