Dust mites are microscopic creatures that feed on dead skin cells shed by humans and animals. They are present in most homes and can trigger allergic reactions in some people. This has led many to wonder if cold air can get rid of dust mites.
What are dust mites?
Dust mites belong to the arachnid family and are related to spiders and ticks. There are several different species, but the two most common ones are Dermatophagoides farinae and Dermatophagoides pteronyssinus. Dust mites are only about 0.2-0.3 mm long, making them invisible to the naked eye.
Dust mites feed on dead skin cells shed by humans and pets. An adult person sheds about 1.5g of skin cells per day. These skin cells provide the main food source for dust mites. Dust mites do not drink water, but absorb moisture from the air to survive.
Dust mites thrive in warm, humid environments. They prefer temperatures around 25°C (77°F) and humidity levels above 50%. These conditions allow them to remain active, reproduce rapidly, and have a sufficient food supply.
Why are dust mites a problem?
Although dust mites do not bite humans, they can trigger allergic reactions in some people. Dust mites produce particles of waste and decaying bodies which can become airborne. When inhaled, these particles can cause symptoms like:
- Sneezing
- Runny nose
- Watery eyes
- Wheezing
- Difficulty breathing
Reactions to dust mites are a common trigger for asthma symptoms in children. Dust mites are also one of the most common indoor allergens. Estimates indicate dust mites are a major cause of year-round allergic rhinitis in up to 84% of patients who are allergic to household dust.
Do dust mites die in cold temperatures?
Yes, dust mites are vulnerable to cold temperatures. Prolonged exposure to temperatures below 10°C (50°F) can kill dust mites. However, the exact temperature and duration needed can vary between species.
One study looked at the effects of freezing temperatures on dust mites. It found that after 24 hours at -4°C (25°F), over 99% of dust mites were dead. Lower temperatures killed mites faster. At -15°C (5°F), almost all dust mites died within 4 hours.
Another study looked at the effects of slightly warmer temperatures. After 24 hours at 0°C (32°F), about 95% of dust mites were killed. It took 7 days at 0°C to kill 99% of mites.
Based on these studies, temperatures below freezing are very effective at killing dust mites relatively quickly. Warmer temperatures can also kill dust mites if exposure is prolonged.
Does cold outdoor air reduce dust mites indoors?
Outdoor cold air alone does not significantly reduce dust mites indoors. This is because most homes are heated in winter, allowing dust mites to survive.
One study examined dust mite populations in mattresses during winter and summer. In winter, the outdoor temperature dropped below -15°C (5°F) on some days. Yet the number of dust mites on mattresses remained high, with no significant seasonal variations.
Another study found similar results. Homes in a cold winter climate maintained indoor temperatures around 21°C (70°F). At this temperature, dust mite populations persisted at normal levels.
These studies indicate that cold outdoor air itself does not reduce dust mites inside the home. Even on very cold days, indoor heating allows dust mites to thrive.
Does running the air conditioner kill dust mites?
Using air conditioning can help kill dust mites during hot, humid summer weather. Air conditioners dehumidify the air by condensing water vapor. They also cool rooms well below the optimal temperature for dust mites.
One study found that running air conditioning reduced humidity levels to 45-55% and temperatures to around 22-25°C (72-77°F). At these conditions, dust mite populations declined by over 90% after 2 months.
Another study examined using air conditioning during summer nights. Keeping bedrooms below 24°C (75°F) and 55% humidity at night reduced dust mites by 78% after 3 months.
So while cold outdoor air itself may not impact indoor dust mites, air conditioning units can effectively control mite populations by cooling and dehumidifying indoor environments.
Tips for using cold air against dust mites
To maximize the benefits of cold air against dust mites:
- Run air conditioning units during hot summer weather to cool rooms and reduce humidity.
- Make sure air conditioning is dehumidifying effectively. Aim for humidity levels below 55%.
- Focus on cooling bedrooms at night, as 8 hours of cold exposure is needed to kill mites.
- Wash bedding frequently in hot water to eliminate live mites and allergens.
- Use allergen-proof mattress and pillow covers to isolate mites.
- Limit indoor humidity levels in winter by ventilating rooms and using dehumidifiers.
Alternative methods to reduce dust mites
In addition to cold air, there are other effective ways to control dust mites:
- Wash fabrics at 60°C (140°F) – High temperature washing kills mites and removes allergens.
- Vacuum regularly – Use vacuums with HEPA filters to remove allergens from floors and upholstery.
- Replace fabric furnishings – Items like carpets, curtains and stuffed toys harbor mites.
- Use acaricides – Special chemical sprays kill mites. But effects are short-lived.
- Apply diatomaceous earth – The microscopic particles in this powder kill mites through abrasion and dehydration.
Conclusion
Cold temperatures can kill dust mites, but cold outdoor air alone does not significantly reduce mite populations indoors. Running air conditioning provides cooler, drier conditions that can decrease mites during summer. To most effectively control dust mites, a combination of methods should be used like air conditioning, proper cleaning and laundry practices, and chemical or physical treatments.