Isocyanates and Asthma

Isocyanates are in the hardener of many autobody paints

You may come in contact with them when mixing hardener, spraying hardener, and cleaning equipment after spraying an isocyanate-containing hardener. They react readily with other chemicals to form polyurethane, which makes the finish on cars hard, durable and resistant to weather and UV light. However, they can also react with parts of the body and be harmful to your health.

Autobody paints usually contain hexamethylene diisocyanate (HDI) and/or isophorone diisocyanate (IPDI). Look for the word “isocyanate” or these chemical names on a product label or MSDS to determine if a product you are using contains isocyanates.

Isocyanates can cause asthma

Isocyanates can cause you to develop asthma even if you have never had it before. At first you may only have asthma attacks when you are exposed to isocyanates. If you leave the environment where you are exposed to isocyanate, or if the exposures are controlled well enough, you may never have any more symptoms of asthma and will be fine. But if you continue to be exposed, you may go on to develop regular asthma and have asthma attacks that are triggered in many environments, not just by isocyanate exposure. If this happens you will no longer be able to work with isocyanate paints – ever.

What happens when isocyanate gets on your skin?

In the past, doctors thought you had to breathe in isocyanates to develop isocyanate asthma, but it has recently been shown that in animals, skin exposure to isocyanate can “sensitize” the animals. That may turn out to be true for people too, so it is very important not to touch isocyanates. This can be difficult because even paint that is dry to the touch may still have the potential to “sensitize”, perhaps for as long as a month in some paints.

How can you tell if you have isocyanate asthma?

Asthma symptoms include labored breathing, shortness of breath, wheezing, coughing and tightness of the chest. Isocyanate asthma is difficult to tell from regular asthma unless there is a relationship between the attacks and when you were exposed to isocyanate. The part that makes it more confusing is that the asthma attacks can occur within a few minutes of the exposure or 4 or more hours later, or both.

Diagnosing asthma

First we need to confirm that you actually have asthma (often people are diagnosed with asthma when they really have bronchitis or a cough). In a true asthma attack, the airway constricts (closes up) as if to keep out the offending substance but keeps out air as well. Medication will re-open the airway and reverse the attack. If this shutting down and re-opening doesn’t happen, it is not considered to be asthma. If you develop asthma while working with isocyanates, you are likely to have isocyanate asthma and should see an occupational physician to determine whether or not you can continue to work around these chemicals.

Isocyanates are irritants

They irritate the respiratory tract or your skin just as many other substances in body shops do - like acids, ammonia, dusts and solvents. If you already have asthma and breathe in respiratory irritants, you may have an asthma attack. Even if you don’t have asthma, you might develop a cough or a catch in your throat after a day in the autobody shop, due to these irritants.