THE SENSIBLE HOME : Indoor Air Can Become Particle Soup


QUESTION: My house is stuffy and my allergies are bad. Even though I have a central air cleaner, should I run a room air cleaner too? What types are best and do they cost much to run?

ANSWER: Many people, not just those with allergies, suffer from “sick home syndrome.” As homes and offices become more efficient and airtight, indoor air becomes a chemical and particle soup. Only about one-tenth of the particles floating in indoor air are large enough to be visible.

It does make sense to use room air cleaners in addition to a central furnace air cleaner. I use a quiet one in my bedroom at night. Most room-size air cleaners use less electricity than a 100-watt light bulb.

Room air cleaners are especially effective for allergies. Whereas a central air cleaner runs only when the furnace is on, a room air cleaner works continuously. This removes particles and odors before they settle.


There are many effective designs of room air cleaners--HEPA (high efficiency particulate air), electronic precipitators, self-charging electrostatic, ionizers and ozone generators. Some super-effective air cleaners use a combination of these designs in one unit.

Each type of air cleaner is particularly effective for specific-size allergen particles, so don’t just buy the cheapest one on sale. Select one with an activated charcoal final filter to remove odors too. Heavier charcoal is more effective.

HEPA and electrostatic precipitators are the most effective overall, especially for small smoke particles. A HEPA (very dense and finely packed filter material) air cleaner is 99% efficient. Pleated media is a less efficient, loosely packed type of HEPA filter and is less expensive.

Electronic precipitators electrically charge allergen particles as they pass through the air cleaner. These charged particles then stick to collector plates with the opposite charge in the air cleaner.

Self-charging electrostatic filters use a material that develops a static charge as air moves through it to trap the particles. They are most effective for larger allergen particles like mold and pollen.

Ionizers produce negative ions that cause particles to drop out of the air. The particles collect on walls and tables so they can be easily vacuumed.

Ozone generators produce very mild ozone concentrations and use little electricity. Ozone (activated oxygen) chemically destroys odors, smoke, bacteria, etc. Write for Update Bulletin No. 933 showing a buyer’s guide of 20 efficient room air-cleaner manufacturers, listing filtration methods, air-flow rates, number of speeds, weights, prices and an allergen size chart. Please mail $2 and a self-addressed, stamped envelope to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.

A Way to Measure Light Bulb Efficiency

Q: I need to buy some light bulbs. The package lists “lumens” for the bulb. What are lumens and how can I relate them to the bulb’s efficiency?

A: Lumens are a measure of the light output of a bulb. A bulb producing 1,500 lumens is twice as bright as one producing 750 lumens. A typical 75-watt incandescent bulb produces about 1,170 lumens of light.

The efficiency of a light bulb is rated in lumens of light per watt of electricity used. Higher wattage bulbs are more efficient. For example, a 150-watt bulb produces 2,880 lumens. Two 75-watt bulbs, using the same amount of electricity as one 150-watt bulb, produce only 2,340 lumens.

Letters and questions to Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.