This is a randomized controlled human exposure crossover study, aims to explore the health benefits of indoor plants on cardiopulmonary system on adults.

The researchers will conduct a randomized cross-controlled trial involving 48 healthy adults in Hangzhou, China. These participants will be randomly assigned into two groups, each comprising 24 individuals. Each participant will undergo two separate exposures in an office setting: one exposure without any plants present, and another exposure with 34 to 38 potted plants. A washout period of at least 4 weeks will be implemented between the two exposures. Questionnaires, physical examinations and the collection of biological samples will be conducted prior to exposure and after exposure. In addition, the monitoring of negative air ion, air pollutants and noise exposure, as well as collection of environmental microbial samples, will be conducted on weekdays. Researchers will gather samples of blood, urine, nasal secretion, and exhaled breath condensate from participants.

Inclusion Criteria:

• Living in Hangzhou during the study period;
• Non-smoking, no history of alcohol or drug abuse;
• Staying indoors in daytime we required.

Exclusion Criteria:

• Current or ever smokers;
• Subjects with allergic disease, such as allergic rhinitis, allergic asthma, and atopy;
• Subjects with cardiovascular disease, such as congenital heart disease, pulmonary heart disease, and hypertension;
• Subjects with respiratory disease, such as asthma, chronic bronchitis, and chronic obstructive pulmonary disease;
• Subjects with chronic disease, such as diabetes, chronic hepatitis, and kidney disease;
• Subjects with a history of major surgery;
• Medication use or dietary supplements intake in recent two months;
• Unable to cooperate with follow-up.