What are VOCs?

Have you ever heard the term VOC ? VOCs cause the generation of photochemical smog and are a harmful and toxic to the human body. Governments of many countries have amended Air Pollution Control Acts and have worked to improve VOC emission control in recent years. In this section, we outline what VOCs are, how they are generated, and how they are regulated.

What are VOCs ? - Definition of VOCs & their Compounds

VOC is an abbreviation for Volatile Organic Compound. They are substantial contributor to the generation of smog due to the photochemical reactions they create in the atmosphere. “VOCs” is a general description of these airborne volatile organic compounds in the atmosphere.
There are approximately 200 kinds of applicable VOCs, such as Toluene, Xylenes, 1,3,5-Trimethylbenzene, Ethyl Acetate, Decane, Methyl Alcohol, Dichloromethane, etc. that are airborne in many facilities. There are various sources of generation such as paint solvent (thinner), adhesive materials, ink for printing, some cleaning agents, etc

Where do VOCs come from ?

Processes which produce and consume paint materials, fuel, chemicals, ink for printing and adhesive materials, account for 78 % of total exhaust gases.
According to the report by Ministry of Economy, Trade and Industry and Ministry of the Environment in Japan in 2014, paint booths have the biggest contributor to emissions at 40 %, followed by fuel (evaporated gases) at 19 %, chemical processes at 7% and ink for printing at 6%.
In other study, the National Institute for Environmental Studies in Japan announced in 2005 that VOC exhaust volume resulting from the operation of vehicles themselves made up approximately 15% of all VOC exhaust in Japan.
Then, after further analysis in detail, they found this number to be 27 % when including emissions during cold starts, idling for engine and fueling. Furthermore, it is widely suspected that automotive industries actually account for a larger percentage of VOC volume if parts manufacturing, assembling the car and maintenance services are taken into account.

VOC emission standard in the Clean Air Act must be followed.

Japanese Government amended the Air Pollution Control Act in May, 2004, and started enforcing the amended emission regulation from 2006. Through this legal action, the government aims to control VOC emission which causes SPM and oxidants by using a proper combination of “legal regulation” and “self-regulatory organizational efforts”

Particularly, the following process and facilities, that are known to release large amount of exhaust, are targeted for emission control.

• Paint booth and paint finishing process like drying and baking
• Drying facilities in chemical production processes
• Cleaning processes for industrial applications and their drying processes
• Drying and curing in the printing process
• Storage for VOCs
• Drying and hardening processes after applying adhesives

In accordance with the application and scale of exhaust facilities, there are emission standards between approx. 400 ppmC and 60,000 ppmC to be enforced. If a facilities targeted for emission control does not achieve the standard level, any party who has violated the provision of Article 33 can be punished by imprisonment with work for not more than one year or be fined up to one million yen. Also, any notifiable party who has violated the provision of Article 34 can be punished by imprisonment with work for not more than three months or be fined up to three hundred thousand yen.

What kind of measuring methods are available ?

VOC measuring method in the exhaust gases shall be shown below. (ref. Report by Central Environment Council)

Measuring low levels of VOC concentration

When the concentration of a test sample is within the measuring range of the analysis equipment, this test method shall be applied. Exhaust gas which is collected with a sampling bag in the field is introduced into the analysis equipment directly and then measured.

Measuring high levels of VOC concentration

When the concentration of a test sample is beyond the measuring range of the analysis equipment, this test method shall be applied. Exhaust gas is collected with a sampling bag in the field. Part of the exhaust gas is diluted in a new separate sampling bag and the diluted exhaust gas is introduced into the analysis equipment and then measured.

One of two types of analysis equipment is used for measuring VOC concentration in exhaust gases.

Catalytic Oxidization - Non-Dispersion Infrared Ray analyzer

A VOC exhaust gas sample is introduced into a heated catalyst charged vessel and decomposed into carbon dioxide by oxidization. The concentration of the decomposed carbon dioxide is measured by infrared absorption intensity.