The potential of urban environmental control in alleviating heat-wave health effects in five US regions

Heat waves can cause severe thermal environmental stress leading to higher hospital admission rates, health complications, and increased mortality. These effects arise because of one or more meteorology-related factors such as higher effective temperatures, both during the day and at night which inhibits cooling of buildings, increased solar load on buildings causing higher indoor temperatures, increased number of consecutive hot days, stagnation, increased humidity, increased pollutant emissions, and accelerated photochemical smog and particulate matter formation.

Certain urban-climate and environmental control strategies could be implemented to help reduce the negative impacts of heat waves in the U.S. Short-term urban environmental controls, for example, include modifications to urban surface albedo, reforestation, and a reduction in anthropogenic heat flux. Long-term strategies include smart growth, land-use planning, land-cover control, urban design/geometry, passive solar systems, and transport-related actions.

This study, currently in its initial stages, will examine the potential of short-term control strategies in reducing the above-mentioned impacts of heat waves. The study will rely on mesoscale meteorological modeling and heat/health impact assessment in five U.S. regions (CA, NY, MD, IL, and TX). Earlier results for the Los Angeles Basin indicate that these strategies could modify meteorological conditions, e.g., an urban area-averaged temperature reduction of up to 2ºC (with corresponding average decrease of 0.2ºC in dew point temperature and changes of up to 1.5 m/s in wind speed) and, as a result, reduce heat-related impacts significantly. By analyzing several heat waves that have occurred within the past decade in the Los Angeles area, it is estimated that these changes in meteorological conditions could have reduced heat-related mortality by up to 25%. This paper will present initial results from other regions as well.