Dear Doctor: I am bothered by certain scents, especially from candles. What causes it? And other than moving away from the source, is there anything I can do to combat this problem?

Dear Reader: When it comes to having an adverse reaction to the scents and fragrances that are routinely added to thousands of products, you are far from alone. About a decade ago, researchers found that more than 30% of the general American population considered scented products irritating. A similar 2016 study put that number at nearly 35%. Participants in both studies reported that even brief exposure to a fragranced product could result in a migraine headache; trigger an asthma attack or other respiratory difficulty; and cause dizziness, fatigue, problems concentrating, numbness, nausea and skin rash. Scented and perfumed items that caused these problems included the candles that you struggle with, as well as cleaning products, laundry soaps, personal care products, dryer sheets, trash can liners and, of course, perfumes, aftershaves and colognes.

Scented products – even those advertised as being natural, “green” or organic – emit a wide array of volatile compounds, including some considered to be hazardous pollutants. We notice their scent when airborne molecules enter the nose and activate the complex network of receptor sites and nerves that translate a chemical structure into a specific smell. People who have an adverse reaction to these added scents are said to have a chemical sensitivity. Some are bothered by one or two types of chemicals, while others struggle with multiple sensitivities.

Unfortunately, it’s virtually impossible to identify exactly which compounds are at fault. That’s because, unlike the ingredients of a product, fragrance is considered to be a trade secret. Manufacturers aren’t required to disclose the specific chemicals they use to scent their products.

Awareness of the problem is growing. Some states are proposing laws to require manufacturers to disclose all chemical ingredients on their packaging. A 2016 legal ruling allowed multiple chemical sensitivity to be categorized as a disability, which lets – or requires – employers enforce fragrance-free policies when an employee has a condition that substantially limits one or more life activities. So if you have a minor allergy to a fragrance that causes a runny nose, you are not entitled to an accommodation, but if the allergy interferes with your breathing, you are.

Meanwhile, for the general population – and in answer to your final question – avoidance is the only real solution. And again, when you walk away to avoid the effects of a scented candle, you’re not alone. Studies have found that one-fifth of people will exit a store to avoid the headache or stuffy nose that airborne fragrances can cause. Fully 15% of people report missing work due to sensitivity to added scents or fragrances. Some even avoid washing their hands in a public bathroom that offers only scented soap.

You can learn more about the issue from the Chemical Sensitivity Foundation at chemicalsensitivityfoundation.org.

Send your questions to askthedoctors@mednet.ucla.edu.