Have your loved one wear a mask when outdoors and take otc meds. The mask appear to help keep pollen from entering the lungs..
I'd get allergy tested to see what you are allergic to, get the appropriate meds, not all over the ckunter meds work and you may need an inhaler. Wear a mask outside, don't drive with windows open and don't sleep with windows open. Once you figure out what you're allergic to and get appropriate meds you will feel better. It's possible your seasonal allergies are food related hence the suggestion of getting tested.
I love the outdoors and also have seasonal allergies. I find the following tips help. Air conditioning. I may go out to walk or garden. When I get in I remove my clothing and wash them, get in a shower and wash my hair and body to remove allergens. Also, as I am 74, I use my swiffer with the terry cloth mop head and spray my tub and walls with scrubbing bubbles and wash the tub and walls. Much easier than trying to reach and climbing ladders. Keeping dust down involves a schedule. I can’t do the whole house in a day like I used to so I work on vacuuming and dusting one room a day. The biggest help for allergies is to keep surfaces clean. That includes me. lol.
Our neurologist recommended Xyzal as safe to take with the dementia and seizure meds.
I agree with BobbieKay1. I wear a mask, hat, long sleeves, and pants when mowing the lawn, when I go indoors, all cloths go directly into the wash. I shower to get the allergens removed from my hair and body, and I throw the towels in the wash with my clothes. Also keeping my outside shoes in the laundry room and wearing shoes that are for indoor only. I find I often need to use nasal spray and OTC allergy medications.