Smoking, vaping and air quality: what impact on allergy and asthma?

In someone with asthma, smoking is associated with more difficult control, more severe exacerbations, more hospital admissions and faster decline in lung function. The response to corticosteroids may also be poorer.

Second-hand smoke is particularly important in children. Prenatal and postnatal exposure increases the risk of wheezing and asthma; in people who already have asthma, it is associated with poorer control.

Tobacco smoke may cause or worsen nasal symptoms. This does not necessarily mean an IgE allergy to tobacco: many symptoms result from non-allergic inflammation or irritation of the nasal lining.

Pollution and pollen do not always simply add together: they may also interact. Some pollutants can alter the airway barrier, increase inflammation and modify pollen grains or their particles. Mechanisms vary with the pollutant, pollen and weather.

• Check local alerts or indices if you know you are sensitive to pollution.
• Where possible, avoid intense exercise immediately next to heavy traffic during a major pollution episode.
• Adjust the time or location of activity instead of routinely stopping exercise.
• Continue maintenance asthma treatment and follow your action plan.
• Seek medical advice if asthma control worsens.

Volatile organic compounds (VOCs) are substances that readily enter indoor air. Sources include paint, varnish, adhesives, new furniture and materials, solvents, fragrances, air fresheners, household products, tobacco smoke and some forms of combustion.

VOCs are not allergens. They are generally regarded mainly as airway pollutants or irritants. Formaldehyde is one important indoor-air compound.

Someone may genuinely have a skin contact allergy to a fragrance, causing eczema that is investigated with patch tests. However, when a smell immediately triggers a blocked nose, cough, breathing discomfort or headache, the mechanism is not necessarily allergic. A strong smell may cause symptoms through irritation or hyperreactivity.

Burning candles release particles and VOCs; emissions depend on the wax, wick, fragrance, combustion quality, duration and ventilation. There is no evidence that occasionally lighting a candle in a ventilated room causes an allergy.

For people with asthma who are sensitive to smells or smoke. Limit repeated combustion, avoid using many candles, ventilate and stop exposure if it triggers symptoms. Use the same caution with incense, which may release large amounts of particles.

Regular ventilation helps remove indoor pollutants and VOCs. If you are highly allergic to pollen or outdoor pollution is very high, adjust the time of ventilation to outdoor conditions where possible.

An air purifier never replaces removal of the source. Before buying one: keep the home smoke-free, address damp or mould, provide effective ventilation and reduce emitting sources. HEPA filters may reduce some airborne particles, but clinical benefit depends on the situation, device airflow, room volume and actual exposure.

Order of priorities. Remove or reduce the source where possible → ventilate → address damp or mould → then consider filtration if it meets a specific need.

Not all houseplants are allergens. However, Ficus benjamina is a recognised respiratory allergen. Its plant latex contains allergenic proteins, and allergens may be present on leaves and in dust around the plant. Cases of rhinoconjunctivitis, asthma and hives have been demonstrated.

Do not remove it routinely. This does not mean every allergic patient must discard every Ficus. Consider it particularly when unexplained symptoms persist at home or work, symptoms occur near the Ficus or while handling it, and improve away from the exposure.

Cross-reactions between Ficus benjamina and Hevea latex have been described in some patients. Ficus-fruit syndrome, particularly involving fig, has also been reported. However, Ficus allergy does not automatically mean latex allergy or allergy to every fruit.

For a few days, note where symptoms occur, at what time, after which exposure, how long afterwards, and whether they disappear away from the suspected place or source.

No tobacco smoke in the environment, avoid vaping, limit major airway pollutants and continue appropriate treatment.