Cool air need not be fresh air!

Whenever we go out in a car, I ask my family members to shut all the windows. Even when at home - I stay in a very highly polluted area of the city - I shut all the doors and windows during the peak traffic time. 

But my friends and relatives object to this and say -'The house/car is hot. Open the windows - you will get fresh air!'

"Fresh air? In a highly polluted area when the traffic is reaching its peak and jamming? Forget it. You can actually smell the toxic chemicals around and feel breathless. If you want to protect yourself, close the doors and windows", is what I tell them.

Then again when I think about it, I realize that people think that 'relatively cool' air is fresh air and hot air is bad air! What an illusion?! In a hot country, this feeling is quite expected from laymen.

Several studies show that traffic jams and lots of traffic in an area cause immense pollution of air - hot or cold. And  opening the doors and windows brings it into your vehicle or house, again hot or cold. Moreover switching on fans suck more dirty air from outside to inside.

Heavy traffic and long traffic jams may cause exposure to toxic fumes, and potentially increase various health risks, including cancer, according to experts. Exposure to outdoor air pollution is among the top ten health risks faced by humans and is especially pronounced in urban concentrations, according to the World Health Organization (WHO). In October 2013, WHO classified outdoor air pollution as being carcinogenic to humans. The findings showed that when vehicles stop at red lights, they go through different driving cycles such as idling, acceleration and deceleration and emission of toxic fumes.  If you live in a "major city" then the air pollution you suck into your lungs each day could be shortening your life expectancy even more than the heavy smokers and radiation exposure suffered by survivors of the Chernobyl disaster!

These emissions take more time to disperse, especially in built-up areas and end up accumulating in the air at traffic signals. Thus, the people sitting inside cars, with closed windows but with fans switched on, can be at an increased risk of exposure to the outdoor pollutants, the scientists say.

Switching on the fan sucks the dirty air from outside to inside the vehicle, resulting in an accumulation of pollutants in the car. However, it may be relatively safe to put fans onto the setting where they re-circulate air within the car without drawing polluted air in from outside.

Where possible and with weather conditions allowing, it is one of the best ways to limit your exposure by keeping windows shut, fans turned off and to try and increase the distance between you and the car in front while in traffic jams or stationary at traffic lights. If the fan or heater needs to be on, the best setting would be to have the air re-circulating within the car without drawing in air from outdoors.

So if you are walking outside, avoid, traffic signal areas and main roads, use by-lanes instead. Shut all your car/house windows and doors during heavy traffic hours and open them only when there isn't much traffic or during early hours of the day.

And you have to revisit your thinking that relatively cool air is fresh air and will be pollution-free. 

Cold Air is heavier than Warm Air. Cold air is denser than warm air. The molecules are packed closer together. The amount of water vapour in the air also affects the density of the air. The more water vapor that is in the air, the less dense the air becomes. That is why cold, dry air is much heavier than warm, humid air. 

We all know that in the atmosphere around us when hot and cold air meet, the warm air rises above the cool air, creating a low pressure zone. Warm air tends to cool as it reaches higher elevations, with the liquid in it condensing and forming clouds and rain. Cool air rushes in to fill the low pressure zone, pushing more warm air up and creating a cycle that can result in high winds and storms. 

So when the 'relatively cooler air' outside arrives inside when you open a door or a window, it pushes the warm air inside up,  creating an immediate feeling of coolness and freshness (don't forget that the air in a heavy traffic zone will be very bad) but soon an equilibrium occurs and whatever feeling of freshness you have about it prove to be false.

But when it rains, the situation will be different. The pollutants in the air gets down with the rain water onto the streets, then the cool breeze coming in undoubtedly will be fresh. Yes, you can open your doors and windows then.

In general, winter weather systems promote the mixing of the layers of the atmosphere, diluting pollutants, and sometimes those systems import cleaner air from other parts. But mixing can be inhibited in temperature inversions, which are more common in winter in most places. In an inversion, the temperature increases with altitude, rather than the more typical decrease. The inversion can cause pollutants to build up near the ground.

Need we say winter cold air  causes more irritation in some people  especially those with asthma and nasal allergies, can react to cold air with cold-air-induced rhinitis, characterized by a runny nose and congestion. In some people it can even trigger an asthma attack. And when this cold air is mixed with pollutants? A disaster is waiting to happen in your respiratory track!

No doubt, indoor pollution can actually be harmful too - and this can rapidly rise depending on what activity you are doing at home. It tends to be a different soup of chemical pollutants from the ones we encounter outside and can effect us. Our centrally-heated, carpeted, airtight homes only act to aggravate the situation.

Therefore, keeping your house pollution-free - which situation you can control if you want - while you are closing your doors and windows is very important. How can you do this? Find here: how-indoor-air-can-be-purified-naturally