Background and Motivation

In late 2024, peaceful demonstrations in Tbilisi, Georgia were met with extensive use of chemical crowd-control agents, predominantly tear gas projectiles containing high-dose CS (ortho-chlorobenzylidene malononitrile). These devices were deployed repeatedly in dense urban environments, including areas adjacent to schools and residential buildings.

Despite the classification of tear gas as a “less-lethal” tool, contemporary scientific literature provides limited evidence on the real-world physiological impact of large-scale deployments. Most existing data comes from controlled exposures in healthy volunteers or from military training settings, which do not reflect the environmental conditions, population diversity, or exposure concentrations seen during mass protests.

Our goal was to examine whether individuals exposed to tear gas under these real-world conditions exhibited measurable cardiovascular, microvascular, or respiratory effects, and to characterize the symptom patterns surrounding both acute and persistent manifestations.

Study Overview

The study was conducted from January 9 to March 1, 2025, following the November–December protests. Data collection included:

• 347 structured survey responses

• 69 full clinical evaluations assessing:

  • 12-lead electrocardiography (ECG)

  • Nailfold capillaroscopy

  • Complete blood count (CBC) and coagulogram

  • Blood pressure and oxygen saturation

• 31 unexposed controls, matched for key demographic variables

This design enabled the assessment of both subjective symptom burden and objective physiological findings.

Key Findings

Electrocardiographic abnormalities

Participants exposed to tear gas demonstrated a significantly higher prevalence of:

• Right bundle branch block (RBBB)

• T-wave inversions

• More frequent P-wave and QRS-complex abnormalities

These findings may reflect pulmonary microvascular stress, altered right ventricular loading, or transient myocardial hypoxia following chemical inhalation.

Capillaroscopic findings

Although not statistically different between groups, exposed individuals exhibited a higher proportion of:

• Non-specific capillary abnormalities

• Several cases with sclerodermal-pattern microangiopathy

These patterns warrant further investigation regarding potential endothelial effects of CS exposure.

Respiratory involvement

We identified two clinically significant respiratory cases:

• Hypersensitivity pneumonitis

• Persistent pneumonia with obstructive impairment

Both cases emerged within days of exposure and were confirmed through imaging and pulmonary function testing.

Symptom dynamics

Symptoms such as headache, cough, fatigue, ocular irritation, and skin discomfort were highly prevalent during exposure. Importantly, many persisted 30 or more days after the incident.

Noteworthy associations included:

• Allergy status as a strong predictor of total symptom burden

• No protective effect for any mask type

• No correlation between frequency of attendance and severity, suggesting that even single high-intensity exposures can produce measurable effects

Laboratory parameters

CBC and coagulogram findings remained largely within reference ranges.

Public Health and Policy Considerations

Our findings highlight the need to reconsider assumptions around the safety profile of CS tear gas, particularly in civilian contexts. The observed ECG changes, documented respiratory cases, and persistent symptomatology suggest that:

• Current regulatory frameworks may underestimate the physiological risks of tear gas.

• Deployment in densely populated areas—especially near children—presents substantial public health concerns.

• There is a need for independent oversight, stricter operational guidelines, and longitudinal follow-up for exposed populations.

This work contributes to a broader conversation on the health, legal, and ethical implications of chemical crowd-control agents in democratic societies.

Acknowledgments

This research was made possible through the support of Giorgi Kamkamidze and LLC Neolab, who provided essential resources that enabled clinical testing. We also acknowledge Salome Kvaratskhelia for providing verified on-the-ground documentation incorporated into the supplemental materials. Their contributions significantly strengthened the study’s depth and rigor.