Air ions and respiratory function outcomes: a comprehensive review.

Area of Science:

• Environmental Health
• Pulmonary Medicine
• Air Quality Research

Background:

• The purported effects of air ions on human health, particularly respiratory function, have been debated for decades.
• Despite a substantial body of literature, the mechanistic basis for air ions influencing respiratory health remains unclear.
• Claims persist regarding both beneficial and detrimental effects of air ion exposure on the respiratory system.

Purpose of the Study:

• To systematically review and evaluate the scientific evidence from human experimental studies on air ion exposure and respiratory outcomes.
• The review focuses on assessing the impact on respiratory performance and symptoms.

Main Methods:

• A comprehensive literature search identified 23 human experimental studies published between 1933 and 1993.
• Data extraction included study design, participant characteristics, experimental methods, and reported outcomes.
• Random effects meta-analysis was employed where appropriate to synthesize findings.

Main Results:

• Studies investigated the effects of negative air ions on respiratory outcomes like ventilatory function and asthma symptoms.
• Participant groups varied widely, including infants with asthma and adults with emphysema.
• Outcome measures encompassed subjective symptoms, sensitivity, and clinical pulmonary function, with considerable heterogeneity across studies.

Conclusions:

• The existing literature does not provide clear support for negative air ions improving respiratory function or alleviating asthma symptoms.
• Human experimental studies collectively do not indicate significant adverse effects from positive air ion exposure on respiratory measures.
• Overall, air ion exposure (both negative and positive) does not appear to play a significant role in respiratory function.