Environmental Impact Assessment - Stage 2

Stage 2: Identify areas where air pollution is a potential threat to ecosystems
01 Develop a plan for assessing potential threats to ecosystems and ecosystem services
02 Identify sources of ambient air pollution and ecosystem data
03 Identify areas where crop yield is at risk from ozone pollution
04 Identify areas where tree growth and carbon sequestration are at risk from air pollution
05 Identify areas where biodiversity is at risk from air pollution
06 Identify areas where lake and river systems are at risk from air pollution
07 Identify areas where aerosol pollution is potentially affecting visibility
08 Translate results into useful information for decision makers
09 Review key categories of ecosystem services relevant to your jurisdiction
10 Make a data improvement plan for Stage 3 assessments

Stage 2: Identify areas where air pollution is a potential threat to ecosystems

Using national and global sources, in Stage 2 you will collate available data on air pollution for your jurisdiction, including for ozone and aerosol concentrations and the deposition of nitrogen and sulfur compounds. By mapping exceedance of critical levels for ozone established by the LRTAP Convention, you will identify areas where provisioning services (crop yield and timber from trees) are at potential risk of damage. Areas where there could be impacts of ozone, S and N deposition on carbon sequestration by trees (a climate regulating service) will also be identified. Exceedances of critical levels (for ground-level O3, and ammonia NH3) and loads (eutrophication and acidification from Nnitrogen and Ssulfur deposition) will be mapped for vulnerable ecosystems, including for on-land and freshwater-based ecosystems. Together with impacts on visibility, these ecosystem impacts will be considered in the context of recreational activities such as fishing and appreciation of nature. An important part of stage 2 is to engage with stakeholders including national policy makers, conservation agencies, charities and the public, to raise awareness of the air pollution problems in your jurisdiction.

Key objectives:

  • Develop a preliminary environmental impact assessment to assess the potential sensitivity of dominant ecosystems in your jurisdiction and the services they provide.
  • Consider multiple air pollutants (e.g. ozone, aerosols) and types of air pollution impact (e.g. acidification, eutrophication).
  • Raise awareness of the air pollution problems in your jurisdiction by engaging with stakeholders including national policy makers, conservation agencies, charities and the public. 

01 Develop a plan for assessing potential threats to ecosystems and ecosystem services

To effectively assess the dominant ecosystems and ecosystem services within your jurisdiction, it is essential to evaluate the specific threats posed by factors such as acidification, eutrophication, ozone pollution, and visibility degradation. Begin by reviewing the physical geography of the area, as well as relevant scientific literature that documents air pollution-related damage to various habitats, including agricultural lands, forests, aquatic ecosystems, and biodiversity hotspots. This comprehensive analysis will help you identify potential threats from air pollution and quantify the ecosystem service (and natural capital) benefits that could arise from effective air pollution reduction. By understanding the interconnections between air quality and ecosystem health, you can better prioritize actions to protect and enhance the environmental integrity of the region, ultimately contributing to sustainable management and conservation efforts and further justifying air quality protection programs. 

02 Identify sources of ambient air pollution and ecosystem data

To support ecosystem assessment efforts, start by identifying available national and global datasets used to analyze air quality impacts. Focus on gathering data on air pollution concentrations, particularly for ozone and aerosol levels, as well as deposition data related to nitrogen and sulfur compounds. Additionally, incorporate land cover and land use, soil type, and data on agricultural and forestry productivity. 
Connect with the monitoring program (See AQ monitoring guidance Stage 2, Step 1) which highlights the necessity for data collection in rural and remote areas, ensuring comprehensive coverage. While global datasets provide valuable information, prioritize the collection of national-level data for accuracy. Sourcing air pollution concentration and deposition data from validated chemistry transport models is ideal, as this ensures continuous data fields. 
In cases where modeling is not available, leverage site-specific data from air pollution monitoring locations or internationally collated datasets like the TOAR database for informed assessments. Creating overlay maps can help visualize the intersections between pollution and ecosystem health, enabling you to identify ecosystems most threatened by air pollution to prioritize in the subsequent steps of your assessment process. 

03 Identify areas where crop yield is at risk from ozone pollution

Identify input data to estimate exceedance of air quality limits for ozone induced crop yield. This will include arable crop distribution for dominant crop species (spatial distribution and crop growing seasons) and production statistics at national level. Identify and collate ozone concentrations, either from site-specific monitoring or ideally modelled data; identify critical levels from concentration-based response functions for dominant crop types of country from Mills et al (2007) and the LRTAP Convention's Modelling and Mapping Manual, and identify O3 metric (e.g. M7 or AOT40) used by dose-response relationship. At Stage 2 we stop with an estimate of the level of exceedance of standards; however, the impacts associated with this exceedance will be calculated in Stage 3. 

04 Identify areas where tree growth and carbon sequestration are at risk from air pollution

Begin by identifying the input data necessary to estimate the exceedance of air quality limits that protect forests from ozone, acidification, and eutrophication. Gather and collate information on forest distribution, including spatial patterns and tree growth periods for dominant species, such as deciduous, coniferous, and tropical trees. Convert ozone concentrations into the AOT40 metric to facilitate further analysis. Next, determine the critical loads for nitrogen and sulfur deposition, as well as the critical levels for ozone, specific to forest species in your jurisdiction, to support exceedance mapping. These concepts are described in the third reference below. Finally, develop exceedance maps for nitrogen and sulfur deposition alongside forest distribution maps, enabling better visual understanding of areas at risk and guiding appropriate protective measures for forest ecosystems. 

05 Identify areas where biodiversity is at risk from air pollution

To protect biodiversity from the impacts of air pollution, begin by identifying the necessary input data to estimate the exceedance of air quality limits related to ozone, acidification, and eutrophication. Collect and compile data on land cover and land use distribution that is relevant to biodiversity, focusing on habitats crucial for various species. This may include wetlands, forests, grasslands, and aquatic ecosystems, which are particularly vulnerable to pollution and can suffer from the loss of sensitive flora and fauna, such as amphibians, migratory birds, and key pollinators. 
Convert ozone concentrations into the AOT40 metric to facilitate assessment of exposure levels. Additionally, identify the critical load values for nitrogen and sulfur, as well as the critical levels for ozone that impact dominant ecosystems within your jurisdiction. Finally, develop maps illustrating the exceedance of nitrogen and sulfur deposition, along with ozone concentrations, overlaid with biodiversity distribution maps. This will highlight areas at risk, guiding conservation efforts and improving policy responses to safeguard affected ecosystems and their associated biodiversity. 

06 Identify areas where lake and river systems are at risk from air pollution

To assess the aquatic impacts of air pollution, start by collecting tools and input data necessary to evaluate exceedance of air quality limits aimed at protecting aquatic ecosystems from acidification and eutrophication. Gather data on surface water distribution and identify critical loads for nitrogen and sulfur deposition relevant to your jurisdiction. This information is vital for understanding how pollutant levels affect water quality and aquatic life. Finally, develop maps that illustrate areas of exceedance for nitrogen and sulfur deposition overlaid with surface water data to highlight regions most at risk and guide protective measures for aquatic ecosystems. 

07 Identify areas where aerosol pollution is potentially affecting visibility

To assess visibility impacts across a jurisdiction, utilize a combination of monitoring tools, modeling techniques, and empirical data analysis. Begin by deploying or identifying availability of existing visibility monitoring equipment in strategic locations (e.g. airports, national parks or locations that have visibility as an air quality-related value) to collect real-time data on particulate matter, aerosol concentrations or visual range, which are critical for understanding visibility impairment. Use models like the AERMOD or CALPUFF to understand localized source impacts or assessments provided by national agencies (federal airport authorities) to evaluate regional visibility trends. Additionally, gather historical visibility data and meteorological information to identify the sources of impairment and their correlation with pollution levels. Methods used by the US Interagency Monitoring of Protected Visual Environments (IMPROVE) program may be useful to develop systematic methods for evaluating regional visibility trends. Use these data and methods to develop exceedance maps of aerosol pollution that will limit visibility. 

08 Translate results into useful information for decision makers

To effectively communicate the impacts of air pollution exceedances on ecosystems and ecosystem services, several good practice reports, websites and brochures serve as valuable examples of how the information gathered can be used to showcase the threat that air pollution represents for critical ecosystems and habitats. For example, the World Health Organization (WHO) supports One Health that is an integrated, unifying approach that optimizes the health of people, animals and ecosystems. The European Environment Agency (EEA) offers reports on air quality indicators that outline how exceedances can influence soil, water, and vegetation health, detailing critical loads and levels for various ecosystem types. The U.S. EPA's Air Quality & Ecosystems website provides layman-friendly explanations of how air pollution affects wildlife habitats and biodiversity, while also detailing the methods used to assess these impacts.
Partnerships among institutions such as environmental NGOs, governmental agencies, and local communities are crucial in promoting these resources. Collaborative efforts can enhance monitoring guidance for air quality standards for vegetation by establishing clear critical loads and levels. For example, the UNECE Air Convention’s International Cooperative Programme on Modelling and Mapping of Critical Levels and Loads and Air Pollution Effects, Risks and Trends works to develop scientific guidelines and methods to assess potential damage and to inform regulatory frameworks, ensuring that air quality standards are protective of natural ecosystems. Engaging with stakeholders, including academic institutions and environmental organizations, fosters a shared understanding of air pollution impacts, empowering communities to take action based on the findings presented in these informative reports.

09 Review key categories of ecosystem services relevant to your jurisdiction

Based on preliminary exceedance mapping performed in Steps 3-7, revisit your jurisdiction's dominant ecosystems that are threatened by air pollution identified in Step 1. Are revisions needed? Which ecosystems services might be most threatened by air pollution impacts and consider how these might affect human health and wellbeing as well as economic activities. Additional health threats identified can be connected to AQMx health impact assessment guidance (See Health Impact Assessment Guidance, Stage 2 Step 2) and/or in Stage 3 of this Environmental Benefits guidance.  

10 Make a data improvement plan for Stage 3 assessments

Based on your determination of potential for ecosystem sensitivity to air pollution (determined by exceedance mapping), make a plan to prioritize and enhance the data needed for a more detailed formal assessment of ecosystem services impacted by air pollution. How can this data be collected? What additional monitoring is needed? What changes to air quality monitoring programs may be needed to support ecosystem assessments? Do you need to establish formal relationships with agriculture, forestry or hydrometeorological departments?