Last month, we发言语蒸汽侵入的可能性以及蒸汽侵入的调查和减轻;有机蒸汽的可能性，进入居民，商业或工业空间，具有不良人体健康影响。通过控制室内空间内部或下方的环境条件来修复这些有机蒸汽的来源或减轻曝光潜力可以是工程挑战。
The factors that go into the best solution include, but are not limited to:
- 新与现有建筑
- 污染物的实际来源和质量
- 一个人试图影响的媒体（例如，土壤，地下水，土壤蒸汽）
- 正在解决的结构的大小
- 年龄
- 建筑建筑材料
- 设计和建筑HVAC控制
Once the potential for vapor intrusion is established through proper engineering and scientific investigation (as influenced by requirements or guidance where they exist), one must assemble the information on the structure, or portion of the structure to be mitigated, and then design and value-engineer a solution that meets several potentially competing objectives.
我们的顾问一直在执行这项工作超过25年，虽然许多州在过去十年之前没有出版指导，但如果有的话。我们的作品从大型工业制造设施，商业建筑，办公大楼，带式商场，小型一层办公楼，到多家和单户主的家庭。蒸气侵入的潜力和现实不仅与旧工业设施相关联。
Mitigation of actual or perceived vapor intrusion (it is not easy to absolutely know that vapors are entering a structure) is not the same as remediation of the source of those vapors. Sometimes it is acceptable, from a regulatory standpoint, to leave the source where it is. This may seem contradictory to environmental laws but is consistent with risk-based site cleanups which are acceptable at the federal and most state levels. Remediation will remove or destroy the source contaminants, where mitigation simply controls the exposure pathway. In the case of vapor intrusion, the main mitigation objective is to keep the vapors from entering an occupied space where inhalation exposure can lead to human health consequences.
If one can reasonably remediate the source of the vapors, or if you are a responsible party and required to do so, then remediation and mitigation may be the same. Although still costly, mitigation is usually less expensive and time-consuming than remediating the source of vapors. Typical capital or up-front costs for vapor mitigation systems can range from $2.00 to $6.00/ft2of the ground level square footage of the structure. You may be required to have an environmental covenant or property deed restrictions on the property and may have to perform on-going monitoring and reporting.
As we briefly discussed last month, there are well-proven ways to mitigate vapor intrusion. While at first glance it may seem as simple as modifying a building’s HVAC system so that the building is always “pressurized” (and therefore, does not allow the vapors to enter into the building through maintenance of a pressure gradient), this method will likely prove to be impractical and costly.
Sealing a building’s floors, walls, sumps, utility corridors, or other direct pathways from underlying soils into a building also seems like an inexpensive mitigation step but can be hard to accomplish. It is comparable to sealing against water intrusion in basements constructed in saturated soils – a losing battle against Mother Nature.
So,depressurization或者通风the “sub-slab” space beneath a building are the predominant choices for vapor mitigation of structures of all kinds. Typical sub-slab depressurization systems (SSDS) are very much like radon systems that you may have in your home. Sub-slab venting systems (SSVS) are a bit different from SSDS in that they typically include the introduction of fresh air into the sub-slab space which can lead to lower energy costs to provide mitigation protection.
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