The 2009/10 season will be a watershed in the use of crash helmets by recreational skiers. Two decades ago it was unusual to see anyone but a racer wearing a helmet; now, figures from the National Ski Areas Association (NSAA) suggest that in the US most recreational skiers will be doing so this season. Its survey last season found 48 per cent of skiers and boarders were wearing helmets, up by 5 per cent in a year. How can one be so sure of a further increase in helmet usage next season? Because of the death in March of the actress Natasha Richardson after a fall on the slopes of Tremblant, in the Canadian province of Quebec.

Richardson reportedly fell on soft snow on a beginners' slope. She was not wearing a helmet, and she hit her head on the ground. In the immediate aftermath of the fall she seemed hardly injured; but her condition deteriorated swiftly, and the following day she died – as a result, said the New York City examiner's office, of a "blunt impact to the head".

It was her celebrity that made Richardson's death an international event. But it had a particular resonance for skiers. The actress was not engaged in what might be regarded as "dangerous" skiing; on the contrary, to wear a helmet for what she was doing might then have been regarded as overdressing. But since her death it appears that a helmet is a proper precaution for entry-level skiers as well as those who expose themselves to greater risk by skiing harder and faster. In short, everyone who participates in snowsports should wear one.

The view that helmets are primarily for those who venture into hazardous terrain is reflected in their usage, at least in the United States. The NSAA says that 26 per cent of beginners wear them, 38 per cent of intermediates, and 55 per cent of experts. With the potential of the beginners' market about to be tapped, ski-helmet suppliers can expect a good 2009/10 season, especially now that they and their retail outlets are prepared: immediately after Richardson's death, supply could not keep up with demand.

The ski-helmet business also got early notice of another source of demand for its products. After a high-profile accident such as Richardson's, it befits big ski-resort operators to respond, especially in a litigious culture such as America's: to make a show of taking their duty of care seriously could be important in making a defence, should litigation arise over a subsequent injury or death. So in mid-April the Wall-Street-quoted Vail Resorts company, which operates ski areas in Colorado and on the California/Nevada border, announced that from this season all employees would have to wear helmets when skiing or boarding. It also required the use of helmets by all children taking ski and board lessons, and specified that ski-equipment packages for those aged 12 or under must include a helmet – unless a parent or legal guardian signed a waiver.

In October, the other big North American ski-resort operator, Intrawest, followed suit. It announced policies similar to those of Vail Resorts; but in addition it withdrew the right of a parent or guardian to opt out of the children's helmet requirement. It also specifically recommended that all skiers and boarders at its resorts should wear helmets. Intrawest went the extra mile for good reason: as the owner of the Tremblant area at which Natasha Richardson fell, it is in a particularly exposed position.

A cynic might regard the clamour for crash helmets as bordering on the hysterical, for two reasons. First, skiing and boarding are not unduly dangerous: by the NSAA's reckoning, swimming is much more risky. The number of people killed annually in the US while participating in snowsports has been quite consistent since the early 1990s. Excluding those caught in avalanches, the average is 39 fatalities per season. The number of US skier-visits per season, however, reaches into eight figures: last year's total was 57.4 million. The chances of being killed on the slopes are not the proverbial one in a million, but considerably lower than that.

Second, and more troublingly, the numbers do not suggest that helmet-wearing makes winter sports safer. If a rapidly growing number of skiers in the US are choosing to wear helmets on the slopes, one would reasonably expect the fatality rate in the country to have declined. But it has not done so. And eight of those who died in ski accidents in 2008/9 were wearing helmets.

Trawl the internet for research on the use of helmets by skiers and boarders, and you will be amazed how much work is being done. But the material is remarkably diffuse, and rarely decisive. In general, research does favour the use of helmets; but a Norwegian medical team's 2006 report on "Helmet use and the risk of head injuries in Alpine skiers and snowboarders" is fairly representative in the tenor of its conclusion. It judged that "helmet use is associated with the reduced risk of head injuries".

Unfortunately there are many variables to distract the researchers. Much inconclusive stuff has been written about whether it is primarily risk-takers who wear helmets or precaution-takers; another issue which has been floated – and still drifts with the tides – is the possibility that it is the fashion for doing jumps and tricks on both boards and skis which has undone the good work of the growing band of helmet-wearers. Of more concern is the frequently raised suspicion that while helmets can prevent the type of injuries associated with low-speed accidents, they are simply not strong enough to withstand the sort of impact that causes serious head injuries, which are the dominant cause of snowsport fatalities.

When I started wearing a helmet, about a decade ago, it was merely out of interest in a new facet of skiing. Most people of my age who wore them, it turned out, had been forced into it by their children: cocky kids who resisted parental pressure – "If helmets are so important, why don't you wear one?" – gave them no choice. But I just slipped into the habit of wearing mine; with a thin, base-layer "hoodie" worn underneath, it kept out the fiercest January cold; and if energetic climbing in springtime did sometimes send sweat coursing down my spectacle lenses, the heat generated was nothing like that suffered by cyclists in helmets. So on the basis that it might one day save my life, and was unlikely to do me any harm, I have worn the helmet without fail for 10 years. In that time, it has only once hit the ground (not counting the occasions on which I have dropped it). But I am quite a cautious skier.

If the proliferation of helmets hasn't yet impacted on fatality statistics in the US, it has certainly boosted the market: the variety of helmets has expanded, and the volume of sales has increased the incentive to innovate. For this season Salomon (01276 404860; has a new model range called Custom Air based on technology developed by a French protective clothing company, Docmeter. Getting the right fit for a helmet, so that it is firmly seated on the head, can be problematic. Custom Air gets around that by having inflatable pockets in the helmet lining: the wearer simply pumps them up when the helmet is on. It's a cunning piece of kit, available on helmets costing from £100.