“Reasonably Fit for Human Habitation” and Land Contamination: Proof of Health Risk and Causation Cannot Be Inferred from Symptoms Alone

1. Introduction

This Inner House decision concerns multiple tenant actions arising from the Watling Street housing development, built on a former industrial site containing “made ground” with potential contaminants (including asbestos-related materials, metals, VOCs/SVOCs, PAHs, PCBs and related compounds). The tenants sued their landlord, Lanarkshire Housing Association Limited, seeking damages for personal injury said to have been caused by exposure to contaminants, including through household air and garden soil contact.

The claims were framed as breach of the landlord’s statutory obligation to ensure the houses were “reasonably fit for human habitation”, initially under section 113 of the Housing (Scotland) Act 1987 and later under section 27 of the Housing (Scotland) Act 2001. After a combined proof in 11 actions (binding in the remainder), the Lord Ordinary assoilzied the landlord: the tenants failed on breach and causation ([2024] CSOH 56). The tenants reclaimed (appealed) in the principal action.

Key issues

• Breach: did the level/type/distribution of contamination mean the houses were not “reasonably fit for human habitation”?
• Causation: even if contamination existed, did it cause (or materially contribute to) the particular ailments complained of?
• Appellate review: were there appealable errors in the Lord Ordinary’s findings and assessment of factual and expert evidence?

2. Summary of the Judgment

The Inner House refused the reclaiming motion and adhered to the Lord Ordinary’s interlocutors. The court held that none of the 21 grounds of appeal met the stringent threshold for appellate interference with findings in fact and evaluative judgments.

• The tenants could not discharge the burden of proving that contamination rendered the properties not reasonably fit for human habitation.
• The court rejected attempts to treat the tenants’ reported symptoms and experiences as effectively self-proving (a “res ipsa loquitur” style approach).
• The court upheld the Lord Ordinary’s preference for the landlord’s expert evidence on key disputed matters (both environmental risk assessment and toxicology).
• The McGhee v National Coal Board [1973] 1 WLR 1 “material increase in risk” principle did not assist where multiple possible causes existed and the pursuer still had to prove material contribution.

3. Analysis

3.1 Precedents Cited and Their Influence

(a) Fitness for human habitation — the Morgan test

The Lord Ordinary (and the Inner House in affirming him) treated Morgan v Liverpool Corporation [1927] 2 KB 131 as the leading authority on the meaning of “reasonably fit for human habitation” under the relevant statutory scheme’s predecessor. The key formulation was that a house is not fit where, by ordinary user, damage may be caused to the occupier’s life/limb/health.

Practical consequence in this litigation: it was not enough to show the presence of contaminants or exceedance of screening criteria; the tenants required to prove, on the balance of probabilities, that ordinary residential use created a real risk of injury to health meeting the Morgan threshold.

(b) Appellate restraint on findings in fact

The decision strongly reflects modern appellate discipline in relation to fact-finding and evaluative assessment of evidence. The court relied on a line of authorities including Thomas v Thomas 1947 SC (HL) 45, Henderson v Foxworth Investments [2014] UKSC 41, McGraddie v McGraddie 2014 SC (UKSC) 12, and Carlyle v RBS [2015] UKSC 13, as well as Scottish appellate decisions such as McCulloch v Forth Valley Health Board [2021] CSIH 21 and Henderson v Benarty Medical Practice [2023] CSIH 1.

The Inner House framed the tenants’ problem as one of asking the appeal court to “take a different view” of the evidence without identifying a qualifying error: absent a legal error, lack of evidence, ignoring relevant evidence, “plainly wrong” findings, or inadequate reasoning, the appeal could not succeed.

(c) Causation and multiple potential causes

The court endorsed orthodox causation structure: (i) capability/general causation and (ii) specific causation, with reference to Kay's Tutor v Ayrshire and Arran Health Board 1987 SC (HL) 145 and the approach summarised in Clerk & Lindsell on Torts. In multiple-cause contexts it relied on Wilsher v Essex AHA [1988] AC 1074 and Petroleum Co of Trinidad and Tobago Ltd v Ryan [2017] UKPC 30 to emphasise that where there are competing explanations, the pursuer must prove that the defender’s breach caused or materially contributed to the harm.

(d) The limited role of “material increase in risk” — McGhee

The tenants sought to invoke McGhee v National Coal Board [1973] 1 WLR 1. The Inner House explained McGhee as a case where injury was clearly caused by exposure to a single agent (dust), with the defender’s breach increasing exposure and thus materially contributing to the disease—making the “risk vs contribution” distinction “too unreal”.

By contrast, the tenants’ pleaded and proved position involved multiple potential causes for symptoms/ailments (including pre-existing conditions and alternative explanations), so the “material increase in risk” label could not elide the need to prove material contribution in accordance with Wilsher and Petroleum Co of Trinidad and Tobago Ltd v Ryan. The court also referenced the orthodox texts (Charlesworth & Percy on Negligence, Gloag & Henderson) to the same effect.

(e) Gardening rashes and “ordinary use”

The tenants cited Todd v Claperton 2009 SLT 837 and Rendlesham Estates plc v Barr Ltd [2015] 1 WLR 3663 to argue that inability to garden without developing rashes demonstrated unfitness. The Inner House did not dispute that such facts could be relevant to fitness, but upheld the Lord Ordinary’s conclusion that the tenants had not proved (through evidence as a whole, including expert evidence) that the rashes were probably caused by specific contaminants at the site.

3.2 Legal Reasoning

(1) Statutory duty is assessed by the housing statutes, not imported environmental thresholds

A central theme was the distinction between:

• the landlord’s housing-duty question: are the houses “reasonably fit for human habitation” under the Housing (Scotland) Act 1987 and Housing (Scotland) Act 2001 as construed in authority; and
• the regulatory remediation question under Part 2A of the Environmental Protection Act 1990 (and DEFRA guidance categories).

The Inner House accepted the Lord Ordinary’s approach: Part 2A did not determine the housing-duty issue, but the categories could be a useful reference point because the experts used them in modelling and risk communication. The court rejected the tenants’ complaint that “any relevance” was error—particularly since the tenants themselves had led evidence deploying that framework.

(2) Screening exceedances and modelling are not self-proving of “unfitness”

The Lord Ordinary’s reasoning, upheld on appeal, drew a clear distinction between: (i) exceedance of screening levels (which may trigger further assessment), and (ii) proof that the site conditions pose a health risk meeting the Morgan “ordinary user” standard. The tenants’ attempt to bridge the gap via hypotheses about undiscovered “hotspots” failed because the court accepted the Lord Ordinary’s view that there was no proper evidential basis to conclude such hotspots existed (and, in any event, their own “common symptoms” thesis reduced the materiality of the hotspot issue).

(3) The court rejected “res ipsa loquitur” by another name

The Inner House was explicit that the tenants could not satisfy the burden of proof by the tenants’ accounts of symptoms alone, even if credible. The court treated the tenants’ submissions (“no rational conclusion other than contamination caused injury”) as an impermissible attempt to bypass the scientific and medical complexity by inference. In cases involving environmental toxic exposure, capability and attribution generally demand expert underpinning; the court endorsed the Lord Ordinary’s holistic assessment of lay evidence against medical records and expert interpretation.

(4) Deference to the trial judge’s expert-evidence evaluation

On both environmental and toxicological issues, the appeal largely sought to re-run the “battle of experts”. The Inner House noted the Lord Ordinary’s reasons for preferring the landlord’s experts on key disputes (including critique of the tenants’ expert’s reliance on witness statements over medical records). Importantly, the court treated complaints about alleged expert overreach (e.g., on GP note-taking and health anxiety) as not preserved by objection at proof and, in any event, within the clinician’s expertise and properly weighed by the Lord Ordinary.

(5) Cancer risk: low-level risk, no manifestation, and damages

The tenants argued that an elevated risk of cancer from TCE made the homes uninhabitable and that fear/knowledge of risk should sound in damages. The Inner House upheld the Lord Ordinary’s conclusions: the evidence supported only a theoretical risk at a very low level; none of the tenants had developed cancer; and even if breach were established, liability in damages was not made out on the evidence presented. While the judgment does not attempt a general “no recovery for risk” rule across contexts, it affirms that in this statutory-duty/damages claim the pursuers must still prove actionable loss and causation on orthodox principles.

3.3 Impact

(1) High evidential demands in contamination-based habitability claims

The decision consolidates a practical message: where the alleged unfitness arises from subsurface contamination and low-level exposures, tenants must expect the court to require robust, site-specific expert evidence connecting: (i) measured or reliably modelled exposure pathways, (ii) health-relevant dose, (iii) likelihood of injury under ordinary residential use, and (iv) causation (or material contribution) for the specific symptoms claimed.

(2) Part 2A categories: not determinative, but not taboo

Parties in future Scottish habitability litigation should note the court’s willingness to allow regulatory risk frameworks to appear in evidence as contextual tools, while insisting that the legal test remains the housing-statutory one. A strategy that attacks any reference to Part 2A categories as legally irrelevant is unlikely to succeed where such material forms part of the expert methodology.

(3) Narrowing attempted expansion of McGhee

The judgment continues the modern trend of containing McGhee within situations where causal uncertainty arises within a single-agent mechanism and where the breach can realistically be seen as contributing to the outcome, rather than merely existing alongside multiple alternative causes. In environmental exposure claims with heterogeneous symptoms and pre-existing conditions, the court signals that “material increase in risk” arguments will be closely scrutinised and will not readily displace the pursuer’s onus.

4. Complex Concepts Simplified

• “Reasonably fit for human habitation”: a legal standard (not a regulatory label) focused on whether ordinary residential use creates a real risk of injury to health (drawing from Morgan v Liverpool Corporation [1927] 2 KB 131).
• Screening levels / GAC exceedance: exceeding a screening number often means “investigate further”, not “harm is likely” or “the house is unfit”.
• General vs specific causation: proving a substance can cause a type of harm is different from proving it did cause this person’s harm.
• Material contribution vs material increase in risk: in many multi-cause cases, a pursuer must show the breach contributed to the harm, not merely that it could have increased the chance of harm (Wilsher v Essex AHA [1988] AC 1074; Petroleum Co of Trinidad and Tobago Ltd v Ryan [2017] UKPC 30).
• Appellate restraint: an appeal court does not re-try the case; it intervenes only for defined errors (e.g., no evidence, ignoring relevant evidence, “plainly wrong”, or inadequate reasons), per Thomas v Thomas 1947 SC (HL) 45 and successors.

5. Conclusion

[2026] CSIH 21 affirms that statutory habitability claims grounded in land contamination require rigorous proof of (i) health-relevant risk under ordinary residential use and (ii) causation (or material contribution) for the injuries claimed. The Inner House rejected attempts to infer breach and causation from symptom patterns alone, upheld the trial judge’s evaluation of competing expert evidence, and confined the use of McGhee v National Coal Board [1973] 1 WLR 1 to its proper limits in multi-cause contexts.