Workplace Air Quality and Environmental Conditions
This publication was designed as a reference manual for factory inspectors. It considers the nature of air contaminants, methods for their measurement, assessment of the results of these measurements and, in general terms, the nature and design principles of contaminant control. Ventilation is the major means by which this control can be achieved. Other control measures and strategies such as substitution, process enclosure, filtration, and dynamic and wet separation are also considered in some detail.
Contaminant control encompasses not only physical industrial air pollutants such as dusts and smokes (solids); steams and mist (liquids); or vapours and fumes (gases) which may present hazards of toxicity and/or flammability or may simply be offensive, but also those 'pollutants' which may be factors in unsatisfactory environmental conditions. Thus, air temperature, relative humidity, radiant heat, and the rate of air movement are all physical variables which can result in atmospheric conditions which are not the optimum.
Table of Contents
Chapter 1: Introduction
Chapter 2: Legislation Relating to Contaminant Control
2.1 Introduction
2.2 The Factories and Commercial Premises Act
2.3 Regulations
2.3.1 General
2.3.2 Abrasive Blasting Regulations 1958
2.3.3 Asbestos Regulations 1983
2.3.4 Electroplating Regulations 1950
2.3.5 Lead Process Regulations 1950
2.3.6 Spraycoating Regulations 1962
2.3.7 Summary
2.4 The Clean Air Act 1972
Chapter 3: Air Contaminants
3.1 Physioloqical Effects of Airborne Contaminants
3.1.1 The Respiratory System
3.1.2 Chronic and Acute Lung Diseases
3.1.2.1 Introduction
3.1.2.2 Examples of Chronic Occupational Lung Disease
3.1.2.3 Examples of Acute Occupational Lung Disease
3.1.2.4 Sensitisation
3.1.3 Absorption into the Blood
3.1.3.1 Introduction
3.1.3.2 Toxic Effects of Absorbed Contaminants
3.1.4 Summary
3.2 Concentration Limits, Their Measurement, and Departmental Policy
3.2.1 Workplace Exposure Standards
3.2.1.1 General
3.2.1.2 Some Special Points About WESs
3.2.1.3 Categories of WESs
3.2.1.4 Establishment of WESs
3.2.1.5 Skin Notation
3.2.2 Measurement of Concentrations of Airborne Contaminants
3.2.2.1 Measurement Philosophy
3.2.2.2 Methods of Sampling
3.2.3 Departmental Policy Regarding Workplace Exposure Standards
3.2.3.1 Interpretation of Legislation
3.2.3.2 Measurement Policy
3.3 Strategies for Contaminant Control
3.3.1 General
3.3.2 Substitution
3.3.3 Process Modification
3.3.4 Segregation
3.3.5 Process Enclosure
3.3.6 Ventilation
3.3.7 Summary
Chapter 4: Atmospheric Conditions
4.1 General Considerations
4.2 Explanations of Terms
4.3 Thermal Comfort and Bodily Responses
4.3.1 General
4.3.2 Adaptive Responses of the Body
4.3.3 Bodily Acclimatisation
4.4 Comparison of Effective Temperature and Equivalent Temperature as
Indices
4.4.1 General
4.4.2 Disadvantages of Equivalent Temperature
4.4.3 Disadvantages of Effective Temperature
4.4.4 Summary
4.5 Measurement of Physical Parameters
4.5.1 General
4.5.2 Thermal Comfort Meter
4.5.3 Derivation of Equivalent Temperatures
4.6 The Inspector's Role in the Assessment of Adequate Atmospheric
Conditions 46
4.6.1 What is 'Reasonably comfortable'?
4.6.2 Extreme Environmental Conditions
4.7 Remedial Measures
4.7.1 General
4.7.2 Outline of Particular Measures
Chapter 5: General Ventilation
5.1 Introduction
5.2 Methods of General Ventilation
5.2.1 Air Flow
5.2.2 General System Requirements
5.2.3 Infiltration of Outside Air
5.2.4 Natural Ventilation
5.2.5 Mechanical Ventilation
5.2.6 Combined Natural and Mechanical Ventilation
5.3 Distribution of Airflow Within Rooms
5.4 Specific Requirements of a General Ventilation System
5.4.1 Fresh Air Supply
5.4.2 Removal of Heat
5.4.3 Control of Condensation and Humidity
5.4.4 Dilution Ventilation for Process Contaminant Control
5.5 New Zealand Standards Relating to Building Hygiene and Ventilation
Chapter 6: Local Exhaust Ventilation
6.1 Introduction
6.2 Design of Hoods and Inlets
6.2.1 General
6.2.2 Enclosures
6.2.3 Hoods
6.2.4 Capture Velocity
6.2.5 Flow Into an Inlet or Hood
6.3 Duct Design
6.3.1 General
6.3.2 Energy Losses
6.3.3 Construction of Ducts
6.4 Fans
6.4.1 General
6.4.2 Centrifugal Fans
6.4.3 Axial Flow Fans
6.4.4 The Selection of a Fan
6.4.5 Noise Control
6.4.6 Air Movers
6.5 Fire and Explosion Hazards
6.6 Commissioning, Testing and Maintenance
6.6.1 Commissioning
6.6.2 Testing and maintenance
Chapter 7: Air Cleaning Devices
7.1 Introduction
7.2 Factors Determining the Selection of Air Cleaning Devices
7.2.1 Contaminant characteristics
7.2.2 Airstream Characteristics
7.2.3 Filtration Efficiency
7.2.4 Operating Factors
7.3 Dynamic Collectors
7.3.1 General
7.3.2 Cyclones
7.3.3 Irrigated Cyclones
7.3.4 Dynamic Precipitators
7.4 Fabric Dust Collectors
7.4.1 General
7.4.2 The Filter Fabric
7.4.3 Fabric Collector Types
7.4.4 Cleaning Mechanisms
7.5 Wet Collectors
7.5.1 General
7.5.2 Venturi Scrubbers
7.5.3 Self-Induced Spray Wet Collectors
7.6 Electrostatic Precipitators
7.7 Absolute Filters
7.8 Gas, Vapour and Mist Eliminators
7.8.1 General
7.8.2 Absorption
7.8.3 Adsorption
7.8.4 Combustion
7.8.5 Condensation
Bibliography
Appendix 1
