Temporal Association Between Nonfatal Self-Directed Violence and Tree and Grass Pollen Counts

Area of Science:

• Environmental Health
• Epidemiology
• Psychiatry

Background:

• Previous research indicates a potential link between pollen exposure and suicide.
• No studies have investigated the relationship between pollen and attempted suicide.

Purpose of the Study:

• To examine the temporal association between airborne pollen counts and nonfatal suicidal and nonsuicidal self-directed violence (SDV).
• To investigate seasonal variations in pollen levels as a potential factor influencing suicidal behavior.

Main Methods:

• Utilized daily emergency department visit data for nonfatal SDV (ICD-9 criteria) from Parkland Memorial Hospital (2000-2003).
• Collected concurrent daily airborne tree, grass, and ragweed pollen data for Dallas from the National Allergy Bureau.
• Employed time series analysis using generalized autoregressive conditional heteroskedasticity (GARCH).

Main Results:

• A statistically significant positive temporal association was found between tree pollen counts and nonfatal SDV events in women (P = .04).
• Significant positive temporal associations were observed between grass pollen counts and nonfatal SDV events in both men (P = .03) and women (P < .0001).
• No significant temporal association was detected between ragweed pollen counts and nonfatal SDV events.

Conclusions:

• Findings suggest that increased nonfatal SDV is associated with elevated tree and grass pollen counts.
• This study provides the first evidence linking seasonal variations in tree and grass pollen to nonfatal SDV.
• Pollen count may be a contributing factor to seasonal patterns in suicidal behavior.