Context

To enable human mobility, economic vitality, and population well-being in growing cities, well-planned transportation infrastructure is essential. However, transportation systems can also have detrimental impacts on health and equity, including through increased air pollution and its unequal social distribution.

Aims

This study focuses on estimating air quality and equity impacts of an ongoing large-scale metropolitan transportation program (known as “Tampa Bay Next”). Our objective was to characterize and quantify the air pollution levels and population exposures resulting from an interstate freeway expansion planned under Tampa Bay Next, which includes added toll lanes.

Methods

We estimated changes in individual human exposures to oxides of nitrogen (NO_x) due to the proposed freeway changes, using an integrated suite of high-resolution models for travel demand, emissions, pollutant dispersion, and exposure. Inequity in the distribution of exposures among racioethnic and income groups was also estimated using a few measures of inequality (the subgroup inequality index (SII), the comparative environmental risk index, and the toxic demographic quotient index).

Findings

The planned freeway expansion was estimated to slightly decrease the daily NO_x emissions (by 5.6 mg/m, p = 4×10⁻¹⁶), ambient concentrations (by 0.02 μg/m³, p = 2×10⁻⁴), and individual exposures (by 0.2 μg/m³, p = 2.2×10⁻¹⁶) on average, while increasing exposure densities during peak periods in areas surrounding downtown Tampa. Group-average exposures also decreased for all population subgroups under the planned expansion scenario. However, disparities in exposure increased for the black (ΔSII = 1.3×10⁻³ for the 90th percentile exposure level) and the below-poverty (ΔSII = 4.6×10⁻³) groups.

Conclusions

Results suggest that a detailed analysis of exposures may be needed to ensure large-scale transportation improvement programs reduce inequity, even when average impacts on air quality and exposures are positive or neutral.

中文翻译：

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大都市规模的高速公路扩建计划对空气污染和公平的影响

语境

为了在不断发展的城市中实现人口流动、经济活力和人口福祉，精心规划的交通基础设施至关重要。然而，交通系统也可能对健康和公平产生不利影响，包括空气污染加剧及其社会分布不均。

宗旨

本研究侧重于评估正在进行的大型城市交通计划（称为“下一个坦帕湾”）对空气质量和公平性的影响。我们的目标是表征和量化由坦帕湾下一步计划中的州际高速公路扩建所导致的空气污染水平和人口暴露，其中包括增加的收费车道。

方法

我们使用一套集成的高分辨率模型来评估出行需求、排放、污染物扩散和暴露，估计由于拟议的高速公路变化而导致的个人氮氧化物 (NO _x ) 暴露量的变化。还使用一些不平等的衡量标准（亚组不平等指数 (SII)、比较环境风险指数和有毒人口商数指数）估计了种族和收入群体之间暴露分布的不平等。

发现

据估计，计划中的高速公路扩建将略微降低每日 NO _x排放量（5.6 mg/m，p  = 4×10 ^-16）、环境浓度（0.02 μg/m ³，p  = 2×10 ^-4）和平均个人暴露（0.2 μg/m ³，p  = 2.2×10 ^-16），同时在坦帕市中心周围地区的高峰期增加暴露密度。在计划的扩张情景下，所有人口亚组的组平均暴露量也有所下降。然而，黑人（第 90 个百分点的暴露水平的ΔSII = 1.3×10 ^-3）和贫困以下人群（ΔSII = 4.6×10⁻³ ) 组。

结论

结果表明，即使对空气质量和暴露的平均影响是积极的或中性的，也可能需要对暴露进行详细分析，以确保大规模的交通改善计划减少不公平。