Asthma Irritants: Smoke, Pollutants, Perfumes, Chemicals, and More

Reviewed by: HU Medical Review Board | Last Reviewed: May 2016. | Last updated: October 2020

“Irritant” is a broad category that includes things such as cigarette smoke, pollutants, strong perfumes, cleaning products, paint fumes, dust, and exhaust fumes. Irritants are different from allergens because they do not set off the immune system. Irritants damage the lining of the airways, which triggers asthma symptoms.1

People living in North America spend nearly 90 percent of their time indoors.2 The indoor air in homes and workplaces may contain a number of irritants. Studies have shown that repeated exposure to low-level irritants can cause or aggravate asthma.1 One-time exposure to high levels of an irritant can also cause breathing problems.1

Asthma irritants in the home

Irritants in the home come from a variety of sources. They include wood-burning stoves and fireplaces, kerosene heaters, cleaning supplies, smoke from cooking, perfumes, and tobacco products.3 Inside moisture may also cause carpeting and vinyl floors to release irritating chemicals.4

Newly constructed or renovated homes often contain irritants from flooring and carpets, particleboard, wall coverings, and paint.3

Common irritants in the home and their sources include:3

  • Nitrogen dioxide (NO2) from unvented stoves, space heaters, and poorly vented furnaces and fireplaces. Nitrogen dioxide irritates the eyes, nose, throat, and airways.5 Brief exposure to high levels of nitrogen dioxide has been linked with airway reactions and asthma attacks.4 Low-level exposure has been linked to increased airway sensitivity in people with asthma and an increased risk of colds in young children.5
  • Formaldehyde from plywood, particle board, paints, varnishes, floor finishes, new furniture, and cigarette smoke. Formaldehyde and asthma have been linked in several studies, but the exact effects are unknown.4,6 Formaldehyde may cause chest tightness, wheezing, nose bleeds, and burning or tingling in the eyes, nose, and throat.5 One study showed that breathing in formaldehyde did not affect lung function directly, but it did make people react more strongly to dust mite allergens.4 Other studies have shown that formaldehyde increase the risk of developing asthma.6
  • Volatile organic compounds (VOCs) from dry-cleaned clothing, room deodorizers, cleaning sprays, wet paint, new carpet, and cigarette smoke. Volatile organic compounds (VOCs) irritate the eyes and upper respiratory tract, causing runny and stuffy nose, rash, itching, headache, nausea, vomiting, and shortness of breath.5 One study found that VOCs in the home increase the risk of developing asthma 1.6-fold.7 However, in people who already have asthma, it is not known whether VOCs cause asthma attacks.4

How many homes have asthma irritants?

About 35 percent of the homes in the United States have a gas stove, which produces nitrogen dioxide and other irritants.8 One study found that children living in a home with a gas stove have a 42 percent increased risk of developing asthma symptoms.9 Another study shows that children living in multi-family housing who are exposed to gas stoves are 2.3 times more likely to wheeze than children without a gas stove. Children exposed to gas stoves are also 4.3 times more likely to have chest tightness.10

About 10 to 20 percent of the general US population is hypersensitive to formaldehyde.5 All homes have some amount of formaldehyde.9 Homes built after 1990 are better insulated, so less air moves in and out of the home. This reduction of airflow can cause formaldehyde to remain in the home’s air longer.11 Traditionally constructed stand-alone homes have lower levels of formaldehyde than manufactured homes.9

VOC levels are 2 to 5 times higher inside than outside.10

Reduce exposure to asthma irritants at home?

  • Use ventilation when cooking with a gas stove.11
  • Open the flue when using the fireplace.10
  • Do not use room deodorizers, perfumes, or strong-smelling chemical sprays.2
  • Choose solid hardwood flooring and furniture.2
  • Increase ventilation in the home.2
  • Wait a few days to bring recently dry-cleaned clothing into the house.2
  • Do not allow smoking in the home.
  • Follow the instructions for using cleaners, paints, paint strippers, and similar products safely.10
  • Buy only what you need when it comes to paint, kerosene, etc.10 Safely discard any leftover products.
  • Do not idle the car in the garage.10
  • Use air conditioners and dehumidifiers to reduce indoor humidity.10

Workplace irritants

Irritant-induced asthma is a type of work-related asthma.
Common workplace irritants include:12

  • Acids
  • Ammonia
  • Calcium oxide, which is also known as quicklime and used in the manufacturing of cement, paper, and high-grade steel
  • Cement
  • Chlorine
  • Cleaning agents
  • Construction dusts
  • Diesel exhaust
  • Dinitrogen tetroxide, which is most commonly used in rocket propellants
  • Farming barn dusts
  • Hydrazine, which is often used in plastics, coatings, varnish, and adhesives
  • Isocyanates, which are chemicals that are widely used in painting, construction, and upholstery manufacturing industries
  • Metam sodium, which is used as an herbicide, pesticide, fumigant, and fungicide
  • Perchlorethylene, which is a liquid primarily used for dry cleaning fabrics and degreasing metals
  • Solvents
  • Spray paint
  • Sulphur dioxide, which is a gas that is often used as a food preservative, disinfectant, and refrigerant
  • Swine confinement facilities
  • Tobacco smoke
  • Uranium hexafluoride, which is a chemical compound used in uranium processing
  • Welding fumes
  • World Trade Center exposure

People who are regularly exposed to these irritants on the job have a higher risk of asthma. This includes those employed as cleaners, nurses, textile workers, hog farmers, poultry workers, and people who work in aluminum smelters.1 Another term for irritant-induced asthma is “reactive airways dysfunction syndrome,” which is a severe form.1

In some cases, there is a clear relationship between exposure to high levels of an irritant and asthma symptoms. Examples are accidental chlorine spills or fire smoke inhalation.13 Another example is the caustic dust and toxic pollutants left by the collapse of the World Trade Center. About 17 percent of first responders have developed irritant-induced asthma.14 One study also found that first responders exposed to these irritants experience asthma at more than twice the rate of the general US population.14

However, low-level exposure to irritants is common in many jobs.14 It can be difficult to identify which irritants are causing respiratory symptoms. Safety Data Sheets have information about the risks and safe handling of chemical products. The Safety Data Sheets will state whether a chemical is known to irritate the airways. These documents may be helpful in identifying potential workplace irritants.

How common is workplace exposure to asthma irritants?

The Occupational Safety and Health Administration (OSHA) estimates that about 11 million US workers are exposed to at least one known irritant in their workplace.16 One survey found that among US adults with asthma, 28 percent reported that they were regularly exposed to workplace irritants such as vapors, gas, dust, or fumes.17 It is estimated that work-related asthma accounts for 15 to 33 percent of adult asthma cases.18

Much less is known about the frequency of irritant-induced asthma. One study from Estonia showed that 17.4 percent of workers were exposed to low or moderate levels of irritants.19 In this study, professional cleaners were twice as likely to have asthma as people working administrative or service jobs.14

How do I reduce my exposure to irritants at work?

Steps to reduce your exposure to workplace irritants could include:13

  • Switching tasks or jobs
  • Improving workplace ventilation
  • Use of a fitted respirator
  • Closing off the source of the irritant

Procedures should be in place to minimize exposure in the event of an accident. These measures may include:1,12

  • Worker education on best safety practices
  • Good procedures for containment and ventilation
  • Plans for evacuating workers

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