Abstract Cities in drylands are expected to experience increasing challenges when it comes to air pollution. Currently, concentrations of particulate matter in these cities frequently reach dangerous levels. Urban afforestation represents an alternative to increase human health in arid cities via air-filtering and dry deposition. By simulating a non-existing market through a contingent valuation protocol, this study estimates the willingness to contribute monetarily to an urban afforestation scenario in Mexicali –an arid city located at the US-Mexico border. We estimate an average annual willingness to pay (WTP) of (2019) USD 88 per household. Variations in WTP are associated with the respondent’s perception of air quality and the presence of respiratory symptoms in the respondent’s household. The smallest WTP (USD 75) is reported by those perceiving poor air quality in their neighborhood and with no household members affected by respiratory symptoms. Respondents perceiving good air quality and with at least one household member facing respiratory symptoms report a WTP of USD 99. The highest WTP represents around 0.8% of the annual household income. This WTP, when extrapolated to and aggregated over the total number of households in Mexicali, justifies the implementation of an urban afforestation program supplying 30 thousand tree seedlings annually.

中文翻译：

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通过在干旱城市进行城市植树造林改善空气质量所带来的好处——墨西哥下加利福尼亚州墨西卡利的或有估值

摘要 在空气污染方面，旱地城市预计将面临越来越多的挑战。目前，这些城市的颗粒物浓度经常达到危险水平。城市植树造林是通过空气过滤和干沉降来提高干旱城市人类健康的一种替代方法。通过使用条件估值协议模拟一个不存在的市场，本研究估计了为墨西卡利（位于美墨边境的干旱城市）的城市植树造林情景做出金钱贡献的意愿。我们估计每个家庭的平均年支付意愿（WTP）为（2019 年）88 美元。WTP 的变化与受访者对空气质量的感知以及受访者家庭中呼吸道症状的存在有关。认为附近空气质量差且没有家庭成员受到呼吸道症状影响的人报告的支付意愿最小（75 美元）。认为空气质量良好且至少有一名家庭成员面临呼吸道症状的受访者报告的支付意愿为 99 美元。最高支付意愿约占家庭年收入的 0.8%。该 WTP 外推并汇总到墨西卡利的家庭总数后，证明了实施每年提供 3 万株树苗的城市造林计划是合理的。家庭年收入的 8%。该 WTP 外推并汇总到墨西卡利的家庭总数后，证明了实施每年提供 3 万株树苗的城市造林计划是合理的。家庭年收入的 8%。该 WTP 外推并汇总到墨西卡利的家庭总数后，证明了实施每年提供 3 万株树苗的城市造林计划是合理的。