Chemicals and asthma

  • Chemicals sign - large Most of the reactions that people say they have to chemicals are not allergic reactions. However, people with asthma do have sensitive airways so some chemicals may cause asthma symptoms; these are called irritants. Other chemicals, if there is exposure to them over a period of time, may lead to the development of asthma. These are called sensitisers.

    For information about sensitising chemicals, which are usually encountered in the workplace, see Occupational Asthma.

    Inhaled chemicals
    • Formaldehyde gas which may be emitted from wood-based panels, furniture, glues, dyes, paints and cigarettes has a sharp smell. It can irritate the eyes and airways. Symptoms are temporary depending on the length and strength of exposure.
    • Nitrogen dioxide can worsen asthma symptoms with high exposure. The main indoor source of this comes from unflued gas appliances (e.g. heaters). Outdoor exposure comes mainly from the burning of coal and oil in power stations and from motor vehicle emissions.
    • Volatile organic compounds (also called VOCs) come from some synthetic and natural materials such as floor coverings, furniture, cleaning agents and products such as paints, adhesives and sealants.  They can cause irritation of the nose, throat and airways. These often occur when floor coverings, paint, or furniture is new, so they can sometimes be avoided by staying away from the area for a few days, and ensuring it is well ventilated.
    Other chemicals
    • Sulphur dioxide is used as a preservative in some foods (additive number 220–228). This may cause asthma symptoms in some people with asthma. Sulphur dioxide is also formed when coal and oil are burned so living close to power stations and smelters may sometimes produce wheezing, chest tightness and shortness of breath.
    • Aspirin: up to 11% of adults and 2% of children need to be cautious about taking aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) as they can cause asthma symptoms. Aspirin/NSAID-intolerant asthma (also known as aspirin-sensitive asthma) is a distinct type of asthma where symptoms occur 1–3 hours after taking this type of medication. See our asthma and pain relief section for more information.

    Rarely, food chemicals may trigger asthma in some individuals although in most cases it is difficult to demonstrate this. For more information about food additives, go to our food and asthma page.

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