Bleary-eyed hay fever sufferers and pollen-sensitive citizens may soon be saved by a new wave of thinking from the United States.

US horticultural expert Thomas Ogren has flown to Canberra to further his mission of ridding our cities of asthma and allergic triggers.

Author of The Allergy Fighting Garden, US horticulturist Thomas Ogren. Credit:Jamila Toderas

The author and consultant has worked for several decades curating plant choices in schools, parks and city gardens to diminish the impact it can have on people's health.

The 70-year-old devised the Ogren Plan Allergy Scale (OPALS) used widely in nurseries in the United States and Europe to rank various plant species potential to cause reactions in humans.