What Is an ESG Dive?

Introduction to ESG Dive

An ESG dive is an in-depth, granular investigation into a company's or fund's Environmental, Social, and Governance (ESG) practices that goes well beyond a surface-level rating or a quick label check. Rather than relying on a single letter grade or a simple pass/fail screen, an ESG dive requires analysts to pull apart disclosures, operational data, supply chain practices, board structures, and compliance records to understand the real sustainability-linked risks and opportunities embedded in an investment.

This term has become increasingly important as capital markets place greater weight on sustainability factors. Global ESG-labeled assets under management surpassed $30 trillion in 2022, according to the Global Sustainable Investment Alliance's Global Sustainable Investment Review, underscoring how mainstream ESG considerations have become for institutional allocators, pension funds, hedge funds, and private wealth managers alike. With that scale of capital flowing into sustainability-linked strategies, investors need rigorous tools to separate genuine ESG leadership from superficial marketing claims.

This article will define what an ESG dive entails, explain the methodologies and step-by-step processes analysts use to conduct one, review the major frameworks and data providers that inform the analysis, and explore how hedge funds and alternative investment vehicles apply ESG dives in real-world due diligence and portfolio construction.

What Does 'ESG Dive' Mean? Defining the Term

To understand an ESG dive, it helps to break the phrase into its two component parts: the "ESG" framework itself, and the "dive" methodology applied to it. Together, they describe a rigorous, multi-layered research process rather than a single data point or label.

ESG as a Framework for Non-Financial Risk Assessment

ESG stands for Environmental, Social, and Governance—three categories of non-financial risk and opportunity that can materially affect a company's long-term performance, even though they rarely appear on a traditional income statement or balance sheet. Environmental factors cover issues like carbon emissions, resource consumption, and exposure to climate transition risk. Social factors address how a company treats its workforce, suppliers, and surrounding communities. Governance factors examine board structure, executive incentives, and the integrity of corporate decision-making. Collectively, these three pillars give investors a lens into risks that conventional financial statements often fail to capture, such as reputational damage from a labor scandal or regulatory penalties tied to environmental non-compliance.

"Dive" as a Deep, Granular Analytical Process

The word "dive" signals that the analysis goes far deeper than a passive glance at a published score. A genuine ESG dive involves pulling primary source disclosures, cross-referencing third-party data, interviewing management where possible, and stress-testing assumptions against industry-specific benchmarks. It is an investigative exercise, not a checkbox exercise—closer in rigor to traditional fundamental equity research than to a compliance review.

ESG Dive vs. a Simple Score Lookup

This distinction matters because many investors mistakenly equate "doing ESG research" with simply checking a rating. Consider the MSCI ESG Ratings scale, which ranks companies from AAA (leader) down to CCC (laggard). While this scale offers a useful starting snapshot, it compresses hundreds of underlying data points into a single letter grade. An ESG dive uses that rating as a jumping-off point rather than an endpoint, digging into the underlying methodology, data gaps, and sector-specific weightings that produced the score in the first place. Analysts conducting a true dive often find that two companies with identical letter grades carry very different risk profiles once the underlying data is unpacked.

Applicable Across Companies, Funds, and Portfolios

An ESG dive is not limited to single-stock analysis. It can be applied to an individual company ahead of an equity investment, to an entire fund as part of limited partner due diligence, or across a full multi-asset portfolio to assess aggregate exposure to sustainability-linked risks. This flexibility makes the ESG dive a foundational tool across the institutional investing ecosystem, from long/short equity desks to private equity allocators evaluating fund-of-funds structures.

Why Investors and Analysts Conduct an ESG Dive

The motivations behind an ESG dive extend well beyond reputational box-checking. For institutional investors, analysts, and allocators, a deep ESG review has become a practical risk management and value-creation discipline, driven by a convergence of regulatory, market, and fiduciary pressures.

Risk mitigation is often the primary driver. Surface-level screening can miss hidden environmental liabilities—such as unremediated contamination sites, undisclosed carbon-intensive supply chains, or pending litigation tied to pollution events. Similarly, labor controversies, from supply chain forced-labor allegations to workplace safety violations, frequently surface only after an activist investor or journalist digs into operational detail that standard ratings never capture. Governance red flags, including related-party transactions, weak board independence, or executive compensation misaligned with long-term performance, can signal deeper structural problems that precede financial deterioration. An ESG dive is designed to surface these issues before they manifest as price shocks or reputational crises.

Regulatory pressure has intensified the need for rigorous diligence. In the United States, the SEC's 2024 climate-related disclosure rule now requires many public companies to report greenhouse gas emissions and climate-related financial risks, pushing analysts to validate and contextualize this newly mandated data rather than take it at face value. In Europe, the Sustainable Finance Disclosure Regulation (SFDR) classifies funds into Article 6, 8, and 9 categories based on their sustainability ambitions, compelling fund managers to substantiate claims with granular, defensible evidence—precisely the kind of evidence an ESG dive produces.

Investor demand for authenticity has grown alongside heightened scrutiny of greenwashing. High-profile enforcement actions and media exposés have made allocators wary of funds that market sustainability credentials without substantive underlying practices. An ESG dive provides the forensic detail needed to distinguish genuine sustainability leaders from marketing-driven claims.

Alpha generation is an increasingly cited rationale as well. Analysts use ESG insights to identify companies positioned for long-term value creation—through resource efficiency, regulatory foresight, or stronger stakeholder relationships—as well as those exposed to value destruction from stranded assets or governance failures.

Finally, fiduciary duty obligates institutional allocators, including pension funds and endowments, to conduct defensible due diligence before committing capital. Limited partners increasingly require detailed ESG reporting from fund managers, making the ESG dive a necessary input for satisfying both hedge fund investor reporting requirements and broader institutional governance standards.

The Core Components of an ESG Dive: Environmental, Social, and Governance

An ESG dive systematically examines three interrelated pillars, each capturing a distinct dimension of non-financial risk and opportunity. While the acronym implies equal weighting, in practice analysts calibrate the depth and emphasis of each pillar based on sector dynamics, business model, and asset class.

Environmental Factors

The environmental pillar evaluates a company's physical footprint and exposure to ecological risk. Analysts examine carbon emissions across Scope 1, 2, and increasingly Scope 3 categories, alongside resource consumption metrics such as water usage, energy intensity, and raw material sourcing. Waste management practices—including hazardous waste disposal, recycling rates, and circular economy initiatives—reveal operational efficiency and regulatory compliance posture. Climate risk exposure receives particular scrutiny, encompassing both physical risks (flooding, extreme weather, supply chain disruption) and transition risks (carbon pricing, stranded assets, shifting consumer demand away from fossil fuels). For capital-intensive industries, these factors often determine long-term asset viability.

Social Factors

The social pillar assesses how a company manages relationships with employees, suppliers, and communities. Labor practices under review include wage equity, workplace safety records, unionization policies, and employee turnover rates. Diversity and inclusion metrics—board and workforce representation, pay gap analysis, and inclusive hiring practices—have become standard diligence items as investors link demographic diversity to decision-making quality and talent retention. Supply chain ethics extend scrutiny beyond direct operations to third-party vendors, probing for forced labor risk, conflict minerals sourcing, and fair trade compliance. Community impact measures, such as local economic contribution and stakeholder engagement, round out this pillar, particularly for extractive and infrastructure-heavy industries.

Governance Factors

Governance examines the structural integrity of corporate decision-making. Board composition analysis covers independence, expertise diversity, and tenure to assess whether oversight mechanisms function effectively. Executive compensation structures are reviewed for alignment between pay and long-term performance, rather than short-term stock price movements. Shareholder rights—including dual-class share structures, proxy access, and takeover defenses—indicate how much influence minority investors retain. Anti-corruption policies, whistleblower protections, and audit committee independence further signal management's commitment to ethical operation and legal compliance.

Sector-Specific Weighting

Because materiality varies dramatically by industry, experienced analysts avoid applying uniform weights across all three pillars. In the energy sector, ESG dives frequently allocate 40–50% of analytical weight to Environmental factors, reflecting the outsized importance of emissions intensity, reserve exposure, and transition risk. Conversely, financial services firms—which carry minimal direct environmental footprint but significant systemic risk—tend to weight Governance more heavily, often prioritizing board oversight, risk management frameworks, and regulatory compliance above environmental metrics. Technology companies frequently emphasize Social factors, given their labor-intensive talent models and data privacy obligations. This sector-calibrated approach, often guided by frameworks like the SASB Materiality Map, ensures that an ESG dive produces actionable, industry-relevant insight rather than a generic checklist score.

Step-by-Step: How an ESG Dive Is Conducted

While the scope and formality of an ESG dive can vary depending on whether the subject is a public equity, a private fund, or a fixed-income issuer, the underlying process tends to follow a consistent analytical sequence. Understanding these steps helps investors evaluate whether a given ESG dive was conducted rigorously or merely rubber-stamped using off-the-shelf scores.

Step 1: Data Collection

The process begins with systematic data gathering from multiple sources. Analysts pull company-disclosed materials such as sustainability reports, proxy statements, and 10-K risk disclosures, then supplement this with third-party databases, regulatory filings, litigation records, and NGO or watchdog reports that may surface issues a company has not voluntarily disclosed. This triangulation is critical, since self-reported data alone often presents an incomplete or overly favorable picture.

Step 2: Materiality Assessment

Not every ESG issue matters equally for every company. The second step narrows the analytical focus to the factors most likely to affect financial performance within a given industry. Analysts frequently rely on the SASB Materiality Map, which catalogs industry-specific ESG factors most likely to be financially material—for example, data security for software firms versus water management for agricultural producers. This step prevents the dive from devolving into an unfocused checklist exercise and instead concentrates resources on issues with genuine investment relevance.

Step 3: Quantitative Scoring and Benchmarking

With material issues identified, analysts assign quantitative scores to measurable metrics—emissions intensity, employee turnover, board independence percentages, and similar indicators. These scores are then benchmarked against industry peers and historical trends to determine whether a company is an outlier, laggard, or leader relative to its competitive set. Benchmarking transforms raw data into comparative insight, since an isolated metric carries little meaning without sector context.

Step 4: Qualitative Review

Numbers alone rarely tell the full story. The fourth step incorporates qualitative judgment through management interviews, site visits, and on-site audits where feasible—particularly common in private equity and direct lending contexts where analysts have greater access. These interactions help assess intangible factors such as management's genuine commitment to stated ESG goals, the robustness of internal controls, and whether disclosed policies are actually operationalized rather than existing only on paper.

Step 5: Synthesis and Recommendation

Finally, findings from the quantitative and qualitative stages are synthesized into a cohesive output—typically an investment recommendation, a risk flag report, or an internal memo informing portfolio construction decisions. This synthesis stage requires analysts to weigh conflicting signals, such as strong environmental performance paired with governance red flags, into a single actionable conclusion for portfolio managers or allocators.

Together, these five steps distinguish a genuine ESG dive from a superficial scoring exercise, providing the depth of insight institutional investors increasingly require, particularly as strategies informed by frameworks explored in hedge fund strategies explained incorporate ESG considerations into core investment theses.

Key ESG Frameworks and Data Sources Used in an ESG Dive

A rigorous ESG dive rarely relies on a single information source. Instead, analysts triangulate across standard-setting frameworks that define what to measure and commercial data providers that supply how companies actually score against those measures. Understanding the distinct role each plays is essential to interpreting the outputs of any ESG dive correctly.

SASB: Industry-Specific Materiality

The Sustainability Accounting Standards Board (SASB), now consolidated under the IFRS Foundation, provides industry-specific standards identifying which ESG topics are financially material for 77 distinct industries. Rather than treating all companies under a one-size-fits-all rubric, SASB standards recognize that water usage is material for a beverage manufacturer but largely irrelevant for a software firm. This framework underpins the materiality assessment stage of most ESG dives.

GRI: Broad Sustainability Disclosure

The Global Reporting Initiative (GRI) takes a broader stakeholder-oriented approach, emphasizing comprehensive disclosure of a company's economic, environmental, and social impacts regardless of immediate financial materiality. GRI is widely used for corporate sustainability reporting globally and often serves as the raw disclosure layer that ESG data providers and analysts draw upon during data collection.

TCFD: Climate Risk Reporting

The Task Force on Climate-related Financial Disclosures (TCFD) framework structures climate risk reporting around governance, strategy, risk management, and metrics/targets. TCFD-aligned disclosures have become a near-standard expectation for large-cap issuers and are now embedded into regulatory regimes such as the SEC's climate rule and the EU's Corporate Sustainability Reporting Directive.

Commercial Data Providers

Beyond standard-setters, analysts rely on commercial ESG research platforms to operationalize data collection at scale. Bloomberg ESG Data covers over 11,800 companies globally, integrating sustainability metrics directly into the Bloomberg Terminal workflow analysts already use for financial analysis. Sustainalytics rates more than 16,000 companies worldwide, offering its widely cited ESG Risk Rating methodology. MSCI ESG Research covers roughly 8,500 companies and more than 680,000 equity and fixed income securities, producing the AAA-to-CCC letter ratings referenced earlier in this article. Refinitiv (now part of LSEG) rounds out the major providers with extensive historical ESG datasets favored for quantitative screening and academic research.

No single source is sufficient on its own. A thorough ESG dive, consistent with the strategies employed by sophisticated managers detailed in resources like hedge fund strategies explained, typically cross-references multiple frameworks and providers to compensate for gaps, inconsistent methodologies, and divergent scoring philosophies among commercial raters.

Who Performs ESG Dives? Roles Across the Investment Industry

The responsibility for conducting an ESG dive rarely rests with a single individual or department. Instead, it is distributed across a network of specialists inside and outside the investment organization, each bringing a distinct lens to the analysis.

At large asset managers, dedicated ESG research analysts and sustainability teams sit alongside traditional equity and credit analysts, building proprietary scoring models that overlay or challenge commercial ratings. These teams often report directly to the Chief Investment Officer or a dedicated Head of Sustainability, reflecting the strategic weight firms now place on non-financial risk. Their work typically involves reconciling internal findings with external data providers, flagging material discrepancies, and briefing portfolio managers ahead of allocation decisions.

Hedge fund managers have increasingly folded ESG dives into their core fundamental research process rather than treating sustainability as a separate silo. A long/short equity analyst, for example, may incorporate governance red flags—such as weak board independence or related-party transactions—directly into a short thesis. The number of hedge funds launching dedicated ESG or sustainability research desks has grown steadily since 2020, as managers respond to both performance considerations and investor demand. Professionals pursuing this specialization often follow career paths outlined in resources like how to become a hedge fund manager, which increasingly emphasizes sustainability fluency as a differentiating skill alongside traditional financial training detailed in what is a hedge fund.

Third-party ESG rating agencies and independent consultants serve a complementary verification role. Firms hire these outside specialists to conduct arm's-length assessments, particularly when internal teams lack bandwidth or when investors demand unbiased validation free from potential conflicts of interest tied to in-house research.

Finally, limited partners (LPs) and institutional allocators—including pension funds, endowments, and sovereign wealth funds—conduct their own ESG due diligence before committing capital to external managers. This typically involves questionnaires, on-site visits, and review of a manager's ESG policy documentation, ensuring alignment with the LP's own fiduciary mandates and reporting obligations to their underlying stakeholders. Collectively, these overlapping roles create a system of checks that strengthens the rigor and credibility of the overall ESG dive process across the investment lifecycle.

ESG Dive vs. ESG Screening vs. ESG Integration

The term "ESG dive" is sometimes used interchangeably with other sustainability-related investment practices, but conflating these approaches obscures important distinctions in rigor, purpose, and application. Understanding how an ESG dive differs from ESG screening and ESG integration helps investors select the right tool for their specific strategy and time horizon.

ESG screening is the most basic and longest-standing approach, dating back to early socially responsible investing (SRI) practices. Negative screening excludes entire sectors or companies—tobacco, firearms, thermal coal—based on predefined exclusionary criteria. Positive screening does the opposite, actively selecting companies that meet minimum ESG thresholds or rank favorably relative to sector peers. Screening is typically rules-based, automated, and applied at scale across large portfolios or index-tracking strategies, requiring minimal ongoing analyst judgment once criteria are established.

ESG integration represents a more systematic approach, embedding environmental, social, and governance factors directly into traditional fundamental or quantitative financial analysis. Rather than excluding or including based on binary criteria, integration treats ESG data as one input among many—alongside earnings quality, balance sheet strength, and competitive positioning—when building valuation models or position sizing decisions. This approach has become mainstream among long-only asset managers and is often discussed alongside broader hedge fund strategies explained, since many fundamental and quantitative strategies now incorporate ESG signals as standard practice rather than a separate overlay.

An ESG dive, by contrast, is a deep, standalone investigative process reserved for situations demanding heightened scrutiny—pre-acquisition due diligence, activist campaigns, fund-of-funds manager selection, or flagging a specific controversy. It is far more resource-intensive than screening or integration, often involving document review, management interviews, and third-party verification over weeks or months rather than being embedded continuously into daily analysis.

Each approach suits a different time horizon and strategic intent. Screening fits passive, scalable mandates; integration supports ongoing active management; and an ESG dive is reserved for discrete, high-stakes decisions where depth outweighs speed—often triggered before a major capital commitment or when red flags demand resolution.

Benefits and Limitations of an ESG Dive

Like any rigorous due diligence process, an ESG dive carries clear advantages alongside meaningful trade-offs. Understanding both sides helps investors calibrate how much resource investment is warranted for a given decision.

On the benefit side, a well-executed ESG dive dramatically improves risk identification. Surface-level ratings can miss emerging controversies, pending litigation, or structural governance weaknesses that only become apparent through document review and management interviews. Investors who conduct deeper diligence are better positioned to avoid value-destroying surprises—stranded asset write-downs, labor scandals, or boardroom conflicts—before they materialize into price shocks. This diligence also supports improved long-term returns, as companies with genuinely strong environmental, social, and governance practices tend to exhibit lower cost of capital, fewer regulatory penalties, and more resilient operations across economic cycles. Finally, an ESG dive enhances investor trust and transparency, giving limited partners and institutional allocators confidence that ESG claims are substantiated rather than marketing language layered over conventional strategies.

However, these benefits come with real limitations. The most obvious is that an ESG dive is resource-intensive—requiring specialized analyst time, access to proprietary data subscriptions, and sometimes on-site verification, all of which raise costs and extend timelines compared to screening or integration approaches. Compounding this challenge is inconsistent data quality across regions and sectors. Disclosure standards vary widely by jurisdiction, and emerging market companies often provide far less granular ESG data than their developed-market peers, forcing analysts to rely on estimates or third-party proxies that may not accurately reflect reality.

A deeper structural issue is the subjectivity of materiality judgments. What counts as a material ESG factor for a mining company differs substantially from what matters for a software firm, and without a universally standardized global reporting framework, analysts must exercise judgment that can introduce bias or inconsistency across teams and firms. This lack of standardization is well documented: MIT Sloan research on ESG rating divergence has shown that major rating agencies often disagree significantly when scoring the same company, sometimes producing contradictory conclusions about whether a firm is a leader or laggard in sustainability performance.

This divergence creates a final risk: analysis paralysis or over-reliance on third-party scores. Investors who treat a single ESG rating as definitive—without independent verification—may make decisions based on incomplete or methodologically flawed inputs. The most effective ESG dives triangulate multiple data sources, apply sector-specific context, and maintain healthy skepticism toward any single numerical score, treating ratings as a starting point for investigation rather than a final verdict.

How Hedge Funds and Alternative Investment Vehicles Use ESG Dives

Hedge funds and other alternative investment vehicles have moved well beyond treating ESG as a compliance checkbox, instead embedding ESG dives directly into the research and due diligence workflows that drive capital allocation decisions. Across learn:types-of-hedge-funds, the depth and application of ESG diligence varies significantly depending on strategy, time horizon, and investor base.

Pre-Investment Due Diligence for Activist and Long/Short Strategies

For activist hedge funds, an ESG dive often serves as the foundation for engagement campaigns—uncovering governance weaknesses such as entrenched boards, misaligned executive compensation, or weak shareholder rights that can be targeted for value-unlocking reforms. Long/short equity managers similarly use ESG dives to inform both sides of the book: identifying companies with deteriorating environmental or social risk profiles as short candidates, while favoring long positions in firms demonstrating genuine governance discipline and sustainable operating practices. In both cases, the ESG dive functions as a forward-looking risk and catalyst identification tool rather than a static compliance exercise.

Fund-of-Funds Manager Selection

Within learn:what-is-a-fund-of-funds structures, ESG dives extend beyond individual securities to the manager level. Allocators conducting operational due diligence increasingly require underlying managers to demonstrate robust ESG policies, proxy voting records, and engagement histories before committing capital. This manager-level ESG dive helps fund-of-funds operators avoid reputational contagion and satisfy their own limited partners' sustainability mandates, particularly as institutional LPs demand greater transparency into how capital is deployed throughout multi-manager platforms.

Legal and Structural Considerations

Launching an ESG-focused hedge fund vehicle introduces unique considerations within the broader learn:hedge-fund-structure-legal-framework, including drafting precise ESG investment mandates in offering documents, establishing exclusionary criteria that withstand regulatory scrutiny, and implementing ongoing monitoring systems to prevent greenwashing claims. Funds marketed under SFDR Article 8 or 9 classifications, for example, must maintain documented processes proving that ESG characteristics are genuinely and consistently applied.

Examples of ESG-Driven Strategies

The alternative investment landscape now features diverse ESG-driven approaches, including impact investing vehicles targeting measurable social or environmental outcomes alongside financial returns, shareholder engagement funds that use proxy voting and dialogue to drive corporate change, and thematic funds concentrated in areas like renewable energy, water scarcity, or circular economy innovation. AlphaMaven's platform reflects this growth directly, listing numerous ESG and impact-focused funds among its 806+ fund listings, giving allocators a searchable window into how deeply ESG principles have permeated the alternative investment universe.

Future Trends in ESG Due Diligence

The methodology behind an ESG dive continues to evolve rapidly as technology, regulation, and market structure reshape how investors approach sustainability-linked due diligence. Analysts and allocators who understand these emerging trends will be better positioned to maintain rigorous, efficient, and defensible ESG processes in the years ahead.

Artificial Intelligence and Automation

Natural language processing tools now scan thousands of pages of corporate disclosures, news articles, NGO reports, and social media sentiment in seconds, flagging controversies or emerging risks that would take human analysts weeks to uncover manually. Machine learning models are increasingly used to detect patterns in historical ESG incidents, predict governance failures before they become public scandals, and cross-reference disclosed metrics against satellite imagery, supply chain data, and regulatory filings. While AI cannot fully replace the qualitative judgment required in a rigorous ESG dive, it dramatically accelerates the data collection and preliminary screening stages, freeing analysts to focus on materiality assessment and investment synthesis.

Regulatory Standardization

Fragmented reporting standards have long been a core limitation of ESG analysis, but convergence is accelerating. The International Sustainability Standards Board (ISSB) standards have been adopted or are being incorporated into regulatory frameworks by over 20 jurisdictions as of 2024, signaling a meaningful shift toward globally comparable sustainability disclosures. As ISSB standards gain traction alongside existing frameworks like SASB and TCFD, analysts conducting an ESG dive will increasingly benefit from more consistent, comparable datasets across geographies and sectors, reducing the rating divergence problems that have historically complicated cross-border ESG assessment.

Real-Time Monitoring

Traditional ESG dives have relied on periodic reviews tied to annual reports or quarterly disclosures. Institutional allocators are now demanding continuous, real-time ESG monitoring systems that flag controversies, regulatory violations, or supply chain disruptions as they occur, rather than waiting for the next scheduled review cycle.

Expansion into Private Markets

ESG due diligence is extending well beyond public equities into private equity, venture capital, real assets, and other learn:types-of-hedge-funds structures, where data scarcity and limited disclosure requirements make the ESG dive process both more challenging and more valuable to allocators seeking differentiated insight.

Conclusion: Key Takeaways on ESG Dives

An ESG dive is far more than a label check or a quick glance at a third-party rating. It is a rigorous, multi-step due diligence process that examines environmental exposure, social practices, and governance structures with the same analytical discipline investors apply to financial statements. By combining quantitative benchmarking, materiality assessment, and qualitative judgment, an ESG dive gives allocators the granular insight needed to separate genuine sustainability leadership from superficial compliance.

The importance of this work will only intensify. Regulatory regimes like the EU's SFDR and the SEC's climate disclosure rules are raising the bar for transparency, while institutional investors increasingly demand proof—not promises—that ESG claims hold up under scrutiny. Rating divergence, greenwashing concerns, and the expansion of ESG analysis into private markets all underscore why a deeper, more rigorous approach is becoming standard practice rather than a competitive differentiator.

For allocators seeking to apply these principles in practice, understanding the broader context of learn:what-is-a-hedge-fund structures and learn:hedge-fund-strategies-explained is a natural next step. Explore AlphaMaven's broader library to deepen your due diligence toolkit and identify funds aligned with rigorous ESG standards.