If the steady build-up of grime, stains and crumbs on the floor is not enough to spur you to a home cleaning spree, then research on the bugs that lurk in house dust might just do the job. Tests on dust gathered from the tops of door frames in more than 1100 US homes revealed rich communities of fungi and bacteria that varied with the sexes of the home’s occupants, and whether cats or dogs lived with them. Scientists embarked on the study to learn more about the microbes in house dust that might exacerbate breathing problems, trigger allergies, or even have health benefits. “Every time we breath in we are inhaling hundreds or thousands of species and we mostly don’t understand which ones are bad for us, and which are beneficial,” said Robert Dunn, an ecologist who took part in the study at North Carolina State University. “We don’t even know what determines why you breathe in different ones in New Jersey and East London.” The researchers asked volunteers on a citizen science project called The Wild Life of Our Homes to collect dust from the tops of door frames on the inside and outside of homes across the US.

They picked the tops of door frames because they are rarely cleaned, and serve as “passive collectors of settled dust in our homes”, according to a report in Proceedings of the Royal Society B. House dust is an unappealing muesli of skin flakes, food crumbs, soil particles, fabric fibres, animal fur, decomposing insects and their faeces. Living in and on the mixture are microbes that vary with climate, geography, local plant and animal populations, and the house occupants themselves. The scientists counted more than 70,000 types of fungi and over 125,000 kinds of bacteria in the course of their investigation, and discovered that they could predict whether households had cats or dogs from the microbes in their dust alone. The same dust microbes hinted at whether homes had more males or females, as men and women can carry different types of bacteria, and shed them at different rates. Two sorts of skin bacteria, Corynebacterium and Dermabacter, were more plentiful in homes with more males.

Levels of Roseburia, a kind of bacteria found in human faeces, were apparently higher too. That might owe something to differences in hygiene practices, the scientists offer.handheld vacuum cleaner india In homes with more women, a type of bacteria called Lactobacillus was often more abundant. bissell vacuum cleaner not workingThe scientists attribute the source of these particular organisms to the “vaginal microbiome”, the ecosystem of microbes that set up home there.bosch vacuum cleaners australia Fungi and bacteria are more diverse inside homes than outside, because the outdoor species are carried in on shoes and clothing, or blow in on the wind, where they mingle with microbes that are typically found indoors.

Indoor dust was more likely to host moulds and fungi that attack wood, but they also had higher levels of fungi found on human skin, such as Candida and Trichosporon. The types of fungi were tied to geographical locations, but not to who lived in the homes. Residences in the Eastern US had relatively high levels of Agaricomycetes, a class of fungi that includes most edible mushrooms. In Western US homes, fungi that grow on decaying leaves and cause common plant diseases were more common. While the fungi found in house dust were closely linked to local environment, it had little impact on the bacterial populations. Inside people’s homes, the bacteria in dust depended on who, or what animals, lived there. DNA analysis found traces of bacteria that lurk on human skin and in the faeces of household insects. Pets had a huge effect on household bacteria. Owning a dog seemed to raise the levels of 56 different types of bacteria, including Porphyromonas and Moraxella. Cats, meanwhile, raised the levels of 24 types, including Prevotella and Sporosarcina, according to the study.

Most of the bacteria linked to cats and dogs are found in their saliva or faeces. “The pet effect on bacterial communities is in part caused by these pets directly shedding these bacterial taxa from their bodies into our home environment,” the scientists write. From the bugs found in house dust alone, they could predict whether a dog lived at the home with 92% accuracy, and a cat with 83% accuracy. The researchers believe the work is a first step towards understanding the factors that lead to different types of microbes living in homes, and in turn, how they affect people’s health. Ultimately, Dunn said, it might be possible to fill homes with microbes that improve human health. Until then, the options are limited. “If you want to change the types of fungi you are exposed to in your home, then it is best to move to a different home, preferably one far away,” the authors write. “If you want to change your bacterial exposures, then you just have to change who you live with in your home.”

One thing you can do to keep your lungs healthy this season is vacuum. Studies have shown that households with carpeting have higher levels of certain chemicals, ranging from hormone-disrupting phthalates to flame retardants that interfere with your thyroid hormones. The best fix is to replace all that carpeting with hardwood flooring, but if that's not in your budget, you can do the next best thing: Get yourself a really good vacuum cleaner—or at least learn how to be a really good vacuum-er. THE DETAILS: Both Consumer Reports and the Good Housekeeping Institute conduct annual vacuum cleaner tests, and what they've found over the years is good news for bargain hunters. Less-expensive brands like Hoover, Kenmore, Bissell, and Eureka usually rate better than fancier brands that come with hefty price tags. In its 2010 tests, Consumer Reports gave props to all those brands for their ability to pick up tough pet hair, good suction when using tools, performance on both carpeted and hard flooring, and reliability (those brands usually required the least number of repairs).

The Good Housekeeping Institute lauded vacuums sold under those brand names for ease of use, and consumer-minded features like not tipping over when you pull on the hose attachment. Miele was the one high-end brand that performed well in both group's tests, and one reason is that brand's effectiveness at preventing dust from spewing out of the vacuum back into your indoor air, says Carolyn Forte, director of household appliances and cleaning products at the Good Housekeeping Research Institute. "The best vacuums trap air and dirt from being emitted from other parts of the vacuum," she says. And although most vacuums do contain filters that prevent dust from the bag or canister from escaping, those filters don't always prevent dust from escaping from other, non-dust-collecting parts of the machine. "Miele provided the best combination of cleaning and performance from an emissions standpoint." If Miele's $600-and-up price tags give you sticker shock, though, that's OK. Nearly all of the low-cost upright and canister vacuums that Consumer Reports tested scored either "excellent" or "very good" on emissions.

Of the brands mentioned above, Hoover's vacuums scored consistently well in that category. WHAT IT MEANS: You don't have to spend a fortune to get a little peace of mind about what’s lingering in your carpets or in the crevices of your sofa. But even if you aren't in the market for a new vacuum cleaner, there are ways to use your existing dust-buster more effectively. If you're in the market for a new machine: • Look for "HEPA" filters. "Unfortunately, when you're buying an appliance, the hardest thing to tell is how it will work at your house, so the best thing to look for is that a vacuum at least has a HEPA filter," says Forte. HEPA stands for "high-efficiency particulate air," and the filters that use the technology trap microscopically small particles that you can't see but that can lodge in your lungs and cause problems. These filters are extremely effective at preventing air from escaping from a vac back into your home. But Consumer Reports has found that some companies can go a little too far, using filters that are so effective they inhibit the suction of the vacuum cleaner.

HEPA filters aren't a complete panacea—Good Housekeeping researchers have found that some non-HEPA filters are just as good as true HEPA filters at preventing spewing. Still, Forte says, "Not all vacuums are created equal, but HEPA filters are a good place to start." • Opt for bags. Sure, those bagless vacuums don't leave you up a creek when you need to clean but realize you don’t have any bags, however, Forte says they add an extra layer of protection between your lungs and all that vacuumed-up dust. Plus, she adds, "the vacuums that have the bags are usually the best-performing." She says it's particularly key for people with allergies to get bagged vacuums, so they don't wind up inhaling a big cloud of allergens as they try to empty a canister. • Favor the basics over bells and whistles. Nowadays, vacuums have as many features and add-ons as your smartphone. Some come with dirt indicator lights that tell you when your carpets are clean, while others have headlights and automatic height-adjustment features.

But Forte notes that the model's attachments could be all the "technology" you really need. "We're all about making cleaning fast and easy," she says, "and your vacuum cleaner is actually a really great tool for speed-cleaning." Look for dusting attachments you can use on things like lampshades, crevice tools for tight corners and for the crumbs in the corner of your sofa, and wall brushes that clean hard-to-reach corners. Don't be dazzled by a vacuum that doesn't clean anything but carpets. Some of the most expensive models tested by both Consumer Reports and Good Housekeeping didn't come with any attachments at all. Also consider where you'll mostly be using it: Uprights work better on carpeting, while canisters are easier to use if you have stairs. If you just need some extra carpet-cleaning tips:"The more often you vacuum, the less dust and dander you're going to stir up," Forte says. The general rule of thumb is to vacuum once every three to four days, but if that seems undoable, devote 10 to 15 minutes every day just vacuuming one room.

Most vacuum pros recommend swiping the same spot seven times to ensure it gets thoroughly vacuumed. But "who has time for that?" asks Forte. Making sure you overlap your vacuum swipes will get that deep-down dirt without turning your vacuuming into a marathon. • Buy high-efficiency bags. "If you have a bagged vacuum, even going out and buying high-filtration bags, instead of buying the cheapest bags you can find, will trap more allergens," she says. You can buy high-quality vacuum bags from the manufacturer of your vacuum, and online retailers that specialize in allergy-control products carry third-party products that claim to be very efficient in cutting down on dust. • Dump with care. If you have a bagless vacuum, there are a few techniques you can use to prevent dust from winding back up in your home. The first, Forte says, is simply emptying the dust canister outside (back to the wind!). If that's not possible, she recommends wrapping a plastic bag around both your hand and the dust canister, then pulling the canister release.