Check your VOCs at the door right now if you plan to do cleaning or other work in the Los Angeles basin, many countries of the EU, Japan, or perhaps even inside your own facility tomorrow.

This column is about what that means and why it’s so. This column is about why there has been major change in cleaning operations but less so in the baking of bread.

Smoggy Chemistry

Some chemicals, including solvents, interact with UV light and oxides of nitrogen from combustion emissions in the earth’s troposphere. The chemistry is complicated and not completely understood. But the result is simple and easily understood– breath-stopping smog.

Legislators and Regulators

International, national, regional, and local legislation has sought to limit the use and methods of use of chemicals which can either participate in those chemical reactions or become pollution in the troposphere. Regulations produced by that legislation, though well-intentioned, are often dictatorial and occasionally miss the whole point. Specifically, these regulations ban the use of or strictly limit the emission of chemicals defined as Volatile Organic Carbons (VOCs).

An Approach in the U.S.

In the U.S., the EPA has sought to limit atmospheric pollution by restricting use of chemicals which react with UV light. They have defined VOCs as all organic chemicals which react with UV light at above a certain rate. Acetone, HFE-7100, and perchloroethylene are VOC exempt because their measured response rates with photons are suitably low. Ethanol, n-propyl bromide, and nearly all other cleaning solvents are classified as VOCs in the U.S.

It’s a simple and binary system. In the U.S., reactivity of a solvent with UV light is either below that of ethane (the “bright line” standard as negligible) and the solvent isn’t classified and regulated as a VOC, or the solvent is regulated as a VOC.

Another Approach in the EU

Legislators in the EU and elsewhere take a different point of view. They ignore tropospheric reactivity of chemicals. Regulations seek to block chemicals from ever reaching the troposphere.

Regulation in the EU is also simple and binary. It is only the “V” in VOC which matters. Solvents exempt from VOC classification in most of the EU are those which are relatively non-volatile. The “bright-line” standard is usually that the vapor pressure at 20 EC is less than 0.075 mm Hg, or the chemical is a VOC. I find it interesting that this standard is not one based on evaporation rate but one based on vapor pressure – when evaporation is the outcome to be avoided.

The Effect on Cleaning Work

Solvents are chosen for cleaning based on the nature of the job. Yet environmental regulations can dominate the selection. Nowhere is this more true than in the Los Angeles basin or the EU. This leads to an emphasis on non-solvent cleaning (aqueous or no-clean), or enclosed machines which can have negligible emission rates. Either approach to VOC definition should make you think twice about buying an open-top vapor degreaser.

Our Daily Bread

One would be wrong to expect this sea change in cleaning methodology to have paralleled similar change in other production operations. For the purpose of illustration only, consider the baking industry. Baking involves fermentation of yeast, which produces ethanol that is emitted from baking ovens. The UK’s inventory of non-methane VOCs shows that in 1998, around 64 MM tonnes of ethanol were emitted in production processes. The same values for perchloroethylene were 0.94, methylene chloride 3.28, and 1,1,1- trichloroethane 0.42. Values are similar from 1996 to 2000.

This author believes the reason for the difference of emphasis on containing ethanol emissions vs. those of cleaning solvents is that ethanol does not manifest the UK toxicity profile of highly-dangerous Strategy Pollutants, and some cleaning solvents do so.

Summary

There is legitimate worldwide debate about the approach to preventing smog. Regulations aimed at reducing formation of smog properly limit use of cleaning solvents, and other chemicals. But the effect is not the same in all industries. From the standpoint of smog production only, switching everyone to the Atkins diet and forgoing bread would have more positive impact on smog than would sealing or prohibiting all vapor degreasers.

Reference:

"National Atmospheric Emissions Inventory," http://www.aeat.co.uk/netcen/airqual/naei/annreport/annrep98/chap5_5.html