To avoid becoming sick and stay healthy in a foreign country, it is important to learn about local-common health problems as well as preventions. In Japan, summer heat and high humidity can lead to possible food poisoning, fatigue and heat stroke. In spring and fall, many people suffer from rhinitis and itchy eyes caused by pollen, especially Japanese cedar pollen.

Due to a hot and humid climate that gives favorable conditions to bacteria, food poisoning is a common health issue during summer in Japan. Avoid eating food that has been sitting in room temperatures for a long time. It is also helpful to sterilize cutting boards and kitchen towels more often.

Summers can be surprisingly severe especially in Tokyo and other urban areas due to the "heat island" phenomenon, which is caused by, among others, exhaust heat from air conditioners' outdoor units and heat reflection on asphalt-covered ground. To maintain your energy levels during the summer heat it is recommended to drink plenty of water, to avoid excess intake of cold drinks, to get adequate sleep, and to eat nutritious meals. Sprinkling water around the house in the evening is also helpful to cool things down.

If you spend a long time in very hot conditions, you may get dehydrated, which could develop into a life threatening condition. To avoid such heat stroke during summer, it is important to take plenty of water, to use sunshades such as hats and/or parasols when you go outside, to avoid staying too long under the sun, and to avoid hard outdoor exercise during the daytime.

Many people in Japan today are suffering from pollinosis (hay fever). It is an allergic reaction to the pollen of certain plants and causes symptoms including sneezing, a runny nose, and itchy eyes.

In Japan, as many as about 60 types of plants are known to cause pollen allergy. In Tokyo, common allergy-causing plants and their pollen seasons are as follows:

• Japanese cedar sugi (February - April)
• Japanese cypress hinoki (mid March - early May)
• Rice plant ine (May - mid July / mid August - mid October)
• Ragweed butakusa (mid August - October)
• Artemisia yomogi (mid August - October)

People who are not currently affected by pollen may later develop allergic reactions as a result of constantly inhaling pollen in their daily lives. Japanese cedar (sugi) allergy is most common. In Tokyo, about one in 3.5 people is believed to suffer from sugi allergy.
During the sugi pollen season (February - April), weather forecasts usually provide information about the possible amount of pollen in the air. To avoid becoming allergic to pollen, or to reduce the symptoms, it is important to use masks and/or special eyeglasses to effectively block pollen from getting into your body as much as possible.
If you know you are allergic to pollen, it is advised to get prescriptions for appropriate medication before pollen levels get high. Visit a doctor two weeks before the season starts at the very latest. Ask your doctor if you need to continue taking the medication throughout the season after the symptoms ease; they may quickly come back and be worse if you stop taking the medication in the middle of the season.

New influenza has marked antigenic differences from seasonal influenza, and since most people lack immunity to it, its rapid spread is known to pose a major threat to safety and health.

The anti-flu medication Tamiflu has proven effective against the 2009 strain of new influenza, reducing symptoms and allowing a smooth recovery for sufferers of the flu.

Tips to prevent the infection and spread of new influenza

Frequent hand washing and gargling as well as proper cough manners are believed to be effective for protecting yourself as well as others around you from the spread and infection of influenza.

What are cough manners?

Wear a cold mask if you are suffering from coughing and sneezing.
Cover your mouth and nose with tissue paper or something similar when you cough or sneeze.
Turn your face away from other people when you cough or sneeze.