Winter Fog, Dust & AQI: Keep Shop Doors Open, Pollution Out

Quick answer: In winter, many shops and showrooms in North India keep the front door open for walk-in customers, but fog, road dust and smoky outside air come straight in with them. A closed door is the best barrier, but it costs footfall. Two products reduce how much outside air enters while the doorway stays open: an air curtain (a fan above the door that blows a stream of air downward) and a PVC strip curtain (overlapping clear strips that people walk through). Neither is an air purifier, but both cut the open-door exchange of air between outside and inside.

This guide explains what each option does in winter, where each fits best, what it costs, and how to get the most out of it.

Why winter is harder on open doors

From late October to February, cities across the Indo-Gangetic plain often see poor air quality. On calm, cold days, smoke and dust stay close to the ground, and the Air Quality Index (AQI) published by the Central Pollution Control Board can stay in the "Poor" to "Severe" bands for days at a time. Fog and smog also bring in dampness and dirt that settle on floors, glass and stock.

For a shop owner this shows up in practical ways:

• More dust on shelves, display glass and packed goods, and more cleaning time.
• Staff near the door working in cold, smoky air for the whole day.
• Heaters inside working harder because warm air keeps escaping through the open door.
• Customers less willing to linger in a cold, draughty entrance.

The aim is not to make indoor air "clean" — that needs filtration — but to stop the doorway from acting as a wide-open vent all day.

Option 1: Air curtain above the door

An air curtain is mounted above the doorway and blows a stream of air down across the opening. With the fan running, the door can stay fully open: people walk through freely, and the air stream reduces how much outside air, dust and insects drift in on their own.

Where it works well

• Shops, showrooms, restaurants, clinics and banks where the door must look open and welcoming.
• Entrances with heavy walk-in traffic, where anything hanging in the doorway would slow people down.
• Doors that open onto a busy road and pick up dust from passing vehicles.

Points to know

• It needs power while the door is open. An automatic door sensor can switch it on only when the door opens, which saves electricity on doors that are sometimes closed.
• Coverage depends on the right size: the air curtain should be at least as wide as the door opening. Our guide on how to size an air curtain for your doorway explains the method.
• Strong cross-winds reduce its effect. On very windy or very exposed doors, a physical barrier usually works better.

Price and warranty at Chronovex: air curtains start at ₹12,649 for a 2 ft Standard Series metal-body model, with sizes up to 7 ft in aluminium, metal and SS304 bodies. Warranty: Standard 1 year, Premium 3 years + 1-year service, Advanced 5-year parts + 1-year service. See the full air curtain price list.

Option 2: PVC strip curtain in the doorway

A PVC strip curtain is a set of overlapping transparent strips hung across the door. People push through and the strips fall back into place. The opening stays visible, and the overlap forms a physical barrier against wind, dust and cold air.

Where it works well

• Back doors, stockrooms, godowns, workshops and kitchen entrances.
• Shop doors where a see-through barrier is acceptable and power use should be zero.
• Doors exposed to wind, where an air stream alone struggles.

Points to know

• Customers have to push through the strips, which some retail formats do not want at the main entrance.
• Clear strips stay transparent longer with regular cleaning; see our guide on cleaning and maintaining PVC strip curtains.
• For a softer feel at a customer door, magnetic PVC strip curtains join back together after people pass, so the gap closes neatly.

Price at Chronovex: a plain transparent 2 mm complete set is ₹189 per sq ft, including hanger hardware and GST. A typical 4 ft × 7 ft shop door works out to 34 sq ft, about ₹6,426. The PVC strip curtain price guide covers all grades and thicknesses, and the strip curtain calculator gives the price for your exact door.

Air curtain or PVC strip curtain: which fits your door?

Many businesses use both: an air curtain at the customer entrance and PVC strip curtains at the service and stockroom doors. Our comparison of PVC curtains vs air curtains goes into more detail.

Getting the most out of either option this winter

1. Measure the opening, not the door frame. For an air curtain, match or exceed the clear opening width. For strip curtains, measure width and height of the opening; the set covers a little extra on each side.
2. Fix gaps around the frame. Air comes in through gaps at the sides and top as well. Seal obvious cracks before relying on any door solution.
3. Keep the area just inside the door clean. A doormat and regular mopping near the entrance stop dust that does enter from spreading through the shop.
4. Use an indoor purifier if air quality matters to you. Air curtains and strip curtains reduce how much outside air comes in; they do not filter the air already inside. For clinics, pharmacies or offices where people spend long hours, add a suitable air purifier.
5. Clean strips and air curtain grilles every few weeks in winter. Dust and soot build up faster in the smog season and reduce clarity and airflow.

Common mistakes to avoid

• Buying an air curtain narrower than the door. The uncovered part of the opening lets air straight through.
• Expecting a door solution to "clean" the air. It limits what comes in; it is not a filter.
• Using a strip curtain at a very busy main entrance where walk-in flow matters most. An air curtain usually suits that door better.
• Leaving the air curtain on all night or with the door closed. A door sensor or a simple switch routine avoids wasted power.

Frequently asked questions

Will an air curtain stop smog from entering my shop completely?

No. It reduces the amount of outside air, dust and fog that drifts in through an open doorway, but some air will still enter, especially in wind. If indoor air quality is important, combine it with an indoor air purifier.

Do PVC strip curtains make a shop look closed?

Clear transparent strips keep the inside visible from the road, so the shop still looks open. Some owners prefer an air curtain at the front door for a completely clear entrance and use strip curtains at back and service doors.

Can I use an air curtain and a strip curtain on the same door?

It is possible on service doors that face strong wind or heavy dust, but for most shop entrances one of the two is enough. Tell us the door size and use, and we will suggest one.

Are prices inclusive of GST?

Yes. Prices shown on chronovex.in include GST, and every order comes with a GST invoice.

Need advice for your door? Send the door width and height, a photo of the entrance and your city on WhatsApp to +91 99977 78202. We will suggest an air curtain size or a strip curtain set and share the price.