Shanghai — Auto interior odors and volatile organic compound (VOC) emissions are coming under more scrutiny in China, even as they take a back seat in the United States.
Speakers and attendees dived deep into this subject at the Society of Plastics Engineers' Automotive TPO Engineered Polyolefins Global Conference, held March 21-24 in Shanghai.
Testing results are complicated by the sheer number of different ways of testing for VOCs and odors as well as the many standards.
“Everyone has their own way of skinning a cat,” said Alec Lang, president of Reliable Analysis Inc., a Madison Heights, Mich.-based accredited testing lab with offices in Shanghai. Many automakers have their own standards that vary slightly from the others.
Laura Shereda of Asahi Kasei Plastics North America Inc. said the varied standards make it hard to compare. “Sometimes this happens with testing and creating standards, especially when things are subjective and difficult to measure,” she said.
According to the speakers, while standards are OEM-specific in the U.S. and Germany, China has a national standard for VOC emissions that is more stringent than many other countries around the world. Currently the national standard (GBT 27630-2011 Guideline) is not mandatory, but it is due to become compulsory soon. The standards are undergoing a preliminary feedback stage and a final version will soon be released. A relatively new international ISO testing standard has become available, but OEMs that have previously developed their own standards may not choose to switch.
“In the U.S., we have not been pushing VOC testing at all,” said an industry insider who asked not to be named. “The only reason why GM, Ford and Chrysler have been pushing the VOC specs is so they can sell cars in China.”
One reason why VOC testing has not been as much of a priority in the U.S., said Reliable Analysis' Lang, is that there are more standards in place already for base materials. “We already have restricted substances. So for base materials, it's not allowed to use certain chemicals by default. For example, formaldehyde, we don't use that in our cars.”
As for testing, OEMs in different regions prefer to use different methods. German OEMs prefer to use the SHED chamber approach, which is widely seen as the most technically accurate, but it is also the most expensive and slowest method, because only one part can be measured per day. Chinese OEMs tend to use the bag approach, which can be scaled for whole cars, is less expensive to carry out, and can be implemented faster. Lang said, “These are all semi-quantitative test procedures. They are not comparable apples to apples.”
No one standard for odor
Odor tests have their own complicating factors.
“There is really no good odor test that is standardized. If anyone knows of one please let me know,” Shereda said. “Every one is different, so it is very hard. The odor tests are not a scientific process. Tests are conducted by people with trained noses.
“No two people are the same. Often it is a matter of preference. There are differences in odor preferences across regions globally. Often a feeling or emotion is attached to a certain smell.”
Several attendees highlighted that the contrast between emphasis on VOC emissions in China and the reduced emphasis in the U.S. is also complicated by cultural factors.
Alec Lang explained, “Back home [in the U.S.], growing up you liked new car smell. People have those [car scent] ‘trees' that hang from the car that has new car scent.”
But in China, he said, people have negative associations with the smell. “Odor testing is a super subjective test, because it is done by the human nose. What is pleasant for me is different for others,” he added.
“There are differences across regions globally,” Shereda said. Many regions request neutral smells. Some regions allow smells that are more perfume. But it is difficult to tell this until you've gone to the region, produced the material and talked to the supplier.”
Another confusing factor is that the connection between odor and VOCs is also not always clear. “Just because there is low odor does not mean that there are low VOCs,” said Shereda. “Some VOCs you can smell, some you cannot.”
Getting rid of an odor is difficult as well, she said.
“Sometimes there are many different molecules and sometimes it is the combination that makes the odor that is unpleasant. A lot of times suppliers and molders use products that are considered trade secrets so if we don't know the chemistries of these products, sometimes they may have interactions or produce unpleasant smells despite our attempts to remove them.”
The multitude of variables lead to different odors and emissions. What speakers and attendees at the conference were left to ponder was whether VOCs and odors will ever be fully controlled.
