Where You Live Has An Unexpected Effect On Your Hair

When it comes to hair health, we usually think about the nutrition aspect, the hair care products we use, and possibly any supplements we might be taking to boost hair growth. Rarely, if ever, do we think about where we live. But there is some science that points toward various environmental and biological factors caused by where we live that could be contributing to hair loss. 

For example, if you live in a country or region that enjoys seasons and you've noticed that your hair starts thinning during the hot summer months, this might be due to something called seasonal shedding, per family nurse practitioner certified in family medicine and dermatology Jodi LoGerfo (via Coveteur). "The reason for this phenomenon may go back to evolutionary times, when animals dealt with molting hair due to the sun," explained LoGerfo. 

Hotter weather also means more exposure to UV light, pollution, and the resulting effects on your skin and hair (per The Indian Express).  Speaking of pollution, if you live in a place that's rife with air pollution, you might notice some unexpected effects on your locks. 

Air pollution could lead to hair loss

According to research released in 2019, there might be a link between hair loss and air pollution, more specifically, dust and diesel particulate matter (PM). After exposing human follicle dermal papilla cells (HFDPCs) to these air pollutants, the study's authors assessed protein levels in hair follicles responsible for hair growth (β-catenin). 

As lead author Hyuk Chul Kwon told Allure, "The research found that when the cells on the human scalp were exposed to common air pollutants created from burning fossil fuels, the proteins in the cells that are responsible for hair growth and hair retention were significantly reduced." So if you live in a large city that has a lot of the common air pollutants, it might be having an unexpectedly damaging effect on your hair. Lifestyle changes associated with living in large cities, such as a nutritionally deficient diet, may also contribute toward hair loss, per Dr. Divya Sharma, a trichologist in Bengaluru (via The Economic Times). 

Stress brought on by living a fast-paced lifestyle can also be one of the reasons you could be losing your hair. According to a 2021 study on mice published in Nature, there is a link between chronic stress and hair loss. Interestingly, the researchers found an acceleration of the hair growth phase when the stress hormone was removed (via The Harvard Gazette). 

But if hot weather can make you shed more, where did the notion that "summer makes your hair grow longer" come from? 

Is hot weather really making your hair grow faster?

The idea that cold weather causes you to shed and hot weather makes your hair grow faster is nuanced at best. If you yourself notice that your locks were longer in the summer months, this might be due to a marginal increase in hair growth, shared board-certified dermatologist at Park View Laser Dermatology, Dr. Robyn Gmyrek (via Bustle). "It's possible that the warmth causes an overall increase in blood flow, which increases circulation — which, in turn, increases the amount of nutrients and growth factors delivered to the hair follicle." 

But this claim has been disputed by some experts, who believe that temperature doesn't have a direct effect on hair growth. A trichologist at the Philip Kingsley Clinic in New York City, Elizabeth Cunnane Phillips, told Huffpost that while there might be a slight increase in hair growth in the hotter months, most of what you're seeing is purely in your head. "More highlights and sun oxidation can cause the demarcation between base and scalp to be more apparent than in the winter months," she explained.

At the end of the day, no matter where you live and what the weather in your country is like, it is important to remember that genetics, nutrition, stress, and other lifestyle factors (and even underlying health conditions) play a more important role when it comes to hair health.