Swimming Skin and Immunity: The Physiological Effects of Long-Term Chlorinated Water Exposure

Introduction

The disinfectants used in swimming pools—primarily chlorine or its derivative sodium hypochlorite—are an indispensable public health tool for modern pools. It is chlorine that kills bacteria, viruses, and fungi in the water, allowing millions of people to safely share the same body of water. However, while chlorine protects health, it also produces a series of physiological effects on the skin, eyes, respiratory system, and immune system of long-term swimmers. For Taiwanese swimming enthusiasts who swim several times a week, understanding these effects and taking appropriate precautions is an important issue for maintaining long-term health.

The Chemistry of Chlorinated Water: What Are “Chloramines”

When chlorine is added to water, it reacts with organic matter in the water (sweat, urea, and skin proteins secreted by the human body) to form a class of compounds called “chloramines.” Trichloramine is the most irritating type and is the main source of that “chlorine smell” in pools—ironically, the stronger the chlorine smell, the poorer the water quality (more organic contaminants), rather than an excess of disinfectant.

The Skin: The Most Direct Victim of Swimmers

The skin is the largest organ of the human body and the tissue with the largest surface area in direct contact with chlorinated water.

Main effects of chlorinated water on the skin:

Taiwan-specific situation: Taiwan’s climate is humid, so skin moisture evaporation is relatively slow, and post-swim skin dryness may be less severe than in drier climates. However, dryness remains significant for swimmers in air-conditioned environments (such as indoor pools).

Effects on the Eyes and Respiratory System

Eyes:
Hypochlorous acid reacts with proteins in tears, disrupting the protective tear film on the corneal surface, leading to:

• Temporary eye stinging and redness after swimming (caused by volatile trichloramine irritating the conjunctiva)
• Chronic dry eye syndrome in long-term, high-frequency swimmers
• Direct exposure of the eyes to chlorinated water (without goggles) increases the risk of corneal epithelial damage and infection

Respiratory system:
The respiratory effects on competitive swimmers (especially those who train long hours in indoor pools) are a topic worthy of attention:

• Trichloramine volatilizes above the water surface; prolonged inhalation while at poolside or during swimming may irritate the bronchi
• Studies have found that the prevalence of asthma among indoor swimmers is higher than in the general population
• Known mechanism: chloramines damage bronchial epithelial cells, increase allergen penetration, and trigger airway allergic responses
• There are also cases among Taiwanese track and field athletes who switched events due to this issue after competitive swimming

Effects on the Immune System

The immune effects of chloramines have been a focus of recent research. Current main findings:

Potential pro-inflammatory effects:
After entering the body, chloramines may be absorbed through the skin or inhaled through the respiratory tract, inducing mild systemic inflammatory responses and increasing levels of certain inflammatory cytokines.

Implications for sensitive populations:

• People with atopic dermatitis or allergic constitutions are more likely to have dermatitis triggered by chlorinated water
• Those with a history of asthma should be especially cautious when swimming in indoor pools with high chlorine concentrations

A balanced perspective:
The physical activity of swimming itself has an overall positive effect on the immune system (moderate exercise enhances immune function). The mild negative effects of chlorinated water are usually far outweighed by the health benefits of swimming. For most healthy swimmers, the effects of chlorine are manageable and should not be a reason to give up swimming.

Chemical Damage to Hair

The effects of chlorinated water on hair (composed of keratin) are similar to those on the skin:

• Chlorine disrupts the disulfide bonds in hair keratin, making strands brittle and dull
• Hair color lightening (especially noticeable for those with dyed hair)
• Green hair in pools: not directly caused by chlorine, but by copper ions in the water binding to hair proteins

Practical Recommendations

1. Shower before swimming and apply a waterproof barrier: Rinse skin and hair with fresh water before entering the pool so pores absorb fresh water first, reducing the amount of chlorinated water absorbed. Some swimmers apply a thin layer of coconut oil or swim-specific protective oil to the skin to create a slight physical barrier.

2. Always wear goggles: Whether training or swimming recreationally, goggles should be worn to protect the eyes. Choose well-sealed anti-fog goggles and rinse them with fresh water after swimming.

3. Shower immediately after swimming: Use fresh water (or a mild, soap-free body wash) to thoroughly cleanse the skin and hair, removing residual chloramines. The longer you delay showering, the longer the chlorine contact time.

4. Moisturize after swimming: Apply moisturizing lotion immediately after showering (while the skin is still slightly damp to lock in moisture), paying special attention to easily dried areas such as the hands, lower legs, and face.

5. Those with asthma or allergies should choose outdoor pools: Outdoor pools have far better ventilation than indoor ones, resulting in lower trichloramine concentrations and being friendlier to the respiratory system. Under Taiwan’s climatic conditions, outdoor swimming is suitable for most months of the year.

6. Consider swimming in seawater or natural waters: Seawater contains no chlorine and is far less irritating to the skin and respiratory tract than pools. Taiwan’s eastern and southern regions have excellent seawater swimming resources that can serve as a supplementary option to pool training.

Conclusion

Chlorinated water is the guardian of modern pool safety, but the negative effects of long-term exposure on the skin, eyes, respiratory tract, and hair are real. For Taiwanese people who swim frequently, taking precautions beforehand, cleansing and moisturizing afterward, and choosing pools with lower chlorine concentrations or outdoor pools when possible can effectively reduce the cumulative damage from chlorinated water. The health benefits of swimming far outweigh the negative effects of chlorine, but understanding and managing these effects allows swimming to be healthier and more comfortable.

Related Reading

• Swimming and Skin Protection: The Effects of Chlorinated Water on the Skin and Skincare Advice
• Chlorine Allergy: A Complete Guide to Swimming Dermatitis and Eye Protection
• The Effects of Chlorine on the Skin and Eyes: A Complete Post-Swim Care Routine and Product Selection
• Swimming and Skin Conditions: Care Solutions for Chlorine Dermatitis and Dryness