Pest control safety: never mix products, and never DIY a fumigation

Most pest control chemicals used properly are a small, managed risk. The two things that turn them into hospital cases are mixing products and DIY fumigation. Both happen in ordinary homes, both usually start with the sentence "let me make it stronger", and both are completely avoidable. If you take nothing else from this page: one product at a time, ventilate, and never seal yourself or your family in with anything that fumes, burns or smokes.

Never mix, and what "mixing" includes

Mixing does not just mean pouring two bottles into one bucket. It includes spraying insecticide onto a floor that was just cleaned with bleach or acid, using a toilet cleaner in a drain right after pouring bleach down it, or "topping up" one spray with another because the first "was not working".

• Bleach + toilet acid releases chlorine gas. This is the classic Indian bathroom accident, because both bottles live under the same sink.
• Bleach + ammonia cleaners (some glass and floor cleaners) release chloramine.
• Insecticide + insecticide. Two sprays are not twice as effective; some combinations react and all of them double your exposure in a closed room.
• Insecticide + heat. Do not spray near the stove's open flame, a lit lamp or a burning coil. Aerosol sprays are flammable — this causes real fires and flash burns every year.

If a mix happens: leave immediately, take everyone including pets, open windows from outside the room if you can reach them safely, and do not go back to "check the smell". If anyone has breathing difficulty, chest tightness or burning eyes that do not settle in fresh air, go to a hospital and carry the product bottles or photos of the labels.

Never DIY a fumigation

Fumigation means filling a sealed space with a pesticidal gas or smoke. It is the single most dangerous idea in home pest control.

• Phosphine tablets (sold for grain storage, sometimes offered loose in markets) release a gas that kills in a closed room. They belong only in licensed hands, in sealed grain stores, never in a house. There is no safe amount of this in a bedroom or a cupboard.
• Burning coils, camphor heaps or "smoke bombs" in a closed room to "gas out" mosquitoes or bed bugs, with people asleep inside or returning too soon, causes carbon monoxide and pesticide poisoning. Coils are for ventilated rooms, one at a time, away from bedding and curtains.
• Sealing and bombing a room with multiple aerosol foggers builds an explosive vapour; a fridge compressor clicking on has been enough to ignite it.

Legitimate professional fumigation exists — for shipping containers, warehouses and grain stores — with licences, gas meters, warning placards and clearance testing. Nothing about it can be reproduced with a match and a closed door.

Around children and pets

• Store every pesticide in its original container, capped, on a high shelf or locked cupboard — never in a water bottle or food jar. Most child poisonings are a chemical decanted into a familiar bottle.
• Never leave a spray can, bait pack or chalk piece where a child plays. Insecticide chalk looks exactly like school chalk to a three-year-old.
• Rat poison indoors, loose, is not acceptable in a home with children or pets in any circumstances. Locked bait stations outdoors only.
• After any treatment, children and pets return only when surfaces are dry and the house is aired, the youngest last.

What is safe to do yourself

Gel baits and sealed bait stations placed high or deep, ready-to-use sprays used exactly as the label says with windows open, sticky and snap traps, a steam iron on a mattress seam, sealing gaps with mesh and mortar, and the unglamorous work of removing food and water. Read the label every time — the label is the law of that bottle, including the re-entry time and what it must never touch.

When to hand it over

Anything that needs a sealed room, anything on a scale beyond a spot treatment, termites, bed bugs, wasp or bee nests, and rodents in a home with small children — these are jobs where the professional's value is not just the chemical but the training in where it can and cannot go. A cockroach treatment is ₹799 and a full home treatment ₹2,999 on our rate card; nobody's health is a sensible saving against that.