The impact of urban heat islands on health
Urban heat islands (UHIs) are caused by various factors, including the absorption of solar radiation by buildings and pavements, reduced ventilation, scarcity of greenery, and residual heat from vehicles and industrial processes. The increased heat in cities, affects a wide range of physical and mental health outcomes for urban populations.
According to a study conducted in the United States, a 10°F increase in daily temperature is associated with a 4.3% increase in same-day emergency hospitalizations for respiratory diseases, highlighting the direct and acute health risks posed by elevated urban temperatures. In Europe, UHI-induced heat-related mortality has significant health and economic implications, with healthcare costs estimated at approximately €200 per urban inhabitant per year.
More frequent and intense heat waves triggered by climate change are especially dangerous when combined with the UHI effect. During heat waves, the temperature difference between urban and rural areas can be even more pronounced, leading to higher mortality rates. High urban temperatures exacerbate conditions such as heat exhaustion and heat stroke, disproportionately affecting vulnerable populations like the poor, the elderly, children, and individuals with pre-existing health conditions. People who have less access to air conditioning and green spaces, and are more exposed to other environmental stressors such as air pollution and noise, may have compounding health conditions related to their urban environment.
Lung
The most severe health impacts of UHIs are respiratory, cardiovascular, and mental. UHIs significantly impact respiratory health, and the combination of high temperatures and air pollution can create a harmful environment for individuals with respiratory issues. Higher temperatures can lead to an increase in ground-level ozone, a major component of smog, which can irritate the respiratory system, trigger asthma attacks, and worsen chronic respiratory conditions such as chronic obstructive pulmonary disease (COPD).
Heart
Heat stress can increase the risk of heart attacks, strokes, and other cardiovascular events. Dehydration, which is more likely in hot conditions, can lead to an imbalance of electrolytes and blood pressure fluctuations, further straining the heart. Studies have shown that during periods of extreme heat, there is a marked increase in mortality and morbidity related to cardiovascular diseases.
Mind
Mental health can also suffer due to the stress and discomfort caused by prolonged exposure to high temperatures. Increased heat can lead to sleep disturbances, irritability, and cognitive impairments. For individuals with mental health conditions, these effects can be more pronounced, exacerbating symptoms and reducing overall well-being. The discomfort and stress associated with living in hot environments can increase aggressive behavior and reduce social cohesion, negatively impacting community health and safety.
With so many different facts of urban living that contribute to UHI effect, a multifaceted approach to decreasing temperatures is essential. Many cities are committed to increasing green space to address these issues. To make a difference for building interiors, however, passive cooling strategies are effective and do not further contribute heat to the environment the way that traditional air conditioning does. Pirta’s passive cooling paint in particular can be easily and effectively applied to existing infrastructure. This affordable, non-toxic, water-based, and VOC-free paint formulation provides strong solar reflectivity and thermal emittance. By reflecting the sun's energy and releasing heat away from a surface, Pirta paint can significantly reduce both indoor and outdoor temperatures, thereby mitigating the health risks associated with UHIs.
The health impacts of urban heat islands are extensive and affect vulnerable populations disproportionately, and the need for equitable and effective interventions is urgent. Passive cooling technologies like those developed by Pirta offer a promising solution, helping to create cooler, healthier, and more livable urban environments. By incorporating such innovations into urban planning and building design, cities can better protect their populations and improve public health outcomes in the face of rising temperatures and increasing urbanization.
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