We measured an indoor nitrogen dioxide (NO₂) concentration in Sendai using a passive analytical chip combining a porous glass and the Salzman's reagent, during the summer and the winter in 2016. The analytical chip was found to work cumulatively until it's absorbance at 525 nm reaches to 4.0. The analytical chip is easy to operate, and we can measure the NO₂ concentration by only leaving to stand then at arbitrary place and arbitrary time interval. We calculated the NO₂ concentration from the absorbance changes at 525 nm of the analytical chip before and after exposure to an indoor air.
We measured the 67 and 95 households in summer and winter, respectively, and the obtained NO₂ average concentration were 8ppb and 92ppb in summer and winter, respectively. In the winter, households that were exceeding WHO's guideline (106ppb) and school environmental health standard of Japan (60ppb) were 35.8% and 49.5%, respectively. On the other hand, there were no households that exceeded the guideline and standard values in the summer. We also considered the relationship between the obtained NO₂ concentration and the actual conditions that became evident from the questionnaire survey. Regarding the effect of 24 hours continuous ventilation system, it was found that the NO₂ average concentration were 64ppb and 94ppb for with and without the ventilation system, respectively. The actual indoor NO₂ concentration was found to be complex and it was very difficult to estimate the NO₂ concentration from the household's conditions such as ventilation system and type of cooking device, etc. Therefore, in order to improve an air quality and to maintain a healthy living environment, residents should select an effective method based on the themselves' measurement of air pollutants such as NO₂. The develop analytical chip would be an effective tool for the residents' measurement.

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Many workplaces are indoors, and workers share a common time in each workplace. What is concerned about microbial contamination in the workplace is the outbreak of the ill person, and there are various problems ranging from infections to health effects caused by buildings. Tuberculosis, influenza, rubella, etc. can be transmitted from person to person, but legionellosis and fungal allergies are caused by microorganisms released from the equipment into the environment. The generation of microorganisms from equipment is also caused by human factors such as poor maintenance of cooling towers and air conditioning equipment, and insufficient cleaning of humidifiers. Countermeasures include cleaning the facilities and equipment that are the source of generation and continuous injection of drugs, but cost performance is also important for companies.
On the other hand, outbreaks in the workplace affect the economic foundation and social responsibility of companies, and infection prevention measures including infection route measures are more important than the source measures. Article 68 of the Occupational Safety and Health Act stipulates a “prohibition of employment” to prevent the spread of infection in the workplace. However, seasonal influenza, measles and rubella are not subject to work prohibition, so infections with these diseases are important not only for individuals but also for companies. In the manufacturing industry, hypersensitivity pneumonia due to exposure to water-soluble metalworking fluids have attracted attention, and it is thought to be caused by mixed exposure including not only mineral oil and surfactants but also microorganisms that grow in the metalworking fluids.
In order to prevent health problems caused by microorganisms in the workplace, maintaining a good workplace environment will become even more important in the future, and it will be necessary to consider work environment management including microorganisms.

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