A) The source is probably not valid because it is based on an opinion.
He or she that wrote it did not go into a lab and see if the resources are true its just based on what he thinks it is.
Once a year or possibly for a physical when you are doing a sport or camp. Hope this helps!
Explanation:
Environmental physician is most likely to study the effects of air pollution on asthma.Environmental Physician focuses on the causes of disease in an environmental context.They not only study about air pollution but also ozone depletion and its effects on health, global warming etc
