If the disease is communicable, it is contagious. If it is airborne, it is transferred through the air, as opposed to physical touch or blood-borne. Being in a confined space, such as an ambulance, with an airborne communicable disease means you have most definitely been exposed to it.
The blood levels should check for the acetylsalicylic acid because aspirin is a blood thinner. I know because I take only a baby aspirin for a condition I have and I still bleed easily.
If you live near a neighborhood that has lots of trees it can help with air so you can breath so it is healthy and your environment has trees