Donna McGettigan (Clare, Sinn Fein)
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310. To ask the Minister for Communications, Climate Action and Environment if he will request an impact risk assessment on the health impact of autism and Alzheimer’s disease due to increases chemtrail activity over Ireland. [23483/25]

Donna McGettigan (Clare, Sinn Fein)
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309. To ask the Minister for Communications, Climate Action and Environment if the Environmental Protection Agency has carried out a health risk assessment or environmental risk assessment on chemtrails; and if he will make a statement on the matter. [23482/25]

Darragh O'Brien (Dublin Fingal East, Fianna Fail)
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I propose to take Questions Nos. 310 and 309 together.

My Department has not commissioned any research on chemtrails, climate engineering or geoengineering activities within Irish airspace.

Claims regarding chemtrails frequently stem from suspicions regarding the trails that can be seen from passing aircraft. My Department has no evidence to suggest that such trails are anything other than normal condensation trails (contrails) or have any impact on the environment or health.

Vapour trails are formed through the emission of exhaust gases from jet engines of aircraft in the upper troposphere and the main component of these gases is water vapour. Ambient air temperature at jet cruising altitudes is often below -500C. Under these conditions, water vapour cools and condenses and the particles act as ice nuclei, leading to the production of ice crystals; these ice crystals are what are visible from the ground as a linear cloud of condensation.

Depending upon atmospheric conditions, these vapour trails can rapidly dissipate or remain for some time, gradually spreading horizontally into an extensive thin cirrus cloud layer. Water in the atmosphere commonly evaporates to become water vapour. As a general rule, the drier the air the more effective this evaporation process will be. Under more humid conditions, there will be less effective evaporation and so contrails will generally last longer in more humid air. Contrail formation is also influenced by wind speeds, with higher winds disrupting and breaking up contrail formation.

Contrails do not adversely impact ambient air quality in Ireland. The Environment Protection Agency publishes a comprehensive annual report on air quality. The most recent report Air Quality in Ireland 2023 www.epa.ie/publications/monitoring--assessment/air/air-quality-in-ireland-2023.php was published in September 2024 outlining key indicators of Ambient Air Quality and may be of interest to the Deputy.