Too much or too little humidity can have a profound impact on human health. From respiratory illnesses to skin problems to the worsening of chronic diseases, there is a complex correlation between humidity and disease. We will systematically analyse the health risks of different humidity environments and provide scientific coping strategies.

Health risks of high humidity

1. Respiratory diseases

Breeding of moulds and mites

When humidity is >60%, moulds and dust mites multiply rapidly, and their metabolites (e.g., spores, faeces) can trigger allergies, asthma and chronic rhinitis.

Research data: WHO states that about 40% of asthma cases worldwide are related to indoor mould exposure.

Bacterial and Viral Transmission

High humidity (especially with high temperatures) favours the survival of influenza viruses and streptococcus bacteria, increasing the risk of respiratory infections.

2. Joint pain and rheumatic diseases

Cold and humid environments can increase the viscosity of synovial fluid in the joints, which can aggravate pain in arthritis patients (in Chinese medicine, ‘dampness enters the bones’).

Clinical observation: Rheumatoid arthritis consultation rate rises by 20% to 30% during the rainy season.

3. Skin diseases and fungal infections

Long-term humidity can easily cause eczema, ringworm (such as foot fungus), sweat herpes.

Principle: skin barrier function is damaged, fungi (such as Candida albicans) reproduction accelerated.

Health problems of low humidity

1. Respiratory mucous membrane damage

When the humidity is <40%, the mucous membrane of nasopharynx and trachea is dry, resulting in:

susceptibility to infection: viruses (e.g. influenza) are more likely to adhere to the dry mucosa.

Chronic cough: mucosal cilia have reduced motility and are less able to clear foreign bodies.

2. Skin and eye problems

High incidence of dry dermatitis and pruritus.

Increased risk of dry eye (especially for people who use air-conditioning/heating for a long time).

3. Immune system burden

Dry environment, the human immunoglobulin A (IgA) secretion is reduced, the local immune system.

Strategies for scientific humidity regulation

1. Monitoring and selection of tools

Hygrometer: real-time monitoring (recommended electronic models, error <5%).

Dehumidifying equipment:

Dehumidifier (suitable for humidity > 70% environment).

Air conditioner dehumidification mode (short-term application, but may be overly dry).

Humidifying equipment:

Ultrasonic humidifier (need to use pure water to avoid PM2.5 pollution).

Evaporative humidifier (safer, suitable for children's room).

2. Natural adjustment method

High humidity environment:

Open windows for ventilation (choose the lower humidity period in the afternoon).

Place moisture-absorbing materials (e.g. bamboo charcoal, silica gel).

Low humidity environment:

Drying clothes indoors, placing water bowls.

Planting plants with strong transpiration (e.g., asters, Boston ferns).

3. Adjustment of living habits

High humidity: Avoid drying clothes indoors, use a dryer.

When humidity is low: Drink plenty of water and use moisturising skin care products.

Conclusion

Humidity is an ‘invisible variable’ that affects health. Reasonable regulation can significantly reduce the risk of disease. It is recommended to dynamically adjust the indoor humidity according to the regional climate and individual health condition, and if necessary, combine it with medical advice (e.g. asthma patients need strict humidity control). The development of technology (e.g. intelligent humidity control system) may provide more accurate solutions for health management in the future.

Extended reflection: In the context of climate change, where extreme humidity events (e.g. floods, droughts) are increasing, how can humidity in human habitats be improved through building design and public policy? This question deserves further exploration.