It may be contrary to conventional wisdom, but some people have more sick days in warmer months. This can make it more difficult to get outside and play. Getting in a game of soccer or baseball is great fun. Having fun with these activities can be decreased by seasonal allergies and illness.
Summer is a great time for travel. The world has many things to explore, and unfortunately there are pathogens that like to explore us. That's not something that we normally think about, but that how things like bird flu and SARS make the jump from their Asian origins to areas in North America and Europe.
In the case of allergies people have an immune system that is overreacting to stimulus in the environment. In some cases that is pollen, in others it's certain kinds of dust or chemicals such as exhaust fumes.
These things are not normally harmful, but the body reacts as if it does. Even though a bit of plant pollen may enter an airway or nasal passage, this does not really constitute a threat to our health. This is a manufactured threat by the body. Putting the immune system back in balance can fix many of these reactions.
The immune system can take some time to adapt as we transition from indoor to outdoor activities. The outdoor activities bring us in contact with new bacteria and viruses in addition to the common allergens.
One preventative measure to take in both of these cases is learning how to strengthen the immune system. This makes sense for fighting off viruses and bacteria, but how does this affect allergies? One mechanism for making a stronger immune system is to increase the amount of interferon in the body. This hormone can actually balance the immune system so that the body does not overreact to allergens.
There are several natural supplements available that can boost the immune system. It's important to investigate the claims on each to make sure that it not only works, but is safe for long term use. Some of the more reputable companies will offer reports on immune system health and make studies available for review.