How Smog Can Worsen Asthma and Grass Allergy in Summer

Published: July 12, 2016

Q. My asthma is always harder to control in summer. I have a grass allergy, and smog affects me more when it’s hot. Do the two triggers somehow act together to increase chances of an attack? How can I keep control?

Dr. Bassett: Smog contains air contaminants, such as ground-level ozone, which researchers have associated with a rise in allergy symptoms and asthma risk. But according to a study from Germany, these pollutants may also have the power to supercharge some airborne allergens.

The scientists found that ground-level ozone and auto exhaust may set off chemical changes in certain pollens that could increase their allergenic potency.

Smog, Pollen Combo Effect

In summer, both grass pollen and smog levels tend to be highest, providing the potential “double whammy” effect you may be experiencing.

Protective strategies include curtailing outdoor activities on high pollen count and pollution days, and pre-treating with prescribed allergy and asthma medications before heading out.

And don’t ignore your indoor air, which the Environmental Protection Agency (EPA) states may hold more pollutants than outdoor air. Consider installing HEPA filters in your air conditioning system or getting portable units.

Also helpful are certain houseplants that are shown to help clean the air. For a list of top indoor air “scrubbers,” click here.

Dr. Clifford Bassett, allergist and asthma specialist, is the Medical Director of Allergy & Asthma Care of New York (; Twitter @allergyreliefny). He is on the faculty of NYU School of Medicine and Weill Cornell Medical College in New York City and is also the author of The New Allergy Solution: Supercharge Resistance, Slash Medication, Stop Suffering.

*For more on the study referenced see this page.

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