Health surveillance establishes a health baseline, identifies change over time and supports early clinical referral. It can only detect evidence of harm after biological effects have begun — which is why it supplements exposure control rather than replacing it.
Health surveillance is a planned occupational health programme for workers whose silica exposure presents a credible risk of disease. Its purpose is to establish a health baseline, identify changes over time, support early clinical referral and reveal patterns that may indicate inadequate workplace prevention. It is not a substitute for exposure control: surveillance can only detect evidence of harm or altered function after biological effects have begun.
Inclusion should be based on a documented risk assessment rather than job title alone. Relevant triggers include repeated work with silica-containing materials, uncontrolled or partly controlled high-energy processing, significant historical exposure, abnormal exposure results, failure of engineering controls, or entry into a role where material composition and exposure potential remain uncertain. Contractors, maintenance workers and cleaners may need inclusion where their exposure is comparable with that of production workers.
A baseline assessment is ideally completed before a worker starts silica-exposed work, or when an existing programme is introduced. It creates a reference against which later findings can be compared and helps distinguish pre-existing conditions from subsequent change.
The occupational history should cover previous materials and tasks, duration and intensity of work, use of controls and unusual high-exposure incidents. The medical history should consider respiratory symptoms, previous lung disease, tuberculosis, smoking history, kidney disease and autoimmune conditions. A physical examination may be added according to the occupational physician's judgement. These components are found in recognised international surveillance programmes but should be adapted to the worker, exposure profile and local clinical setting.
Baseline assessment is not a fitness-selection exercise designed to exclude workers with minor abnormalities. Its primary function is prevention and clinical protection. Any decision about work restrictions should be individualised, medically justified and proportionate to the actual risk.
A structured respiratory questionnaire provides a consistent record of symptoms such as cough, sputum, wheeze, breathlessness and exercise limitation. Comparison over time is often more informative than a single answer. Questionnaires should also record changes in work, exposure circumstances, smoking status and respiratory infections.
Spirometry measures forced expiratory volume and forced vital capacity and can identify obstructive, restrictive-suggestive or mixed patterns. Serial spirometry may reveal an abnormal decline even when a single result remains within a population reference range. Reliable interpretation depends on trained staff, acceptable manoeuvres and quality-controlled equipment.
Spirometry has important limitations. It does not diagnose silicosis, does not identify silicotic nodules and may remain normal during early radiographic disease. A reduced forced vital capacity may suggest restriction but cannot confirm it without further lung-volume testing. Abnormal results can also arise from asthma, chronic obstructive pulmonary disease, poor test technique, temporary infection or other conditions. Results should therefore be interpreted clinically rather than used as a stand-alone pass-or-fail test.
Chest imaging is used to look for radiographic changes consistent with pneumoconiosis. A standard postero-anterior chest radiograph remains widely used in occupational programmes because it can be compared systematically over time. Computed tomography is more sensitive for some abnormalities, but it involves greater radiation exposure and is generally reserved for clinical investigation rather than routine first-line surveillance.
The International Labour Organization International Classification of Radiographs of Pneumoconioses provides a standardised method for describing the type, size, profusion and distribution of small opacities, as well as large opacities and other relevant features. It is a classification system, not a diagnosis. Its value is consistency: trained readers can record appearances in a reproducible format, allowing comparison between examinations, readers and worker groups.
Images should be interpreted by physicians competent in pneumoconiosis radiography using appropriate standard images and current technical guidance. An abnormal classification must be considered alongside exposure history, symptoms, examination and other investigations; infection, sarcoidosis and other lung diseases may produce overlapping appearances.
Surveillance frequency should be set by an occupational physician using exposure intensity, duration, age, previous findings and the reliability of workplace controls. A programme may use more frequent review for workers with heavy historical exposure, recurring high-risk tasks or uncertain controls, and less frequent review where exposure is demonstrably low and stable. New symptoms or a significant exposure incident should trigger review outside the normal timetable.
Records should be retained securely for the long term because silica-related disease may appear many years after exposure. The record should preserve exposure history, questionnaires, spirometry traces and interpretations, imaging reports, referrals and work recommendations. Records should remain retrievable when a worker changes role, employer or country, subject to applicable data-protection and medical-record rules.
An abnormal finding should lead to confirmation, not automatic diagnosis. The occupational health professional may repeat a doubtful test, arrange specialist review, request further imaging or lung-function studies, and consider assessment for tuberculosis. Immediate exposure review may be appropriate while clinical clarification is under way.
Detailed medical information belongs within the confidential clinical relationship. Employers generally need a functional opinion: whether the worker is fit for the role, whether temporary or permanent exposure restrictions are recommended, whether specialist assessment is required, and when review is due. Diagnoses, imaging details and unrelated medical history should not be disclosed without the worker's informed consent unless a specific legal exception applies.
Confidentiality does not prevent anonymised or aggregated findings from supporting prevention. A cluster of respiratory symptoms, abnormal declines in spirometry or compatible imaging findings in a work group should prompt examination of tasks, materials and controls. The employer should receive enough non-identifying information to act on the workplace risk without receiving unnecessary personal clinical data.
Health surveillance detects possible harm that has already occurred. Its most important organisational output is therefore feedback into exposure prevention. A programme that repeatedly examines workers but does not investigate adverse trends is not functioning as an effective occupational health system.
A reference point taken before work begins separates pre-existing conditions from later change.
An abnormal decline can show while every individual result still sits within a reference range.
The ILO system records radiographic appearance consistently; it does not diagnose disease.
A cluster of abnormalities in one work group should trigger investigation of tasks and controls.
No UAE-wide legal requirement for silica health surveillance has been identified. In Abu Dhabi, the Occupational Standards and Guideline Values document (2016), Schedule A, lists alpha-quartz and cristobalite at a time-weighted average of 0.025 mg/m³ for the respirable fraction and classifies them A2. Its status needs stating precisely. Section 3.2 of that document says the Schedule A values shall be adopted as maximum allowable limits, while the document's own introductory note describes its standards and guideline values as non-mandatory requirements — and it sits in the Standards and Guideline Values class, not among the Codes of Practice, which the Abu Dhabi Public Health Centre describes as mandatory for all entities. The framework has since been renamed ADOSH-SF under that Centre, which now records the Standards and Guideline Values document as suspended and directs entities to comply with relevant local or federal standards in force. The value is therefore a published reference point, not an enforceable UAE limit. Medical-surveillance criteria used in other countries provide recognised practice but do not constitute UAE legal requirements. Surveillance criteria should not be reduced to a single threshold, because uncertainty, historical exposure and short periods of intense exposure may also be relevant.
Recognised practice, not a UAE legal duty
Not automatically. Inclusion should follow a competent risk assessment that considers the materials, tasks, frequency, control reliability, historical exposure and potential intensity of exposure.
No. Spirometry measures airflow and volume, while imaging examines structural changes. The tests provide different information and neither should be treated as a stand-alone diagnosis.
Normally, the employer should receive a fitness and work-restriction opinion, any need for review or referral, and relevant preventive recommendations. Detailed clinical information remains confidential unless the worker authorises disclosure or law requires it.
No. A normal result means no relevant abnormality was identified at that examination. It does not prove that current exposure is safe or that future disease cannot develop.