Thanks for your question on Healthcare Magic.
I can understand your concern.
To prevent recurrent lung infections due to dust allergy
, you may should do following things.
1. Use air purifier in the home.
2. Always give mask to your son whenever he is outside home.
3. Give him regular respiratory vaccines like influenza
(yearly) and pneumococcal (5 yearly).
4. Warm water gargles and steam inhalation 4-5 times a day are Alsop good for you respiratory hygiene.
Don't worry, with above practice his chances of recurrent lung infections reduce significantly.
Hope I have solved your query. I will be happy to help you further. Wishing good health to your son. Thanks.