Pest control threat.

The start of summer seems to figure prominently in the life cycle of many household bugs.  It is a time when we are likely to notice signs of a Cockroach infestation, and many lesser bugs start crawling out of the woodwork.   Most people find this repulsive - but handled the wrong way - protection measures can be deadly to more than just the bugs.

Some people have a pest exterminator regularly spray their home with appropriate chemicals and this is the safest way to solve the problem, but it is expensive.   A " Do it yourself " method is promoted in television advertising and on products found on supermarket shelves that seems to offer a low cost answer.

The " Roach bomb " is a can containing pesticide which the householder is instructed to place on the floor of the room to be treated - and activate by pressing the operating button.   The pressure propellant causes the nozzle to emit a fine spray which hopefully penetrates to where the insects - and their eggs - receive a fatal dose.

The problem seems to be that many householders adopt this method too enthusiastically - and use two or three Roach bombs in the same room - on the principle that " more is better " !    The contents of a single can usually allows the volume of the hydro-carbon propellant to mix with the air at a safe level, but when several cans are used simultaneously they combine to reach an explosive level.

In the past month, Sydney has seen two units in apartment blocks blown apart by Roach bomb explosions. Doors and windows have been blown out and bricks and fittings strewn across nearby streets - and the damage bill has run to thousands of dollars.   Fortunately, the residents escaped serious injury.

All it takes is for an electrical fault to provide the point of ignition and this rich combination of hydro-carbon and air can detonate in a massive explosion.  That is sometimes traced to a faulty water heater or stove,  and even the cyclical nature of a refrigerator motor can provide the spark that sets off a disaster.

The user instructions on the can urge users to switch off the electricity supply while these bombs are activated, but it is a well known fact that many people neither read the instructions - or pay them any heed.

Used carefully, they deliver results with safety, but used to excess and they can introduce a munitions grade explosive weapon to the family home.     They need to be treated with the same care we would give to a hand grenade !