First aid law never says how many first aiders you need. The code's ratios start at one in 50 and tighten to one in 10.

Regulation 42: a duty in three limbs and four factors

The first aid duty sits in Part 3.2 of the model WHS Regulations, two regulations before the emergency plan. A PCBU must ensure "the provision of first aid equipment for the workplace", that "each worker at the workplace has access to the equipment", and "access to facilities for the administration of first aid"; separately, it must ensure "an adequate number of workers are trained to administer first aid at the workplace" or that workers have access to an adequate number of other trained people. Each limb carries its own penalty. The regulation then names the matters that scale the duty: the nature of the work, the nature of the hazards, the size and location of the workplace, and "the number and composition of the workers and other persons at the workplace". That last phrase does real work: students, clients under care and members of the public count in the assessment, not just employees. Safe Work Australia's first aid duties page adds the temporal edge: access must exist at all times workers are working, and the page spells out that this includes night shifts, overtime and work outside the usual workplace.

High risk or low risk: the assessment that sets everything else

The code's whole apparatus keys off one classification. A low risk workplace is one where injuries needing first aid are likely to be minor, "offices, shops and libraries" in the code's examples. A high risk workplace is one where workers are exposed to hazards that could produce serious injury or illness: the code lists hazardous machinery including mobile plant, chainsaws and lathes, hazardous substances from laboratories to petrol stations, work at heights, confined spaces, welding, demolition, electrical work, exposure to physical violence such as working alone at night or handling cash, and work in extreme heat or cold. The assessment itself follows the standard four steps: identify the hazards that could cause injury or illness, assess their type, severity and likelihood, provide the matching equipment, facilities and training, and review. Injury records, near-miss reports and the safety data sheets of chemicals on site all feed it, and the consultation duties apply: workers must be consulted on the number, location and contents of kits, the facilities, the procedures and the number of first aiders. In a shared workplace the section 46 duty to consult other duty holders lets businesses pool arrangements, a labour-hire host and agency must sort out between them what the placed workers can access, and a small tenant may lawfully rely on a neighbour's first aiders if consultation, cooperation and coordination make the access real.

The kit: one minimum, then the risk assessment decides

Every worker must be able to access a first aid kit, which the code translates as at least one kit per workplace, equipped for the basics it lists: cuts, sprains, minor burns, amputations and major bleeding, broken bones, eye injuries and shock. Beyond that floor the contents follow the risk assessment, more eye pads where chemicals splash or particles fly, burn modules near hot work, extra equipment for remote sites. The kit itself should be identifiable by "a white cross on green background prominently displayed", carry a contents list, and be kept somewhere prominent and quickly reachable, close to the high-risk areas; in a multistorey workplace the code recommends a kit at least on every second floor. Mobile workers whose vehicle is their workplace, couriers, sales representatives, inspectors, should carry a portable kit secured so it cannot become a projectile in a crash. Maintenance is assigned, not assumed: a nominated person, usually a first aider, restocks after use, checks the kit at least every 12 months against a signed and dated inventory, and retires expired or unsealed items.

First aiders: the ratios, the training and the annual CPR refresher

The regulation's "adequate number" becomes concrete in section 3.5 of the code: one first aider for every 50 workers in low risk workplaces, one for every 25 in high risk workplaces, and one for every 10 in remote high risk workplaces, refined by a five-step check that starts from the maximum headcount on site at one time and works through risk, remoteness, mobile and solitary work, and surge factors like shift work, seasonal peaks and first aiders on leave. The minimum training is a nationally recognised statement of attainment from a registered training organisation for the Provide First Aid unit of competency or an equivalent course, the same RTO machinery that runs the licences on the training page. Currency has two clocks: CPR refreshed annually, the first aid qualification renewed every three years. The code also asks for more than the base unit where the risks demand it, remote work, dangerous substances like cyanide, children on site, identified psychological risks, or workers with known conditions such as asthma, diabetes or severe allergies, and for first aiders who move around a site to be findable, a marked vest or a displayed contact number.

Where the duty scales up: rooms, health centres, defibrillators

Facilities scale with the same logic. A dedicated first aid room is recommended for low risk workplaces from 200 workers and high risk workplaces from 100; the code specifies it down to the furniture, an examination couch, a sharps container, a minimum one metre door width for stretcher access, around 14 square metres of floor area, and a trained first aider allocated to maintain it. Very large or very hazardous sites, the code's example is a large mine, may warrant a health centre staffed by a registered health practitioner or paramedic. An automated external defibrillator is not mandated but the code directs a PCBU to consider one where there is an electrocution risk, where an ambulance would be delayed, or where large numbers of the public are present. Emergency eye wash is expected wherever chemicals or infectious material could reach eyes, and emergency showers where serious burns are foreseeable, with the code scaling the hardware honestly: a fixed deluge for the plant, and for a small shop where burns are still foreseeable, a shower hose that attaches to a tap. Its own example is a fish and chip shop.

Procedures, and the seam with the emergency plan

The code expects first aid to be written down: who the first aiders are and which areas and shifts they cover, where the kits and facilities live, who checks them and how often, how workers raise the alarm, and how information about a worker's medical conditions is collected at induction and kept confidential, disclosed to first aiders only with the worker's consent. Two boundary rules are explicit: first aiders should be instructed "not to exceed their training and expertise", and supervisors instructed not to direct them to. First aid records of treatment given feed reviews, and the review triggers are practical, changed work, a new hazard, an incident, or a scheduled mock first aid emergency to prove the procedures work. All of it plugs into regulation 43: the emergency plan must provide for "medical treatment and assistance", and the code notes first aid procedures may be incorporated into emergency planning, the all-hazards duty covered on the emergency preparedness page. The two regulations are neighbours because they answer the same question at different scales: what happens in the minutes after something goes wrong.