Recently, air pollution by particlate matter (PM) including PM2.5 (less than 2.5 micron in diameter) and ultrafine particle (UFP: less than 0.1 micron in diameter) is raising important issue for cardiovascular and respiratory disease in Japan. In western Japan, Asian dust (yellow sand) flying in the early spring is affecting human daily life. Moreover, volcanic ashes also influence human activity that is living around the volcanic area. Increased PMs is known to be usually caused by industrial activities and/or natural disasters. Acute exposure has been linked to a range of adverse cardiovascular events, including hospital admissions with angina, myocardial infarction, and heart failure. Long-term exposure is thought to promote the atherosclerosis and impair cardiovascular risk factors. Recent experimental and epidemiologic studies show that PM2.5 is able to reach the small airways and terminal alveoli, and UFP can also be translocated directly into the systemic circulation, which lead to the releases of immunological, oxidative and inflammatory mediators, autonomic nervous system imbalance, and endothelia dysfunction resulting in impairment of cardiovascular risk factor and diseases. In this review, we would like to discuss the influence of PM2.5 on cardiovascular disease.

Objectives: Bathing in a bathtub made of hinoki cypress may promote relaxation. This study focuses on changes in autonomic nervous system function, and emotional assessments of individuals who bathed in a hinoki cypress bathtub.

Methods: All 16 study participants bathed twice, as interventions in this study. The baths consisted of bathing in a hinoki cypress bathtub and in a modular bathtub as the control experiment. During the study, participants wore a holter monitor. Before and after bathing, saliva samples were collected for cortisol measurement, and participants underwent a subjective emotional assessment, the Mood Check List-Short Form.2 (MCL-S.2). After bathing, an additional subjective emotional assessment, the Visual Analog Scale (VAS), was performed.

Results and Discussion: The emotional assessments in the MCL-S.2 indicated a significant increase in positive emotional scores (“pleasantness”) after bathing in a hinoki cypress bathtub. The VAS scores showed a significant decrease in the “feeling of fatigue” after bathing in a hinoki cypress bathtub, compared to bathing in a modular bathtub. These results suggest that study participants who bathed in a hinoki cypress bathtub experienced positive effects, and decreased feelings of fatigue. The salivary cortisol concentration decreased significantly after bathing in the hinoki cypress bathtub and in the modular bathtub. For both the hinoki cypress bathtub and the modular bathtub, the high frequency (√HF) values collected with the holter monitor after bathing, were higher than the √HF values collected prior to bathing. The results suggest that bathing in water temperatures of 38-39°C for 15 min enhances relaxation, and has a positive effect on the human body.

Background: Hot spring inhalation and rock bathing are widely practiced in Europe, and immersion in water up to the shoulders is popular in Japanese balneotherapy. We designed a combination therapy of steam rock bathing and immersion in an open-air hot spring pool for allergic rhinitis.

Methods: Data were obtained by anonymous questionnaires from 19 participants with perennial allergic rhinitis who underwent the combination therapy for several days during the spring-pollen season. The participants immersed themselves in a sitting position in Saiboku hot spring water (sodium salt hot spring) at 41°C up to the shoulder level for 10 min in the open-air and then lay on a floor paved with small rocks in a supine position for 20 min in a room filled with the steam from hot springs, then immersed themselves again in the hot spring water for 10 min, and finally rested and sat on a chair for 20 min in a comfortable room. The hot spring water circulated through tubes with small holes that were embedded under the floor, which was paved with small rocks consisting of tourmaline and lime stones. Steam from the hot spring water penetrated through the floor and vaporized in the room. The rock bathing room was 40°C in temperature and 75% in humidity.

Results: Clinical symptoms were alleviated in 17 of 19 participants. Watery rhinorrhea, eye itching, sneeze, and sore throat were improved in 100%, 75%, 40%, and 100% of the participants, respectively, compared with symptoms during the previous several years. No adverse effects were observed in any participants.

Conclusion: Steam rock bathing, combined with immersion in an open-air hot spring pool, is useful in ameliorating the focal and systemic symptoms of allergic rhinitis.

Purpose: Bathing habits are said to be affected by the country of residence. We investigated and compared bathing habits between Japanese living in Kyoto and Japanese Americans living in Los Angeles.

Methods: 488 subjects living in Kyoto (Japanese) and 539 subjects living in Los Angeles (Japanese Americans) were enrolled. The survey items for bathing habits were as follows: frequency (times per week) and time (morning, afternoon, evening) of taking baths and showers, other styles of bathing, and bathing duration (both baths and showers). We performed a simple tabulation and cross tabulation, calculated 95% confidential intervals by simple tabulation, and compared the results using chi-square analysis. The survey was conducted in Los Angeles in October 2010 and in Kyoto in December 2013.

Results: The percentage of subjects who took baths was 92.8% for Japanese and 56.0% for Japanese Americans. The frequency of taking a bath was 36.8 points higher for Japanese compared with Japanese Americans. The percentage of subjects who took showers was 71.7% for Japanese and 82.6% for Japanese Americans. The frequency of taking a shower was 10.9 points higher for Japanese Americans compared with Japanese. The most common response for frequency of bathing was “every day”, followed by “every other day” in both groups. The most common response for the time of taking a bath was “evening” in both groups. Among Japanese Americans, 21.8% took baths in the “morning”. Most Japanese indicated they took a shower “less than once a week” (48.0%), whereas most Japanese Americans took a shower “every day” (78%). The timing of taking a shower was in the “evening” for most Japanese, but in the “morning” or “evening” for most Japanese Americans. The most common response for bathing duration (both baths and showers) was “26-30 min” among Japanese and “6-10 min” among Japanese Americans.

Discussion: For Japanese Americans, the purpose of bathing was suggested to be cleaning the body since their main style of bathing was taking showers of a short duration in the morning or evening. On the other hand, for Japanese, the purpose of bathing was thought to be cleaning and healing the body, but also maintaining health since their main style of bathing was taking baths of a long duration in the evening. We speculate that the country of residence affects bathing habits and that there are differences among people of the same race living in different countries.

Conclusion: Bathing habits such as bathing style, the time of bathing and bathing duration were different between Japanese and Japanese Americans.