PPPE: plant and personal protective equipment
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Plant health · PPE & biosecurity

PPPE: plant and personal protective equipment

Coveralls, hairnets, gloves and shoe covers do two jobs at once: they keep the human safe, and they keep the human's particles, microbes and pests off the crop. People are the number-one contamination source in any clean space. This is the full rundown: how bad we are, the bare minimum, the room-by-room kit, and the procedures that actually work.

Biosecurity & PPE9 diagramsResearch-backed · 15 sources~17 min read
In this guide
01 Two jobs, one suit02 Accuracy, self-review, and grain-of-salt notes03 The words you need04 How bad humans actually are05 The bare minimum, everywhere06 Different rooms, different kit07 Gowning, in the right order08 Hands and gloves09 The scenarios that catch people out10 Who is responsible: HSWA 201511 The whole thing, in one place
Start here

Two jobs, one suit

Jurisdiction
Jurisdiction note: PPE duties and HSWA wording below are NZ-oriented; other jurisdictions differ.

PPE in a grow is not really about you. In most rooms the gear is there to protect the plant from you: from the skin you shed, the spores on your jacket, the mites on your shoes and the viroid on your hands. The same coverall that keeps your clothes clean also keeps your contamination off the crop. That is why we call it PPPE, plant and personal protective equipment.

People are typically the dominant contamination source in any clean space (exact share varies by facility design)[1]. You cannot stop a human shedding. You can only put a barrier around the human and move them through the building in a controlled way. That is the whole game.

Why this pays for itself

One contaminated mother plant or one shared glove can spread Hop Latent Viroid to an entire crop, and under experimental conditions infection of linked cuttings can approach complete cohort infection within weeks of propagation from infected stock[6]. The spread is mechanical, on tools, cuttings and hands, not airborne. Gloves-per-plant and gowning are not box-ticking; they are crop insurance.

Two different reasons to gown

In cultivation, dry and trim, PPE protects the product. In extraction it flips to protecting the worker (solvents, fire), and in the vault it is mostly security. Same word, different purpose, different kit. This paper is about the biosecurity side, with the legal duties that sit under all of it.

How sure is this?

Accuracy, self-review, and grain-of-salt notes

How sure is this paper?

We've gone to great lengths to keep these guides honest. One of the main ways we do that is self-review: we actively look for claims that are subjective, only lightly backed by literature, or based on grower practice rather than a controlled study — and we call those out instead of dressing them up as settled science.

Often there simply is no paper for the decision you're making. In those cases we're drawing on what other growers report and what has worked in our own rooms. That can still be useful — but it is not a lab proof. Do what works for your plants, your room, and your meters. If a table disagrees with your crop, believe the crop and log the difference.

Solid
Well supported by plant science, standards, or broad multi-source consensus
  • People are major contamination vectors; mechanical HpLVd spread on tools/hands is real
  • Hand hygiene log reductions are log-scale (≈90/99/99.9% class under test conditions)
  • Clean→dirty personnel flow; waste dirty→exit
Operational
What many growers and rooms actually run — start here, then tune
  • Gowning order and two-kit models for cultivation vs post-harvest
  • NZ HSWA PPE framing where applicable
Grain of salt
Subjective, thin literature, single studies, or “this works for us” practice
  • Exact '70–90% of cleanroom contamination is people' as a universal constant
  • Phone-vs-toilet-seat rankings as rigorous biosecurity metrics

See something glaringly wrong? Tell us and we'll fix it. Please open a GitHub issue with the paper name and what looks off (include a source if you have one): Report an accuracy issue. Local law, labels, and licences always override any recipe here. Inline notes labelled grain of salt flag the highest-risk over-trust points in the text.

Vocabulary

The words you need

PPE / PPPEPersonal protective equipment. Here, plant and personal: the same gear protects the crop from the person and the person from hazards.
Gowning / de-gowningPutting on (donning) and taking off (doffing) protective clothing in a defined order, across a clean/dirty line, so contamination never crosses.
FomiteAn object that carries and transfers microbes, a phone, a pen, a door handle, a tool. Hands move contamination from fomite to crop.
BioaerosolAirborne particles carrying living things, skin flakes with bacteria, fungal spores, droplets from speech or a toilet flush.
Cross-contaminationMoving contamination from a dirty area or item to a clean one, for example walking from flower back into propagation without re-gowning.
Hierarchy of controlsThe legal order for managing risk: eliminate, substitute, isolate, engineer, administrate, and only then PPE as the last line[15].
PCBUPerson Conducting a Business or Undertaking, the NZ legal term for the duty-holding business (your employer) under the Health and Safety at Work Act[14].
Reasonably practicableThe legal standard for how far you must go: weigh the risk against the effort and cost of controlling it. High-consequence, cheap-to-control risks must be controlled.
Facility two-track gowning flow
Example. Two kits: cultivation gowning and a separate post-harvest gown-in. Flower coveralls do not walk into dry/trim.Educational diagram
The problem

How bad humans actually are

It is worth sitting with the numbers, because they are the entire argument for gowning up.

How much a person contaminates a roompeople are the number-one source, by a wide margin~70-90%of cleanroom contamination is the people in it100k -> 5Mparticles/min: standing still vs moving fast37M + 7Mbacteria + fungi shed to the air, per person, perhour~10 millionskin flakes shed per day, ~10% carry live bacteriaPPE exists because of these numbers: you cannot stop a human shedding, you can only put a barrier around it.
Figure 1. People are the number-one contamination source in a clean space[1]. You shed roughly ten million skin flakes a day, about a tenth carrying live bacteria[2], and an occupied room gains tens of millions of bacteria and millions of fungal spores per person per hour[3].
  • Movement is the multiplier. A gowned person emits about 100,000 particles a minute standing still, a million walking, and up to five million working fast[1]. Slow, calm movement is itself a control.
  • Your phone is a high-touch fomite. Phones carry skin and environmental flora and order of magnitude more bacteria than a public high-touch fomite that contacts faces and hands, and they ride to your face and back to your hands all day[4].
  • Your shoes are a pest and spore taxi. Soles carry live pathogens and fungal spores, and walking re-launches settled organisms into the air[5]. Mites and powdery mildew arrive on clothing and footwear.
  • The toilet throws a plume. A flush lofts aerosols to about 1.5 m within seconds, viable for minutes to hours; a closed lid cuts it sharply[8].
Hands are the main bridge, and hygiene is not a cure

Washing helps but does not sterilise: alcohol rubs often achieve ~2–3 log reductions (~99–99.9%) under test conditions; plain soap and water remove soil and many organisms without sterilising hands[7]. That is why hand hygiene is a frequent loop at every transition, and why gloves and barriers carry the rest.

The floor

The bare minimum, everywhere

Before any room-specific extras, there is a non-negotiable baseline for entering any production or handling area. It mirrors food-GMP personnel rules[9] and WHO good agricultural and collection practice[10].

  1. Clean, dedicated outer garment put on at entry (gown, smock, scrubs or coverall), never your street clothes.
  2. Hair fully restrained, bouffant or hairnet, plus a beard cover for facial hair.
  3. Single-use nitrile gloves, intact, changed when damaged or contaminated.
  4. Controlled footwear, dedicated room shoes or covers, never the boots you wore in from the car park.
  5. Hand hygiene on entry and after any contamination or absence.
  6. No personal items, phone, jewellery, watch, makeup, left in a locker outside.
Strip before you gown

Remove jewellery, watches and makeup and store your phone before you put anything on. They cannot be cleaned, they shed particles, and a ring or watch hides bacteria a glove then traps against the crop.

Hand hygiene log reduction table
Example. Log reduction: 1 log ≈ 90%, 2 log ≈ 99%, 3 log ≈ 99.9%. Mapping 3 log to 83% is wrong.Educational diagram
Room by room

Different rooms, different kit

PPE intensity tracks the value and vulnerability of what is in the room, not a single suit everywhere. Strictest where the genetics live and where product is open and headed to a patient.

PPE escalates by roomstrictest where the genetics live and where product is openVault /storegloves, securityTrim /packhairnet, beardnet, gloves,smockVeg /flowergown, hairnet,gloves, roomshoesDry /curecleanroom gown,product exposedMother /propfull gown, freshgloves per plantTClabsterile gloves,lab coat, ISO-5hoodbar height = PPE intensityextraction is different again: worker-safety PPE (FR clothing, goggles, respirator)
Figure 2. PPE escalates from the vault up to the tissue-culture lab. Mother and propagation rooms get the strictest biosecurity because one infected plant propagates to the whole crop[6].
Order people through the day clean-to-dirty: propagation and mothers first, before anyone has been in flower or post-harvest.
ZonePPE levelKey points
Tissue-culture labAseptic / ISO-5Scrub to elbow, sterile gloves, lab coat, work in a laminar-flow hood, no jewellery
Mother / propagationStrictest biosecurityFull gown, fresh gloves per plant, dedicated tools, serviced first in the day
Dry / cureCleanroom-gradeProduct is exposed and microbial spec is a release gate
Veg / flowerStandard gownGown, hairnet, gloves, dedicated room footwear, sticky mat at the door
Trim / packFood-contact gradeHairnet, beard net, gloves, smock, frequent glove changes
Vault / storeMinimal (security)Gloves to keep product clean; controls are mostly security
Visitors gown to the same standard

A contractor or visitor is the same contamination risk as staff, often worse (they were just somewhere else). Gown them to the room's standard or keep them out of mother, propagation, tissue culture and dry rooms entirely, and log every entry.

The procedure

Gowning, in the right order

Order matters. You gown top-to-bottom so that particles shed while dressing fall onto areas you have not covered yet, and you cross a physical clean/dirty line as you go[13].

Gowning order: top-down, dirtiest off lastparticles fall onto not-yet-covered areas, so cover the top first1Strip: no phone, jewellery, watch, makeup2Hairnet / bouffant + beard cover3Face mask, then eyewear4Inner gloves5Coverall (not touching the floor) + hood6Boot covers, stepping over the line to clean side7Outer gloves over the cuffs8Sanitise hands, enterDe-gown in reverse, dirtiest first: outer gloves, boot covers, coverall rolled inside-out, eyewear, hood, mask by the loops, hairnet, inner gloves, then wash.
Figure 3. Donning order: strip personal items, hair and beard first, then mask and eyewear, inner gloves, coverall and hood, boot covers as you step over the line, outer gloves over the cuffs, sanitise, enter[13].
De-gown in reverse, dirtiest first

Coming out, remove the most contaminated items first and do not touch their outer surfaces: outer gloves, boot covers (stepping back over the line), coverall rolled inside-out, eyewear, hood, mask by its loops, hairnet, inner gloves, then wash. Single-use items go in the right bin in the anteroom.

The procedure

Hands and gloves

Hands are the main transfer bridge, so hand hygiene is the most repeated action in the building. Do it on entry, before clean or aseptic work, after waste or any contamination, after any absence, and again on re-entry[11].

Hand hygiene: the technique and the timingneither soap nor rub sterilises, so it is a frequent loop, not a one-off gate1Wet + soap→2Palm to palm→3Betweenfingers→4Backs offingers→5Thumbs→6Fingertips +nailsSoap + water 40-60s (preferred when soiled) · Alcohol rub 20-30s (≥60% alcohol)When: on entry, before clean/aseptic work, after waste or contamination, after any absence, on re-entry.Alcohol rub removes ~83% (about 3 log); plain washing ~58% (about 2 log). Both leave survivors, so repeat at every transition.
Figure 4. The technique covers every surface (palms, between fingers, backs, thumbs, fingertips and nails). Soap and water for 40 to 60 seconds when hands are soiled; an alcohol rub of at least 60% alcohol for 20 to 30 seconds otherwise[11].
Taking gloves off without touching the dirty sideglove-to-glove, then skin-to-skin1Pinch the outside ofone cuffglove touches glove only→2Peel it offinside-out, hold itin the still-gloved hand→3Bare fingers insidethe other cuffpeel off over the first,bin, washGloves never replace hand hygiene: wash before donning and immediately after removal. Bare skin never touches a glove exterior.
Figure 5. Gloves are the most contaminated item, so they come off first and inside-out, glove-to-glove then skin-to-skin, so bare skin never touches the dirty exterior[12].
Gloves do not replace washing

A glove is a barrier, not a clean hand. Wash before you don and immediately after you doff[12], and change gloves between plants in mother and propagation and any time they touch a non-clean surface. A dirty glove spreads viroid just as well as a dirty hand.

The daily traps

The scenarios that catch people out

Phones and personal items

No phones, earbuds, jewellery, watches or makeup in production or clean areas. A phone is a fomite you hold to your face and cannot clean[4]. Lockers outside the gowning room, everything in before you gown.

The toilet

Toilets must not open into production. A flush throws a viable bioaerosol over a metre in seconds[8], so anyone back from the restroom is a bridge until they have washed and re-gowned.

The toilet is outside the clean envelopea flush plume reaches ~1.5 m in 8 seconds and stays viable for minutesDe-gownbefore the toilet→Use toiletlid down: ~12xless aerosol→Wash handssoap, 40-60s→Wash + sanitiseagain on return→Re-gownfresh garments,re-enterToilets must not open into production. Anyone back from the restroom is a bioaerosol bridge until they have washed and re-gowned.
Figure 6. De-gown before the toilet, close the lid before flushing, wash, then wash and sanitise again on return and re-gown with fresh garments before re-entering[8].

Eating and breaks

No eating, drinking, gum or vaping in production. De-gown to leave for a break area, then wash and re-gown on the way back.

Footwear and the floor

Stopping what walks in on shoesfeet and floors are a top tracking vector for spores and pestsdemarcation lineDIRTY sideCLEAN sideStreet shoeSticky mat~99% @ 0.5umFootbath(quat / H2O2)Dedicated room bootor shoe cover, step overBoot-swap at the line: street shoe off on the dirty side, clean room boot on as you step over. Never carry outside soles onto the clean side.
Figure 7. Layered threshold controls: a sticky mat captures most particles, a footbath disinfects, and a dedicated room boot or shoe cover goes on as you step over the demarcation line[5].

Cross-contamination: one-way flow

One-way flow: dirty to clean, never backpeople, materials and waste move in one direction onlyStreet /lockersGowningairlockCleanproductionFinishedoutdemarcation line: dirty hand never touches clean sidebacktracking = re-gownPositive-pressure, filtered, directional air backs the layout up so dirty air is never pulled toward the canopy.
Figure 8. Move people and clean materials clean → dirty; waste and used PPE only dirty → exit. Never back. Backtracking means re-gowning, and a dirty-side hand or sleeve must never touch the clean side.
The law (NZ)

Who is responsible: HSWA 2015

In New Zealand, PPE and hygiene are not just good practice, they are legal duties under the Health and Safety at Work Act 2015[14], overseen by WorkSafe[15].

PPE is the last line, not the firstNZ law requires higher controls before you rely on PPEEliminateremove the hazardSubstituteswap for saferIsolateseparate people from itEngineerguards, airflow, designAdministrativeSOPs, training, signagePPElast resort, supplements onlymostleasteffective
Figure 9. The law requires you to control risk by the hierarchy of controls and treat PPE as the last line, after eliminating, substituting, isolating, engineering and administrative controls[15].
The business (PCBU) must
  • Ensure worker health and safety so far as is reasonably practicable (s36).
  • Apply higher controls before relying on PPE.
  • Provide PPE and free replacements, and never charge workers for it (s27).
  • Give information, training, supervision and adequate facilities.
Workers must
  • Take reasonable care for their own and others' safety (s45).
  • Follow reasonable instructions, wear the required PPE, follow gowning and hygiene SOPs.
  • Not misuse or interfere with anything provided for safety.
  • Visitors carry the same take-care and follow-instruction duties.
PPE is the last control, not the first

PPE supplements higher controls, it does not replace them[15]. Design the rooms, airflow and flow to remove the hazard first; the gown is what catches what is left. And the business pays for it, charging a worker for required PPE is an offence[14].

Cheat sheet

The whole thing, in one place

Baseline, every roomgown, hairnet + beard net, gloves, room shoes, wash, no personal items
Gown orderhair -> mask -> eyewear -> inner gloves -> coverall -> hood -> boot covers -> outer gloves
De-gownreverse, dirtiest first, then wash
Hand washsoap 40-60s, or alcohol rub 20-30s (>=60%)
Glovesoff first, inside-out; never replace washing; per-plant in propagation
Phonesbanned in clean areas, lockers outside
Toiletde-gown, lid down, wash, wash + sanitise on return, re-gown
Flowclean → dirty for people/materials; dirty → exit for waste, re-gown to backtrack
Law (NZ)PCBU provides PPE free (s27); PPE is the last control
The mindset that makes it stick

Frame every glove and gown as plant protection first. A human cannot help shedding millions of particles an hour. The suit, the order, the flow and the wash are simply how we keep that off a crop that a single contaminated touch can ruin.

Related papers
IPM: pest management
Scout, decide, act
Mould risk
Spot and stop bud rot
Tissue culture
Clean up genetics from a speck of tissue
Daily checks
The self-completing facility round

References

  1. Cleanroom contamination analyses: personnel are typically the dominant contamination source (industry figures often cite a large majority; exact share varies by facility); a gowned worker emits ~100,000 particles/min at rest, ~1,000,000 walking, up to ~5,000,000 in active work. (industry/manufacturer or non-journal source) https://www.precgroup.com/70-percent-of-cleanroom-contamination/
  2. Noble / CDC Emerging Infectious Diseases: humans disseminate ~10^7 skin squames per day, of which roughly 10% carry viable bacteria. https://wwwnc.cdc.gov/eid/article/7/2/70-0225_article
  3. Human microbial-emissions research: an occupied space gains roughly 37 million bacterial and 7 million fungal genome copies per person per hour above the unoccupied baseline. https://pmc.ncbi.nlm.nih.gov/articles/PMC7950481/
  4. Mobile phones as fomites: high-touch devices carry skin and environmental flora (methods and comparisons vary across studies), isolates including S. aureus, E. coli and Candida. https://pmc.ncbi.nlm.nih.gov/articles/PMC3939586/
  5. Shoe-sole and floor contamination: soles carry MRSA, C. difficile, E. coli and other organisms; walking re-disperses settled organisms, contributing a meaningful share of airborne CFU. (industry/manufacturer or non-journal source) https://www.infectioncontroltoday.com/view/shoe-sole-and-floor-contamination-new-consideration-environmental-hygiene
  6. Mechanical transmission and management of Hop Latent Viroid (HLVd) in cannabis: spread via contaminated tools and cuttings; under experimental conditions linked cuttings can approach complete infection within weeks; controls include fresh gloves per plant, tool sterilisation and footbaths. Plants (MDPI) 2025, 14:830. https://www.mdpi.com/2223-7747/14/5/830
  7. Comparative hand-hygiene efficacy: alcohol-based handrubs often achieve ~2–3 log reductions of transient flora under test conditions (~99–99.9%); soap and water remove soil and many organisms but neither sterilises hands. (Note: 1 log ≈ 90%, not ~58–83%.) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC117885/
  8. Toilet-flush bioaerosol ('toilet plume'): a flush lofts aerosols to ~1.5 m within seconds; particles remain viable for minutes to hours, and a closed lid produces markedly less aerosol. https://pmc.ncbi.nlm.nih.gov/articles/PMC9732293/
  9. US FDA. 21 CFR 117.10, Personnel (current good manufacturing practice for food): clean outer garments, personal cleanliness, hand washing, hair restraints, glove integrity. (industry/manufacturer or non-journal source) https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-117/subpart-B
  10. World Health Organization (2003). WHO guidelines on good agricultural and collection practices (GACP) for medicinal plants. (industry/manufacturer or non-journal source) https://www.who.int/publications/i/item/9241546271
  11. World Health Organization. Hand hygiene: the Five Moments and recommended technique (soap-and-water 40-60s; alcohol-based handrub 20-30s, ≥60% alcohol). (industry/manufacturer or non-journal source) https://www.who.int/teams/integrated-health-services/infection-prevention-control/hand-hygiene
  12. US CDC. How to safely remove gloves: glove-to-glove then skin-to-skin, peeling inside-out so bare skin never contacts the contaminated exterior; hand hygiene before and after. (industry/manufacturer or non-journal source) https://www.cdc.gov/ebola/media/pdfs/2024/05/poster-how-to-remove-gloves.pdf
  13. GMP / cleanroom gowning and de-gowning procedures: top-to-bottom donning order across a clean/dirty demarcation bench, reverse dirtiest-first removal. (industry/manufacturer or non-journal source) https://www.pharmanow.live/pharma-manufacturing/cleanroom-gowning-procedures-guide
  14. Health and Safety at Work Act 2015 (NZ): s36 PCBU primary duty of care; s45 worker duties; s27 PCBU must provide what is required (including PPE) and must not charge workers for it. (industry/manufacturer or non-journal source) https://www.legislation.govt.nz/act/public/2015/0070/latest/DLM5976894.html
  15. WorkSafe New Zealand and the Health and Safety at Work (General Risk and Workplace Management) Regulations 2016, reg 6: control risk by the hierarchy of controls, with PPE as the last resort. (industry/manufacturer or non-journal source) https://www.worksafe.govt.nz/managing-health-and-safety/getting-started/introduction-hswa-special-guide/

Citations marked in-text as [n] map to this list. Primary literature and official guidance except where noted. Cannabis tissue culture is strongly genotype-dependent, verify dilutions, hormone doses and local regulations against the primary sources before relying on them.