Air Pollution Allergy: Symptoms, Causes & Treatment

An air pollution allergy means allergy symptoms that dirty air brings on or makes worse. Pollution is not an allergen; it irritates your nose and airways, so you react more strongly to real allergens such as pollen and dust mites. Indian cities often carry many times the safe level of fine dust in winter, enough to turn a mild seasonal allergy into weeks of sneezing and wheezing.

"Air pollution allergy" is an everyday name, not a medical diagnosis. Doctors split it into allergic rhinitis, for the nose, and asthma, for the airways. Either way, the trigger is a real allergen; dirty air only makes the reaction stronger.

Allergy symptoms begin within minutes of contact with your trigger. Irritation from dirty air builds up over hours. Common symptoms:

• Sneezing, often in bursts and worst in the morning
• Runny nose with clear, watery discharge
• Blocked nose that makes sleep difficult
• Itchy nose, throat or roof of the mouth
• Itchy, red, watery eyes
• Cough, often worse at night
• Wheezing or chest tightness, especially with asthma

Symptoms that only appear after a commute, or on hazy days, point to polluted air.

Two things work together: an allergen you are sensitive to, and dirty air.

Common allergens:

• Pollen from trees, grasses and weeds
• House dust mites in bedding and soft toys
• Mould in damp walls, bathrooms and air coolers
• Pet dander, flakes of skin from dogs and cats

Common pollutants:

• Traffic and diesel fumes, worst at rush hour
• Fine dust from roads, construction and stubble burning
• Smoke from cooking on wood, coal or dung
• Incense, mosquito coils and tobacco smoke

Delhi's average fine-particle levels were more than 15 times the safe limit in 2019. Across India, about 1 in 10 adults has allergic rhinitis, and close to 1 in 4 teenagers does.

Many people have both. Polluted air makes pollen season harder, because the two together irritate the nose more.

Think of the lining of your nose as a brick wall. Pollution loosens the mortar.

1. Cracks the wall: Diesel soot and fine particles damage the tight joins between cells, so pollen and dust slip through.
2. Adds fuel: The same particles switch on inflammation, leaving the nose swollen and blocked.
3. Raises the alarm: Your body makes more allergy antibody, so the same pollen sets off a bigger reaction.

That is why an identical pollen count can feel mild on a clear day and miserable in a smog spell.

• People with asthma or hay fever, whose airways are already sensitive
• Children, who breathe more air for their body weight
• Older adults, especially with heart or lung disease
• Outdoor workers such as traffic police and delivery riders

• Antihistamine tablets such as cetirizine and levocetirizine ease sneezing, itching and a runny nose. Older ones cause sleepiness.
• Steroid nasal sprays reduce swelling inside the nose and are generally safe as directed.
• Saline sprays and rinses just clean the nose.
• Decongestant nasal sprays and drops unblock the nose quickly. Do not use them past 3 days, or at all with high blood pressure, heart disease, an enlarged prostate or an MAOI antidepressant.
• Leukotriene tablets are prescribed only when other treatment is not enough. Tell your doctor about past anxiety or depression, and stop if your mood changes.
• Allergy shots or under-the-tongue drops are for symptoms that stay hard to control.

In India, cetirizine and levocetirizine are Schedule H drugs under the Drugs and Cosmetics Rules. They cannot legally be sold without a doctor's prescription.

Your doctor decides how much and how often, based on your age, symptoms, asthma and whether you are pregnant or breastfeeding.

Never increase the dose on your own. A bigger dose does not clear a blocked nose faster, but it does raise the risk of sleepiness and a dry mouth.

For children, ask a paediatrician. If someone takes too much, go to the nearest hospital with the strip or bottle.

Take it when you remember. If your next dose is close, skip the missed one. Never take two doses together.

If you keep missing doses, ask for a simpler schedule.

Antihistamine tablets ease sneezing and itching while the dose lasts, so they are taken when symptoms flare. Steroid nasal sprays calm swelling that builds slowly, so they work best used every day, including on good days. If daily use for a few weeks does not help, go back to your doctor.

Most people take allergy medicines without any trouble. When side effects happen, they are usually mild.

Common and mild:

• Sleepiness and a dry mouth, mostly with older antihistamines
• A blocked nose that gets worse after stopping a decongestant spray

Rare but serious - stop and get help:

• Swelling of the face, lips or tongue, or trouble breathing
• Anxiety, low mood or disturbing thoughts with leukotriene tablets

The sleepiness comes from older antihistamines; do not drive after taking one.

• Children under 6: no decongestant nasal sprays or drops, unless a doctor advises.
• Anyone with a past severe reaction to that medicine.
• Children: no adult tablets without a paediatrician's advice.
• Anyone told to avoid a specific ingredient, such as a dye or preservative.

These are different medicines with different rules, so read the leaflet.

Tell your doctor before taking any allergy medicine if you:

• are pregnant or breastfeeding
• have asthma (a worsening cough or wheeze needs a review)
• drive or operate machines for work
• have kidney or liver disease
• have high blood pressure, heart disease or an enlarged prostate (decongestants raise blood pressure)
• are over 65
• already take other medicines, including herbal ones

Tell your doctor about every medicine, supplement or home remedy you use. Keep alcohol low with a drowsy antihistamine; it worsens the sleepiness.

Treatment starts with what you breathe in:

• Check the air quality index before walks and outdoor work.
• Avoid rush hour on busy roads where you can.
• Keep windows closed on hazy days.
• Do not burn incense, coils or rubbish indoors, which adds fine particles.
• Cook with a chimney or exhaust fan.
• Dust with a damp cloth, and wash bedding in hot water.

No medicine cancels out dirty air; these steps lower what you breathe in.

Partly. They cut some particles, but proof that they prevent symptoms is weak.

A tight-fitting respirator, marked N95, KN95 or FFP2, filters fine particles, but real-world trials have not yet shown a clear drop in symptoms. Masks are not advised as a public health measure. Anyone with heart or lung disease should be careful, and no commercial respirator is designed for children, as far as was known in 2019.

Portable air purifiers cut indoor fine particles by 40% to 82%, though the health benefit is less certain. Ozone-producing models can irritate the lungs. Changing filters and closing windows cost less than a new machine.

Keep tablets and sprays cool and dry, away from sunlight and out of children's reach. Check the expiry date before each use.

Allergy treatment eases symptoms but does not fix the air. See a doctor quickly if you have:

• Severe breathlessness, or difficulty speaking or walking
• Chest tightness or wheezing that does not settle after your reliever inhaler
• A reliever inhaler that you need far more often than usual
• Swelling of the face, lips or tongue

For a severe asthma attack, call 112, or 108 for an ambulance. Do not drive yourself to hospital.

Dirty air does not create an allergy, but it makes one much harder to live with. The cheapest steps help most: time your outings, keep windows shut on bad days and stop burning things indoors.

Medicines work well when used correctly. Steroid nasal sprays need daily use, not just bad-day use, and antihistamines should come from a doctor.