Human Health and Disease

Lysozyme is an antibacterial enzyme present in body secretions such as tears, saliva, sweat and mucus.
It forms part of the physiological barriers of innate immunity.
It breaks the glycosidic bonds of the peptidoglycan (murein) layer of the bacterial cell wall.
With the cell wall damaged, the bacterial cell bursts by osmotic lysis.
It is most effective against Gram-positive bacteria, whose thick peptidoglycan layer is exposed; so it destroys certain types of bacteria, not all microbes.
Viruses and virus-infected cells have no peptidoglycan, and the cell wall of fungi is made of chitin, so lysozyme does not destroy them.
So lysozyme destroys certain types of bacteria.

Asthma is an allergic disorder in which the bronchi and bronchioles become inflamed and constricted, causing difficulty in breathing and wheezing.
Allergy is the exaggerated response of the immune system to certain antigens (allergens) present in the environment; IgE antibodies are produced and mast cells release histamine and serotonin.
Pollen grains of many species are common allergens and cause severe allergies and bronchial afflictions in some people, often leading to chronic respiratory disorders such as asthma and bronchitis.
Many plants shed large amounts of pollen in particular seasons, so the amount of pollen in the air rises in those seasons.
The seasonal increase in asthmatic attacks is therefore related to the inhalation of seasonal pollen (for example of Parthenium, the carrot grass).
So the answer is inhalation of seasonal pollen.

Sonography (ultrasound imaging) uses high frequency sound waves, far above the range of human hearing.
Ultrasound in the frequency range of 1 - 15 MHz is beamed into the body from a transducer.
The waves are reflected from the boundaries between tissues of different densities, and the echoes are converted into an image called a sonogram.
Lower frequencies in this range penetrate deeper, while higher frequencies give better resolution of structures near the surface.
The technique is safe because it does not use ionising radiation, so it is widely used to examine the foetus in the uterus and organs such as the kidney, gall bladder and heart.
So the frequency used is 1 - 15 MHz.